* Please help! 4L60e shift problems after 5.3 swap into OBS *

[droopyzda1]

Hey guys hopefully someone can help me out on this issue I have. I recently swapped in a 5.3 in my 1994 C1500 W/T. It had a tired 4.3 in it. The motor turns on, is healthy but I am having trans issues. I moded the oem engine harness with emissions deleted and wired it up using lt1swap.com as well as having Brendan from that website remove the VATS. I am using my 1994 trans (because of funds) and he also deleted the PWM from the pcm because the 1994 trans does not have it. Before I found out he deleted the PWM, I changed the internal harness of the trans to that of a '96 and later because it has an extra pin in the plug for the PWM (I still have the original one). All my gauges work including the speedo ( I have no tach from the factory though). I have checked the trans fluid level and it is where it should be at operating temp. Now here is the trans problem. When in OD or D it does not start off in 1st gear. Instead, it starts off in 2nd gear then when you think it should shift to 3rd, it shifts to 1st. It stays in first and does not shift until I slow down to a stop then I can take off again but in 2nd. If I go to L2 or L1 its in 2nd gear all the time. Reverse works fine. I have the OBD 2 plug and hooked up the scanner and no codes even after I drove it locally for about an hour. But then again, since its a weekend driver, and for antitheft reasons, I disconnect the positive terminal and the fuse for the power on the harness. Please help !!

[ls1ram]

My first GUESS is that you might have the shift solenoid wires crossed over to one another...I had a friend who did this and all I can remember is it shifted funky, this may or may not be the issue but those two solenoids that look the same control 1st, 2nd, 3rd, and 4th are very close to each other so I can see someone crossing the connectors for them.

In 1st gear both solenoids should be ON, second gear turns on off, then third will shut both off, then in 4th the opposite one for second gear will turn back on.

you also might want to compare pinouts for both wiring harnesses and make sure that each wire goes to its designated solenoid. I'm not sure if one harness is pinned differently to the other harness but that seems to be my first tip for you. Let me know what you find and if you cannot figure it out let me know, I will look at some pics of wiring diagrams a well.

Also post up pics when you pull the pan..

Oh and does the computer see RPM? and MPH? On a LS computer it sees RPM from the Cam sensor so make sure this is plugged in cause it will run without it plugged in. And the MPH is off the electronic speed sensor....The best way to test both is to have a scanner (some hand helds will work) and quickly monitor and make sure the computer registers rpm and mph...the trans needs both to shift...your dash speedometer is electronic or cable?

[droopyzda1]

Here is the trans valve body pic:

[droopyzda1]

The speedo is electric and works. I connected it straight to the pcm. I used a free torque app on my phone and Bluetooth paired it with an obd2 connector and saw that my rpms do work. No codes have come up for anytging. Would a bad cam sensor make a code? I have pieced together this swap. Is it possible I may be using a 4x4 harness? I do not have any extra plugs left over though on the harness though.

By the way. This transfer had a small seaping leak on the rear seal where the drive shaft connects before I did the swap. After everythingws put back in, the leak seems excessive. It is leaking from the VSS to. Could that be part of the problem also?

[ls1ram]

Well, before you chase a ghost, try to hook the obd2to a scanner and see what gear is being commanded if u can ...what extra plug?

[shmiet]

Make sure the PNS switch is aligned properly. If it is mis-aligned the tranny will not function properly.

[droopyzda1]

Sorry I have not posted recently. It was a rough few months for me and my family after my mom was not able to be treated any more from ovarian cancer and was set home with hospice care. She passed away peacefully a few days after Christmas. Well I am back on this project and it is helping me cope with my big loss.

As far as my old 4L60e, change both solenoids an found out 3rd and 4th clutches were shot after the previous owner told me the trans was fine. I should have suspected the worse when I bought it not running. But then again I paid only $260 for it so its all a learning experience thus far. I found an '03 Silverado 4L60e that a guy was in need to sell after he did his 6.0 4L80e swap and after advertising it on craigslist for $300 I snatched it up for $150. Trans fluid was clean and no clutch material in the pan. I changed the rear seal and front seal by the pump and changed the rotor with the 13 or so keys and installed a corvette servo while I was at it and changed the VSS plug as well. I dropped the old trans and was installing the '03 when I forgot to seat the torque converter properly. Thank goodness I did not tight the bell housing bolts or I would have to open the trans and replaced the rotor again !! I mounted the trans bolted everything up and started the truck. It felt like the engine had a load on it cause it shut off a couple times on me. I had the wheels chocked and I could feel the truck wanting to move forward while the gear indicator said it was in park. I did delete the PRNDL switch from the trans cause I have a mechanical shift indicator. Well for some reason, the shift pattern is reversed !! Park is now in D1 and park was in L1 !! I had to shift it to R for Drive. Trans runs great and goes thru all the gears nicely. Maybe I have the shift linkage on wrong ? Also I had Brendan from LT1swap.com do my tune. He simply removed the vats and had tuned it so I could run my older 4L60e which did not have PWM. Would I have to send it back to him to add it back on ??

[GMCwantsLS1]

You don't need PWM. If the pattern is reversed than you may want to check the linkage setup. If memory serves right park is all the way forward (the linkage pin is torward the front of the vehicle).