98 Suburban 4wd 5.7 to 01 6.0L questions

Been lurking for years and have learned a lot, but not enough!

I'm in the process of putting a 6.0L in my 1998 Chev Suburban 4wd. I was planning on removing the stock 5.7 computer, pulling the required pins from the old harness and placing them into the 6.0L computer harness.

I'm at the point where I'm pulling the pins from the old harness when it dawned on me that I have NO info on what pins I need to pull for the 4wd system! Or can I even do it. Maybe I'm stuck with using both computers because of the 4wd?

I have a stand alone harness for the 6.0L ready to go....

Please advise:)

A few down from your post
http://www.ls1truck.com/forums/lsx-t...rger-swap.html

peace
Hog

I looked through that whole thread and saw nothing about the 4wd issue I have, am I blind? I have the same info that thread has on pulling pins, just nothing about the 4wd.....

Depending upon what you have, you will need to run either one or two wires to the new PCM.
The following are for Suburbans without Auto Trac

Circuit 1694, gray/black wire, pin 23 of C-4 connector
Circuit 1695, black/white wire, pin 19 of C-4 connector

The following is for Auto Trac

Circuit 1694, gray/black wire, pin 23 of C-4 connector


Circuit 1695, Black/white wire, is the front axle switch wire and goes to pin 19 of the C-2 connnetor(red or green, depending on year) of the new PCM
Circuit 1694, gray/black wire, is the 4 low signal wire and goes to pin 16 of the C-2 connector.

A small reworking of your stock 97 harness with the addition of 10 wires will run the Gen3 engine. You don't need a stand alone harness or two PCMs.

Jeff

I understand that the old computer will run the LS engine - I have HP tuners and I've already licensed the LS computer, to use the old computer I'd have to license it for another 100 bucks. Would the extra 100 bucks and adding the extra 10 wires be easier than using the LS computer in my case? I do have another stock LS harness that I could salvage the extra wires and connectors from. I believe I have the auto transfer case - I need to check for sure....

The 98 Black 4 plug PCM will not run the Gen3 engine. What you would do is repin the 98 harness for the Gen3 PCM and install the additional 10 wires to the harness. There are a few wires that also need to be lengthened. I got your P.M.

Jeff

Got it - I was thinking backwards! I assume that I would just remove the old injector harness plug and add in the new style connectors for each cylinder....

I'm pulling the old engine today and going to try to install the 6.0L, thanks for your help

Yes, That is one of the things that needs to be done.

Jeff

Do you have the info I need to do the harness conversion? I'm liking this idea much for than merging the two harnesses or running two computers.

Check your e-mail. It is already sent.

Jeff

What does the acronym CMP and CKP stand for?

Quote:

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Originally Posted by genIIIdude

What does the acronym CMP and CKP stand for?

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CMP = Cam Position Sensor. CKP = Crank Position Sensor.

Jeff

Thanks - another question - I noticed that you did not mention adding in the LS MAF connector - are you implying that I use the old 5.7 MAF and IAT?

Quote:

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Originally Posted by genIIIdude

I noticed that you did not mention adding in the LS MAF connector

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Hhmmm, You're right. Thanks for pointing that out. That is an oversight on my part. You should use the 5 wire MAF. I will add that to the file.

Jeff

No problem - This wiring stuff can be a nightmare and I appreciate your help!

Well - removed all the wires from the old 98 Vortec C1, C2, C3, and C4 connectors and got them pinned into the new Vortec C1 and C2 connectors - It wasn't that bad at all. I then removed the injector wiring, coil wiring, CKP, CMP, and MAF connector ends from an old 6.0L harness. Didn't get them connected into the old harness yet, maybe tomorrow night. Thanks Lextech!

What are you guys doing for exhaust on your conversions? I noticed that there is ample room on the drivers side between the frame and transfer case to run a true duel system - has anyone done this on an OBS?

Another question - How are you guys adapting into the OBS fuel lines?

Ok - It's alive! But I have a few issues - none of my factory gauges work, I'm thinking I need the factory 5.7 sending units - maybe I missed that?!

The LS computer doesn't send the correct fuel level signal for your cluster. You need a fuel segment swap with your tables flipped. Your engine coolant temp signal will come from the original sensor that was in your 5.7- I suggest turning it down and using an M10x1.5 die so it will fit in the place where the head coolant plug is. Fuel pressure gauge can be hooked up to the LS pressure sensor. PRNDL will need splicing-i couldn't get mine working fully yet.

Thanks - I'm sending my computer to Lextech for the fuel gauge issue - he also told me to run the 98 oil and water temp sensors to get the gauges to read.

My LS oil sensor had the same plug(single wire) as my obs sensor. I just plugged it in and it reads fine. Dunno if I got lucky or something haha
Good to hear your on track though!

The oil sensor connector on my truck has 4 wires?

