trans problems related to maf help please

Hey guys, Need some help asap. I soon will have a Nelson tune, not having one has caused me grief.
as soon has Allen gets back to me ill get a tune.
in the mean time, I have some performance related issues that i got fed up with and wanted to correct. I spoke with the man who did my mail order tune about them. He sugested that I disconect the MAF senser and see if the problems whent away. I did this and drove the truck. 1000% pecent improvement. I reported the results and was waiting for an explanation and some remedey. He asked me if "my trans was shifting ok?" yes it was. Under his advise I just left it un pluged. This truck shifted fine for a day. Then acted like it had a mind of its own, But only retarded.

I still dont know what the problem was/is that should be addressed.

Ok... so I pluged the senser back in, no change, ...disconnect battery no change, ...checked fuses all ok, ....disconnect poss cable only no change ....dissconnect neg only no change.

The truck will only shift if I let off of the gas momentarily. goes thru the gears like that. But At 60 mph high way merge, throttle down trans down shifts and pegs the rev limmiter. From a stop normal throttle acts like full throttle and pegs the rev limmiter. ( goes like hell better that ever) but no shift. Up a hill... additional gas, down shifts bust the tires loose pegs the rev limiter, and Its like right know. not enough time to get your foot of the gas. That truck revs quick and will most likely blow it self up and get me a reckless op traffic ticket or display of acceleration suspension .

What happened to my truck? What was wrong or out of tune with it in the first place?

bump :eek::burnout:

I just reread this full article is at the link below.


The Electronic Pressure Control (EPC) solenoid dictates shift characteristics by changing line pressure. The EPC receives orders from the VCM, which is continuously comparing sensor inputs against its stored algorithms and tables.In theory, this marriage of computer and transmission should provide the perfect line pressure for any situation; FLT has found in practice this is not always the case. The sophistication of the system is its Achilles' heel. An improperly oiled air filter is capable of bringing this system to its knees by oiling down the MAF wires and providing the wrong signal to the VCM, which can result in complete transmission failure. While FLT's approach may seem a step backwards, it removes several potential failure points and replaces them with the proven and dead-simple operation and reliability of a vacuum modulator. This is not to say the EPC solenoid should never be used; it will depend on your application.

Installing A Blown Chevrolet Transmission - GM High Tech Performance Magazine

OOOOH wonderfull
But what happened,??
is it blown up??
or the computer not communicating with the trans,??
did it throw it into some kind of limp home mode.??
WTF i dont get it.
Did I possibly have the wrong maf tabels from day one??
Why would un-plugging the the maf let it run like a raped ape?
( like it should have) started better, idled better, lots more power
I put up with it running kinda ok for over a year, I just reached a point where it was time to get it running like it should and now I got an a$$ ache

BTW its an 2004 5.3l 4l60-e
some mods. comp cams 212 218 563 lift shortie headers
port n polished dbw t body
valve springs udrive pullies trans go shift kit and tci 2400 stall

Casey 23 or sprayed 99 might be able to give you a better idea. They are most likely working on transmissions right now.
This might not be your problem or it could be something really simple.
Don't listen to any thing I say I don't know anything about mechanican. I only know how to mash the gas all the way down. :duh::whack:

simple solutions needed
just removed and cleaned the maf senser, good dousing with contact cleaner looked good before just as clean now. no change.
is there a relearn procedure that i can do, a forced reset ?
can i test the maf with ohm meter?? how and whats goog readings?
how about the signals to and from the maf senser?
simple solutions are the best, any are welcome, I have my nephews this weekend and my truck is broke. I'm afraid to drive it, you know get stuck kids bugging me to go, Pontiac nationals this weekend, 5 year old want his baseball trouphy from the city homedays. oohh this is :help: not good.

Quote:

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Originally Posted by kst3v3n

simple solutions needed
just removed and cleaned the maf senser, good dousing with contact cleaner looked good before just as clean now. no change.
is there a relearn procedure that i can do, a forced reset ?
can i test the maf with ohm meter?? how and whats goog readings?
how about the signals to and from the maf senser?
simple solutions are the best, any are welcome, I have my nephews this weekend and my truck is broke. I'm afraid to drive it, you know get stuck kids bugging me to go, Pontiac nationals this weekend, 5 year old want his baseball trouphy from the city homedays. oohh this is :help: not good.

