limp home trans

have a very specific problem. the trans in my 99 s10 (4l60e) is apparently in limp-i/home mode. from what ive read, this is caused by a loss of power to the trans or a bad pcm/vcm. we b/d the truck and relocated the ecu and fuse box under the dash. trans shifted perfect b4. i am 95% certain that i have all grounds connected and all that was done was rerouting of the harnesses no cutting or splicing. ive found several wiring schematics for the trans but a couple were different. i need the help of a GM tech if possible. the diagrams i have show lettered pinoputs of the plugs but the plugs on the trans(range module and the other two harnesses) dont corrolate to the letters on the trans side. maybe the letters are on the ecu, but trying to troubleshoot without cutting the whole harness open again. other symptoms are the oil pressure gauge is pegged out (passed 80) and the prnd321 indicator light works when sitting at idle but goes off once moving. the trans has only 2,3, and reverse and gets very hot. i read that this is limp in/home mode and it causes the line pressure in trans to stay high. missed taking her to unite after an all nighter because of this.if u know a tech maybe they could help. sucks having a b/d truck for the first time and being unable to drive it. also no, i havent had it scanned yet. just want to see if i could get a pinout of the actual connectors at the trans. thanks for any help or suggestions.

This just sounds like a ground issue to me..I have had similar issues with a 4l80 trans...I would say go over all your grounds again. Another thing to check is your vehicle speed sensor.  If you can please provide a lil more info too, like what engine you have and your vin. I'll try to help as much as i can!

4.3 v6. i was thinking the vss may be the cause. i saw a grounded shield on the twisted pair in the diagram and think i may have to track that down. just not certain where the vss is mounted on trans. i think its on the trans but not certain exactly. there is a sensor on the tailshaft but again without a specific trans diagram i'm not sure what it is

Whats your vin...I'll try to do some more research

Double check that yiu have all your plugs in the right plug. Most everything can only go to one place, but gm threw me a curve and used the same plugs in the harness, that i switched when putting in  my dash.. I had issue ith not getting a reading forObd II and my stereo speakers werent getting a signal and some other wierd  stuff. I ended being two plugs that  were identical got switched  under the dash. Mine seemed like a ground too,  and it was too, but it was because of the two plugs i crossed. Unfortanetly mine is a fuulsize but i thought i would share my problem with you, possibly might help. Wiring is a PITA.

thats what im leaning towards. may have to bite the bullet and pull the dash back out. just a lot of wire en mass under there now, seeing as the engine harness is now under there with the normal dash harness. sucky!

if its in limp mode, there should be codes in the computer, they will help point you in the right direction. otherwise it could be a number of things, you're just guesing and trying to find a needle in a hey stack... 

Edited: 6/7/2009 10:43:41 AM by maniacalmini

we eliminated the airbag module that was under the seat(removed whole system actually). also removed the abs manifold and controller. has regular power brakes now. not sure if completely removing abs stuff would cause a break in any circuit that would cause the trans to go into this mode. anyone have any other ideas or similar experience, if so what was the remedy?

not a chevy but my 01 f-150 jumped in limp mode and all it was was a damn fuse! and the shitty part was it took me a week to realize it.

think we figured out what went wrong. apparently we managed to swap the only 2 weather pack connectors in the whole truck that are interchangable, the trans harness connector and the brake pump connector. putting her together now then see what she does. always something stupid!lol