4? Maybe suburbans are different

Just put the OBS oil sensor in (3 wire by the way, not 4) and still no oil pressure on gauge. Also - the fuel pump runs all the time now - I unplugged the new OBS oil sensor and the fuel pump turns off?! What gives?

i had this issue also. turned out to be a bad oil pressure sensor (i hooked it up incorrectly and fried the contacts shut) which caused the pump to run continuously. the way it works is you have the pressure switch in parallel with your fuel pump relay. when you turn the key to on/start, the pcm will kick the relay on for 2 seconds to build the needed fuel pressure at the rails. The engine fires and now oil pressure has been created and obviously stays until engine get shut down. this pressure closes the contacts in your oil pressure switch which alows voltage to power your fuel pump continuously until pressure is dropped. This is why you can still hear your pump running in the tank for several seconds after you kill the motor. takes a bit for the oil pressure to bleed down and open the contacts in the oil pressure sensor. I believe its also a safety precaution in case of severe accident like a roll over.... do you want your fuel pump stil running after you roll over and are unconcious just cuz your key is still in the ON position? i sure dont!!! :eek:

anyway, i know all this cuz i was having a similar issue and had to dig through all the wiring diagrams. makes complete sense to me now and i opted to keep it wired that way. some guys delete it but i personally like the extra safety. so it sounds like you have it wired incorrectly AND/OR your sensor is shot like mine was. i think it was like 10 bucks at autozone. cheap thing to replace.

BTW, im sure youve figured it out by now but ill say it anyway. The sensor doubles as a oil pressure sensor AND fuel pump switch. thats why there are 3 wires on it.

TAN - goes to oil pressure gauge on your cluster
ORANGE - +12v going to one side of contacts on switch
GRAY- comes off of other side of contacts of switch and goes to fuel pump


PHEW!! hope that helps

P.S. i drove around for a week having to get out and unplug the fuel pump everytime i parked somewhere before i figured this out....:sigh:

Another new sensor - fuel pump shuts off but still no reading on the gauge. hooked up a manual gauge to make sure I have pressure, all is well there. Going to chase down the wiring now....

Found my problem - I had removed a plug that is located behind the glove box and goes into the engine bay through the fire wall, well, that is where the instrument panel is grounded. The only reason I removed it was to get the stock wiring harness out of the way for my install. Both water and oil gauges are functional. The tach also works but is about 600 rpm shy of reality. How do I fix that? Can I do it with my HP Tuners?

I had a thought with my fuel gauge issue, and yes I know it may be extreme. I'm thinking of getting a newer fuel tank from a Suburban to replace my 98's. That way I'll be running the newer fuel tank and fuel pump assembly and should have no issues with the LS ECM reading the fuel sender. The only issue that I see could be that the stock 98 gauge would still not read the info coming from the LS ECM - does anyone have any experience with this?

I did drive it up the road the other day - this 6.0 has a lot more power than the old, tired 5.7! Thanks Lextech for your help with the wiring - retrofitting the stock 5.7 harness to the LS engine is the way to go......For me anyways.

Quote:

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Originally Posted by genIIIdude

I had a thought with my fuel gauge issue, and yes I know it may be extreme. I'm thinking of getting a newer fuel tank from a Suburban to replace my 98's. That way I'll be running the newer fuel tank and fuel pump assembly and should have no issues with the LS ECM reading the fuel sender. The only issue that I see could be that the stock 98 gauge would still not read the info coming from the LS ECM - does anyone have any experience with this.

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I have never tried that, BUT, I don't think so. The issue is not the PCM receiving info from the fuel sender. The issue is the PCMs output to the gauge. It needs to be changed in the tune.

Jeff

That's what I figured, or we'd see more people going that route. I'll have to get my tune changed back to a MAF and then send you the computer, and at the rate I'm going that could be awhile!

What about my tach? Is there a way to change it's parameters in the ECM with HP Tuners?

Quote:

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Originally Posted by genIIIdude

What about my tach? Is there a way to change it's parameters in the ECM with HP Tuners?

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should just be adding a resistor. worked for me.

http://lt1swap.com/lsx_tach.htm

That's what I needed - Thanks.....

Well finally got the tune figured out and everything is working well. I hadn't really driven it until tonight after a tune session and noticed the speedo doesn't work!? It reads on my computer while scanning but not on the gauge, any suggestions of where to start? Thanks....

depends how u hooked it up. are you using the new pcm to control it or did you leave the speedo hooked up the way it was? im guessing your using the new pcm. in that case its probably a matter of it being in the tune or something to do with your vss signal.. im leaning towards vss wiring because if it was a tune issue, either its not calibrated at all (unlikely) or there is a wiring problem...

this is just guessing since i dont know exactly what you did. post a little more info

I corrected the tire size/gear ratio in my tune, but still no speedo. Also, after I reprogrammed, the tach doesn't register at all now. Any thoughts? I'm running the LS PCM only....

On your stock harness at the PCM connectors---The wires at C4-3 and C4-4 need to be connected together and installed to the 0411 PCM C2-50.

Jeff

Just checked that connection - it was loose for some reason ??? - re-connected it and now she works. But, now it's throwing a p0706, transmission selector switch. Go figure, fix one, gain another! Any ideas on this?

How did you make out with this project?

Well - been driving my conversion for almost a year now, put about 13k on it. I couldn't be happier with the results - power is great and mileage is awesome, 12 around town and 18 on the freeway!