---

Use an electric type spray cleaner and clean the MAF with it. The little sensors need to be clean free to work. As hot as it is outside, it should evaporate quick. Also your TPS or throttle position sensor has a lot to do on how your trans shifts. I had one go bad and it would slam into gear periodically and shift real hard. RED may be able to give you some insight on the problem. Undo the positive cable for like 20 mins and do a re-learn. Clean the MAF first with Electrical spray they have it at NAPA or just about any auto parts store.

Hope this helps,
Jamest

MAF has a direct effect on shifting. your shifting problem is light throttle
or just WOT throttle?
check to verify the wiring to the MAF is not damaged.. did you get a MIL
when it was unplugged? or have you always had a MIL on?
DTC 101-102-103 are MAF codes plus you should have had some IAT DTC.
the MAF also contains the IAT (intake air temperature sensor) unplugged
the computer thinks its -40° intake air... fuels and timing accordingly
seeing as your disconnected the cables (incorrectly) you now probably
need a transmission relearn as well as a full system relearn.
try this procedure...
disconnect the negative cable (only) lead from battery
disconnect any and all cell phones from the cig lighter jacks
press the horn and brake pedal for one-minute or longer.
reconnect the negative battery lead to battery.
youll need appox 200mi to relearn all the adaptive learning sequences

airdeano

You guys are on the right track ... something is wrong... anytime you talk mail order tune with shift kits and stalls ... it can get EVIL ... I have a 99 vette that goes wide open EPC anything past 50% throttle... it will not release or reset till you turn the key off.... Its in the tune !!

Quote:

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Originally Posted by airdeano

MAF has a direct effect on shifting. your shifting problem is light throttle
or just WOT throttle?
check to verify the wiring to the MAF is not damaged.. did you get a MIL
when it was unplugged? or have you always had a MIL on?
DTC 101-102-103 are MAF codes plus you should have had some IAT DTC.
the MAF also contains the IAT (intake air temperature sensor) unplugged
the computer thinks its -40° intake air... fuels and timing accordingly
seeing as your disconnected the cables (incorrectly) you now probably
need a transmission relearn as well as a full system relearn.
try this procedure...
disconnect the negative cable (only) lead from battery
disconnect any and all cell phones from the cig lighter jacks
press the horn and brake pedal for one-minute or longer.
reconnect the negative battery lead to battery.
youll need appox 200mi to relearn all the adaptive learning sequences

airdeano

---

This is good info, My truck always ran better when it was warming up. So now I see why I was told to disconnect the maf. :nono: fool it into thinking it was cold only its humid 100. Thats a few pieces of the puzzel.
I got no MIL or codes at that time nor have i since. I did get a chance to speek with Allen ( what a great dude ! ) and there is no way of knowing what was turned off in that tune so Mil or Mil means nothing without knowing.
Shifting problem is at any throttle I must back off the gas the for the trans to upshift. but 30% throttle(guess) at any speed down shifts trany to first and reves the motor like your foot is in the radiator. BAMM that fast bounce of the rev limiter. That's scary since the rear wheels are connected to the phsyco drive train.

I cleaned the Maf yesterday no change the Poss cable off all night- not been out to check yet, but from what this post says, That is incorrect so I haven't been in a hurry to find out it didn't work,

The relearn proceedures (that take 200 mins) is there a link or site that I can go to to study them, then I can learn all the adaptive learning sequences. I did a search but not to much luck, Lots of info On CASE learn but i dont know if that is just v-6??

My truck is a conversion trans plant so if the horn and brake have some thing to do with BCM and other electronic wizardry I dont have it. May be its so you take a ONE FULL MINUTE sitting in your broken truck to realize how much you appreciated it when it was running, well that will work. With the propper cable removed of course.

Thanks to all

The transmission problem sounds like a common one that many guys with a larger than 3000 RPM stall face, P0757 I think it is. You have to program the PCM to fix it. Allen is very familiar with this issue. I'm not sure how he fixes it but he's fixed mine.

Finally some good news, Allen will send out a new computer monday,
Left the positive off all night , No change. no code no light,
Thanks guys, Ill let you know if the new computer fixes it, or if i broke someting What an a$$ ache!!!!!!!!!!!!!!!!!:whack:

no DTC's... interesting.. was this first setup to use MAF?
i know before i converted to SD tuning, if i removed the MAF, but left
the wiring connected (IAT still functional) if get a P0101 or 0102.
do you have a MIL setup? usually also a P1870 FMC error occurs as the
"load" isnt complete so default full force (bang) shift to protect from
slippage. id get a stock no vats tune (leave the DTC's alone) to verify
issues.. and run the DTC's out in batches.

airdeano

Quote:

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Originally Posted by airdeano

no DTC's... interesting.. was this first setup to use MAF?
i know before i converted to SD tuning, if i removed the MAF, but left
the wiring connected (IAT still functional) if get a P0101 or 0102.
do you have a MIL setup? usually also a P1870 FMC error occurs as the
"load" isnt complete so default full force (bang) shift to protect from
slippage. id get a stock no vats tune (leave the DTC's alone) to verify
issues.. and run the DTC's out in batches.

airdeano

---

That is exactly Allens plan. 99% only tune for the mods that I have so that it will run, I guess a proven tune file that he knows is good. My mods are pretty mild and common. CAI, shortie headers, cam,spring p rods & shift kit / stall converter to match.

The ony time I ever got a bang shift or code was when the vss wire got pinched.
That was also interesting, because without the vss input that truck had so much more power, LOTTS more. It wound up pretty tight shifted hard (bang)
into third and stayed there. no down shift no tc lock. Shut it off....start back in first... repeat.
You could leave a stop in third gear no problem. But the increase in power off the stop in first gear was dramatic and also in third. I fixed it asap, but always wondered why it was so strong only then.. and not always... obviously it was/is capable.

so ???? no vss signal.. truck has more power????
and???No maf signal.. truck has WAY more power. (its gonna break the seat mounts) starts better, idles smoother.:eek: WTF I dont understand how its running at all. :duh:

I"m guessing that the file that is in the pcm now is junk or at least way way wrong for my truck. And the truck is a lot stronger than I thought. I can not imagine how great its gonna be when its tuned right. This bi polar electronic stuff has got to go.
I drove it with this tune for 18k miles and no issues till the other day, My buddy drove a brand new company pickup with a 5.3 , I let him use my truck to move and he could not believe how much better mine ran than the one he drove for months, he's a gearhead so he knows. Wait till i tell him my rig's been running like shit since i put it on the road.

Any new news on your shifting problems? I'm running into the same thing w/ my swap. Shifts fine at normal but WOT the truck just red lines and won't shift. I'm getting the p1870 code though. Just wondering if your new tune fixed it?

JBR, check this out... P1870 Trouble Code; "Transmission Componet Slippage" - Automotive Message Forums

and this ... My3cents.com - General Motors Informative - GM service bulletin about code p1870, GM service bulliten about code P1870

Red,
I've done the normal search for the code but I think I remember reading somewhere that the code can be kicked by a tune that's not right on the money. I could be wrong..... It's just something I read. New news on the truck though, I went for a drive today and now the trucks dead on the side of the road. It was driving fine down the highway and then nothing. Park works and every other gear is like neutral. At 1st look it's like the trans pump went out, like there's no pressure in the valve body. Now I'm wondering if a tune can be out far enough to kill a trans? I guess I'll be pulling that apart this week. Good thing I have vacation time saved!

I don't know about the tune crapping the transmission out. The first indication was you have a bad valve body. It could have killed the transmission. How many miles did you have on the transmission?

Quote:

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Originally Posted by duckmanjbr

Any new news on your shifting problems? I'm running into the same thing w/ my swap. Shifts fine at normal but WOT the truck just red lines and won't shift. I'm getting the p1870 code though. Just wondering if your new tune fixed it?

---

Several things have happened, I got my new tune from Nelson Performance and that did not solve the shifting problem , the truck performs better, pulls very hard, bit will not shift properly, Different Maf minimal change and new problem.
At a normal driving part throttle (no let up) It will only shift out of first at well over 4000 by it self.
It will shift to second sooner if I let off the gas.
It seems to shift 2-3 & 3-4 a bit high rpm but reasonable , much better if i let of the gas , drive it like a stick shift.
Down shifts back to first at 20mph.
Wot from a stop- good launch, pulls hard, red lines, bounces off the rev limiter no shift till I let off the gas - some times right to 3rd
Wot from the speed limit - down shift to first , pulls crazy hard till redline, no shift.
Definitely not slipping.
Running, starting, idling, cruising, all better & pulling harder with new tune
I spoke with Allen and he said to substitute a KNOWN good MAF and try that.
I BOUGHT ONE FROM A BONE YARD (bc i couldnt find a donor) not a KNOWN good one. and I still have most of the same problems, and a new one.
Hard to start. but the 2-3 3-4 shift is much better. that was today 8-23

So IDK WTF. other than my wallet is 50 lighter.

Keep in mind that I had ZERO problems with this truck ((other than only minimal performance gains based on the mods I have)) till I unpluged the MAF.

I thought and correctly that the truck should have more umph. Per opinion of other person, I unplugged the MAF, for a diagnostic check. Based on the results, They also said leave it un-pluged. The truck really came to life, had fun for that day and now just A$$ ache.

and you never got a P0101 MAF code or IAT code either...
did you do the brake/horn (clear the KAMS) thing?
what is this vehicle?
you need some data scanning... see what the sensors are saying to the
computer. some sensor is saying something wrong and at the inappropriate
time. do you have autotap or HPTuners?

airdeano

Custom car custom probelms. I dont think its the tune, But rather a mechanical problem and suggest your either take it in for a proper daig or find a donor tranny and see if it fixes it:p I know you didnt have any issues before unpluging the MAF, But its just a coincidence IMO. Your not always going to get a code and if you do dont read too far into them. There a good diag aid, but can be miss leading to the untrained eye or in certain situations and sometimes there just not there. Also go slap the dude around who told you to just leave the MAF unpluged permanently for a fix :thumbdown:

Quote:

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Originally Posted by airdeano

and you never got a P0101 MAF code or IAT code either...
did you do the brake/horn (clear the KAMS) thing?
what is this vehicle?
you need some data scanning... see what the sensors are saying to the
computer. some sensor is saying something wrong and at the inappropriate
time. do you have autotap or HPTuners?

airdeano

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No codes have showed up with this situation at all , from 2/3 weeks ago when I first un-plugged the MAF, thru miles of erratic shifting, 3 resets and battery disconnects over night, New computer Nelson tuned , swapped MAF, NONE!
I DONT UNDERRRRRRRRRRSTAND. :tantrum:

When the brake horn KAMS thing came up I responded with a question if that was only applicable to oem complete vehicles with bcm and other systems still intact or for swapped trucks also. I got no further input and since my vehicle is a swap i did not do the KAMS.

The truck is a 88 k-5 blazer 4x4 with a 2004 5.3/4l60e 212/218 cam, springs push rods, shortie headers, oem cats, dual 2.5 pipes, CAI, efans 180 t stat, trans go shift kit, TCI 2600 stall all Now Nelson performance Tunned.

I do not have a scanner or tunning software, and beyond my control
I am now flat broke can't get it or have it done for at least a month. But i got a new tune.:eek::duh::nutz: I am ecstatic about the tune , but I should have got it scanned first.:duh::nono:

The truck only set codes 5 times (since i got the bugs out) in the last 18k+ trouble free miles, I forget the # s and know its important but 1) tranny stuck in third, corrected itself when I restarted the truck happened twice about a week apart, that was at one month on the road,and not broken long enough to fix it. 2) vss wire got pinched , fixed wire. 3) lean bank one & 4) lean bank 2- both at the same time. fuel pump in tank connection.

I'm starting to wonder about, not necessarily a coincidence, or caused directly by, but related to the drastic performance increase when I unplugged the MAF, and That one time trany hic-up a long time ago.
I wonder if some thing is/was wrong/ loose/ stuck and waiting to change any way?

If I understand all of the input that I have gotten, ...... feel free to Jump in and stop me if this is not so.......

A certain tuner someone not on this site took the info and input I gave them concerning the performance of my truck. What I told them was this:
"I Think my tune is not quite right, I want to see about getting it changed"

He asked me "what I wanted him to change, as if I would know exactly what it needed or which table was off.
"IDK this info but I can tell you the basics of the problems"
"My truck runs much better before it fully warms up.... it feels stronger, shifts tighter, just all around better" then some more details on that subject. I also told them about "how much more power the truck had when the VSS signal was lost. but that was only from ignition start to the 1-2 shift point. and repeated after shutting the truck off" then some more details.

His diagnostic little mind was looking for or suspected something (what IDK) and he knew disconnecting the MAF would tell my motor it was -40 and pcm would adjust accordingly. and go into a closed loop. HE Told me to discon the MAF and call back with results. It felt as if the truck found at least 60 horse power. I said "much better"
He said any codes? NO CODES shifting ok shifts WONDERFUL, PERFECT he said leave it unpluged and drive it What I dont need it ? Well it could make the tran.......but.........no you said its shifting ok yea shifting good Ok leave it unplugged and let me know what you want me to change BTW he has not returned my calls

IDK what was off but the closed loop obviously ran better especially with the mods I have. He also knew it would do something not good with the transmission but never finished the word or the sentence or explained the possible/potential problem or what it might do or how it would act.

pure speculation and assimilation of gathered info on my part ............

The closed loop function, and the Increase in line pressure, a few really fncking cool WOT shifts, gobs of torque, for a few miles have dislodged/jammed, plugged up, or completely has broken something. That one time long ago tranny hic-up may be involved. But what or how or even if IDK

Any thoughts ?
Thanks guys your all I've got.

What kind of harness are you using? I'm using a NP harness and am having the same type of problems. I pulled the trans and replaced w/ a new one thinking it was a bad trans but 200 miles later I'm back in the same boat and now I'm back looking for a computer or a wiring problem again. Both my trans went bad around 200 miles so I'm REALLY REALLY leaning away from it being a trans problem! My second trans was a known good trans and I was only borrowing it so I really hope it's not @#$-up now! I'll be buying 2 new trans if I screwed that one up! I've gotten all my swap parts from Allen (computer, harness.. etc) but am still having this major issue! I have a really hard time swallowing 2 bad trans in 400 miles and it not having anything to do w/ the computer or the wiring!! Both trans just act like there is no hyd. pressure in the valve body.

Hey man that sucks, Dont feel like the Lone Ranger, My truck has bounced off of the rev limiter so many damn times that its making horrific noises now. Scarry ones. I think Its hurt bad. Remember how cool it sounded when you put playing cards in the spokes of your bike. That sound is not cool coming from your 5.3. NOT AT ALL. That thing will down shift to first at any speed when ever it wants.

Ok My harness is a oem that I modified my self, No trouble with it for 18k miles. My new tune (1week now) is from Nelson Performance.

I am not an expert

If you are certain that you installed the proper torque converter correctly its common to foul the front pump seal and have fluid flow thru the cooler no blockage and enough fluid, then I think you should eliminate the wire harness, by checking the wires for continuity to the proper pins on the trans connectors and the designated pcm connectors. Wiring diagrams, pcm pinout, multi meter, alligator clip jumpers and some thin wire like a paper clip, Take your time and check. Go easy dont damage the sockets and dont pierce the insulation.

I have been doing some research and have found that crane cams requires that the map values be reset so that the lack of vacume doesn't set the check engine light off. I would surmise that to be the same with all manufacturers. I'm not a tuner or a drive ability diagnostic expert nor do i know how to spell very well, but i can read and follow along and learn quick.

The MAP sensor is just a electronic vacume guage.
Used to be that manifold vacume was sent directly to a vacume modulator on the trans, the trans used actual vacume to shift. Well now the MAP tells the PCM electronically how much vacume there is and the shifting begins. Oh remember the cam and the MAP values are changed. Enter the TUNING EXPERT.

My problem seems to be a dieing MAP sensor,:( Not dead enough to set a Code (by THE re determined values) :duh: but bad enough to not tell the pcm its time to tell the trans to shift. :eek: :bash:

The MAF and the MAP work together, Apparently when I unplugged my MAF the MAP compensated for a short time. But the Map has less to do with air fuel ratio


All of these sensors have outputs related to inputs mostly 5 volt , Any body who can read a volt meter, follow a pin assignment, and had basic electric 101 could trouble shoot a problem IF IF IF only the values were readily available, but they are not or very hard to find.

the following is some of what i found while searching sorry the pics didnt show up. apparently its from a student workbook.

Automatic Transmission Electronic Controls




Student Workbook
















This workbook is designed to help you to gain a working knowledge of the operation, diagnosis and repair of Electronically Controlled Automatic Transmissions used in General Motor’s cars and light trucks. Toward that purpose, we will be assigning you a number of different exercises that will test your ability to diagnose these vehicles.

CAUTION!

Extreme care must be exercised when working on or around automatic transmissions! Hot components such as exhaust pipes and catalytic converters must be avoided or serious injury could result!

Course Objectives:

Understanding the operation of transmission electronic controls.

Diagnosis of transmission controls with a DVOM and a Tech 2 scan tool.

Repair procedures for electrical and electronic transmission concerns.
Course Focus:

The course will focus on Hydramatic 4L60-E and 4L65-E transmissions and 4T65-E transaxles. Many of the diagnostic procedures will be similar for other current Hydramatic transmissions and transaxles.

Transmission Controls:

All General Motors current production transmissions and transaxles are controlled by the PCM, or power train control module or, by a TCM or transmission control module.

Types of Transmission Controls:

Shift pattern, or when a transmission makes upshifts and downshifts, and …

Shift quality, or how soft or harsh a transmission shift feels to the customer.

How the PCM controls the transmission:

PCM’s command the shifts based on data received from sensors called “Inputs”. The PCM will then use that data to calculate when to shift the transmission and also how to make the shift “feel” i.e. soft or harsh. The PCM will also control the shifts using critical

controls called “Outputs”.














Transmission Inputs:

Speed sensors

Pressure switch assembly (PSA)

Transmission fluid temperature sensor

Neutral safety back up switch (NSBU)

Throttle Position Sensor or TPS

Mass Air Flow Sensor or MAF

Manifold Absolute pressure or MAP

Coolant Temperature Sensor or CTS

Brake switch input

These sensors all play a part in telling how and when the transmission should be shifted, or the torque converter clutch applied, by the PCM.

Transmission Outputs:

1-2 shift solenoid

2-3 shift solenoid

TCC/PWM solenoid

Pressure Control Solenoid (PCS)

3-2 downshift solenoid

TCC apply solenoid
Input operation: Speed Sensors


Speed sensors send an A/C signal to the PCM that varies with transmission input speed and vehicle speed. The 4L60-E does not use an input speed sensor, they use the engine RPM signal from the ignition system. The PCM uses speed sensor signals to control transmission upshifts and downshifts.


























Input operation: Pressure Switch Assembly


The pressure switch assembly (PSA) monitors the position of the transmission’s manual valve. The PCM uses PSA data to control shifts based on the driver’s inputs to the shift lever control manual valve.



















Input operation: Transmission Fluid Temperature Sensor (TFT)

The PCM uses the Transmission Fluid Temperature (TFT) sensor to help contriol shifting and Torque Converter Clutch (TCC) apply. Cold temperature may inhibit some upshifts or TCC apply. Hot temperatures may cause early TCC apply and earlier than normal shifting.








Input operation: Neutral Safety Back Up Switch (NSBU)

The Neutral Safety Back Up switch can give input on all or some of the following:

Park or Neutral selection for starting

Driver commanded gear range

Back up lamp control







Input operation: Throttle Position Sensor (TPS)

The Throttle Position Sensor (TPS) sends a signal to the PCM detailing what is happening with the throttle. The TPS can show if the customer is accelerating, holding steady throttle or decelerating, along with the rate of acceleration or deceleration. This information is critical to help the PCM select the proper gear for smooth operation.


Input operation: Mass Air Flow Sensor (MAF)

The Mass Air Flow sensor signal is used by the PCM to determine the load that is being placed on the engine. The engine load data is used by the PCM to control shift timing and shift feel.




Input operation: Manifold Absolute Pressure Sensor (MAP)

The Manifold Absolute Pressure (MAP) sensor signal is used much the same way as the MAF sensor signal, the MAP senor signal tells the PCM an indication of engine load. The PCM uses the MAP sensor data to control shift timing and shift feel.








Input operation: Coolant Temperature Sensor (CTS)

The Coolant Temperature Sensor (CTS) signal is used by the PCM to modify shift and Torque Converter Clutch control. The CTS signal is also used by the PCM to help very that the Transmission Fluid Temperature signal reading is accurate.


Input operation: Brake Switch Input


The Brake Switch Input is used by the PCM to control the release of the Torque Converter Clutch (TCC) when the brakes are applied. This feature allows for a smooth deceleration when coming to a stop.
Input operation summary


Inputs supply information that the PCM uses to control transmission operation. Many transmission concerns may be caused by failed input sensors or failed sensor circuits. The thorough understanding of PCM inputs is critical to correct transmission diagnosis.
Output operation: Shift Solenoids


The PCM grounds and un-grounds shift solenoids to control shift valve position in the transmissions’ valve body. Shift valve position determines which gear range the transmission will operate in. When the PCM grounds a shift solenoid, the solenoid closes a hydraulic exhaust path. The hydraulic pressure then forces the shift valve to the up shift position. By using two shift solenoids, we can provide 4 forward gear ranges.







Output operation: Shift solenoid control


All 60 & 65 series transmissions (4L60-E, 4L65-E, 4T60-E and 4T65-E) share the same solenoid operation. They used a 1-2 and a 2-3 shift solenoid, each with two postions, giving us four gear ranges. The PCM uses shift solenoids to control “shift pattern” or when the transmission shifts.






Output operation: Shift solenoid status


1-2 shift solenoid on, 2-3 shift solenoid on = 1st gear

1-2 shift solenoid off, 2-3 shift solenoid on = 2nd gear

1-2 shift solenoid off, 2-3 shift solenoid off = 3rd gear

1-2 shift solenoid on, 2-3 shift solenoid off = 4th gear
Output operation: Gear ranges


1st gear: 1-2 on, 2-3 on

2nd gear: 1-2 off, 2-3 on

3rd gear: 1-2 off, 2-3 off

4th gear: 1-2 on, 2-3 off

























Output operation: Torque Converter Clutch Pulse Width Modulated Solenoid (TCC/PWM)

The PCM uses the TCC/PWM solenoid to control when the torque converter clutch applies and how soft or harsh the TCC apply feels to the customer. The TCC/PWM also controls the release feel of the torque converter clutch.









Output operation: TCC apply solenoid


Some older model Hydramatic transmissions and transaxles used only a TCC apply solenoid. These older transmissions and transaxles may have used an accumulator to “cushion” the TCC apply feel. Some models of the 4L60-E transmissions have used both a TCC apply solenoid and a TCC/PWM solenoid to control torque converter clutch operation. The PCM provides the TCC apply solenoid with a ground to complete the control circuit. When the TCC solenoid is energized, the hydraulic vent is closed and hydraulic pressure moves the converter clutch valve, applying the TCC.

















Output operation: Pressure Control Solenoid (PCS)

The pressure control solenoid (PCS) is used by the PCM to control what is known as “line pressure” inside of the transmission. The PCM controls the PCS based on data received from the various transmission inputs. The PCM controls the amount of amperage to the PCS. The range of that amperage is .1 amps to 1.1 amps. The higher the amperage, the lower the line pressure. Conversely, the lower the amperage supplied to the PSC, the higher the line pressure. The PCM controls line pressure with the PCS based on inputs such as engine load, TPS reading, MAF or MAP sensor, engine speed or VSS signal and RPM signal. The PCM is also able to compare desired shift times to actual shift times and adjust the PCS current accordingly. The PCM can maintain shift quality over the life of the vehicle by adjusting PCS amperage to control shift times at “new” vehicle levels. If the PCS control signal is lost, the line pressure goes to maximum to prevent internal transmission damage.
Transmission Electrical Diagnosis

Electrical problems in automatic transmissions can store a DTC or Diagnostic Trouble Code. Electrical problems in transmissions can cause inappropriate operation and customer concerns.
Code types for automatic transmissions
Circuit Codes


Circuit codes set when the solenoid circuit or sensor circuit is electrically open or shorted. The PCM detects the electrical fault and stores the proper diagnostic trouble code (DTC).
Performance Codes


Performance codes are set when the PCM commands an action and that action does not occur, i.e. no 2-3 up shift. The PCM has already verified the integrity of the electrical circuit and has found no electrical fault that would cause the problem. Performance codes are usually an indication of a mechanical or hydraulic problem.
Diagnostic Tools


Use of these tools will make electronic transmission diagnosis very straight-forward.


















Tech 2




















J-39200 Fluke DVOM


















J-44152 Transmission Test Harness




















J-35616-B Terminal Test Kit





Hydramatic Standardization




All Hydramatics share a common wiring design. This allows for ease of diagnosis. Pin “A” is the control circuit for the 1-2 shift solenoid. Pin “B” is the control circuit for the 2-3 shift solenoid. Pins “C&D” are used to supply current to the Pressure Control Solenoid (PCS). Pin “E” is the 12 volt supply to all of the transmission solenoids. Pin “L&M” are the transmission fluid temperature sensor wires (TFT). NOTICE! Make sure that you recognize which end of the harness you are working with! Mixing up of the transmission connector pin-out with the harness pin-out will result in misdiagnosis!
Troubleshooting Tips


Most circuit codes are limited to the two wires and the solenoid, don’t over complicate the diagnosis! Use the functions of the TECH 2 to the fullest, especially for controlling things like commanded gear and actual gear. If multiple codes are stored, look for common causes such as poor grounds or power supply problems. Don’t rule out that a concern with a circuit could be in the internal transmission electrical harness. Many intermittent electrical problems can be caused by chaffing of the transmission external wiring harness.


Automatic Transmission Electronic Controls

faulty/ intermiten connection at MAP sensor connector. not making full contact with signal wire and corresponding pin of sensor.

Man I bet you feel better. congratulations.

The shifting issue sounds like a vss, make sure that the pcm is recieving the signal, if so, swap out the vss with a buddy, they are cheap and easy to swap, one bolt does it. When I did my '94 swap, my trans wouldn't shift, like yours, the vss was bad.
The high ltrims (the pm you sent me) are probably bad o2's, or a vac. leak.
The pcm will try to add more and more fuel until it can't, then set the 171 codes you mentioned. The best way to detect is to hook up a leak detector, like a smoke machine, and find the leak. When you get hptuners, you can determine if the o2's are toggling properly, they should toggle from 50mv to 900mv, if not, they are bad.
If they hang around 400-600, they are bad, if they are 0mv, check the wiring.

The maf definitely needs to stay plugged in. If you haven't swapped that yet, try it, but I think you said you bought a new one. The maf will cause harder shifts, but i don't think it will cause it not to shift like you're describing, that's the vss signal or vss going bad.

hope this helps,
allen

Quote:

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Originally Posted by duckmanjbr

What kind of harness are you using? I'm using a NP harness and am having the same type of problems. I pulled the trans and replaced w/ a new one thinking it was a bad trans but 200 miles later I'm back in the same boat and now I'm back looking for a computer or a wiring problem again. Both my trans went bad around 200 miles so I'm REALLY REALLY leaning away from it being a trans problem! My second trans was a known good trans and I was only borrowing it so I really hope it's not @#$-up now! I'll be buying 2 new trans if I screwed that one up! I've gotten all my swap parts from Allen (computer, harness.. etc) but am still having this major issue! I have a really hard time swallowing 2 bad trans in 400 miles and it not having anything to do w/ the computer or the wiring!! Both trans just act like there is no hyd. pressure in the valve body.

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If the trans is shifting, the pcm is doing it's job and the harness is doing it's job. I'm sure it's shifting because you got to at least drive it and you didn't mention shifting issues.
Transmissions can be a pita. If there is no pressure, maybe check the wiring, something might have gotten pulled out, maybe a pin not seated right in the harness, but we pin out every harness and double check them.
The pcm would have to be setup to remove all line pressure on purpose for there not to be line pressure, that would be just out right wrong to do.

I've seen customers go through 5 transmissions before, claiming each one was built to handle 1,000hp. That isn't your issue here, power, but transmissions are tough to deal with sometimes.

This may be an expensive question, but do you have an extra trans you can get or borrow, and a new converter, maybe something is being transferred from one bad trans to the next.

good luck and let me know if you need something on my end,
allen

(btw, try pm'ing me because all your emails go to "Junk" email everytime you email me)