djss

Well it looks like our hope to ride our 60 Impala on the power tour this year is fading fast.

It is a 2002 LM7 4L60E out of an 02 2wd Avalanche. BP automotive harness and PCM reflash.

When in drive it is trying to pull out in I think 3rd. If you pull it down into low it will shift to low but will not change gears. I took it to a GM dealer who is a friend and they pulled the pan and checked voltage to the solenoids and everything checks out. They went ahead and replaced the solenoids just to be sure, the service manager and both transmission guys now say they are 100% sure the problem is not in the transmission. They are telling me the solenoids are activated by ground and the 1-2 solenoid is getting ground like it is supposed to but the 3-4 solenoid is not. They also checked the pins in the harness and see sure that the problem is not with the harness. I hate to keep spending money and replacing parts.

I'm pretty bummed with the whole thing at this point. I really thought it would have been running a month ago. It still has an oil leak (front seal), no exhaust, a/c hooked up and the front end aligned.

Mike_hawk

Sounds like the trans is in limp mode, usually it has something to do with the pedal/tac if it's drive by wire. Is the engine/trans/harness/computer out of the same vehicle? The 4l60e/4l80e have the same plug but it's wired differently so that may be an issue as well depending what harness you are using.

djss

The engine transmission and pcm are all out of the same vehicle. 2002 Avalanche. The wiring harness is from BP automotive and BP also reflashed the PCM. It is drive by cable.

gofastwclass

iTrader: (2)

If the transmission feels like it is taking off in third and won't shift I would guess you don't have power to the transmission through the harness. If I remember properly, third gear is the default gear on a 4L60E when there is no power to the solenoids.

The harness will have a round plug that has one pink wire. This pink wire should have 12 volts with the key on and everything is enabled by ground through the PCM.

It could be as simple as a fuse or as complicated as a wiring issue depending on how your harness was built. Obviously I hope it's a fuse.

By the way, your comment "They are telling me the solenoids are activated by ground and the 1-2 solenoid is getting ground like it is supposed to but the 3-4 solenoid is not. They also checked the pins in the harness and see sure that the problem is not with the harness" only leaves one option. If the 3-4 solenoid isn't getting a ground signal the problem can only be in the harness or the PCM. The GM Techs say the harness is good it must be in the PCM. If you have a spare PCM you could try that - even though they rarely go bad, I've actually had it happen (for a coil) but you probably don't one laying about.

djss

Thanks for the info, the pink wire has 12 volts with the ignition on. The service manager and both GM techs feel it is in the PCM and you are right I do not have one laying around.

superdave84

Just had this problem a few days ago. For me it was a bad transmission fuse in the underhood box. Funny thing is, the fuse did not look blown. Replaced it and everything was perfect.

djss

Thanks, I will check that right away.

wbwhiteboy

iTrader: (10)

Do you have a RUN/START 12v source hooked up to the black C100 connector on pinout C?

djss

Yes

Also no blown fuses.

gofastwclass

iTrader: (2)

Too bad you aren't closer, I do have a spare PCM and HP Tuners we could use to verify.

Leadfoot85

iTrader: (3)

Check the TSS sensor. Had the same problem with my swap. It would shift through gears manually, but when in Drive it would stay in second. Worth a shot!

djss

Ok it appears to be shifting now. I drove it in the parking lot this morning and it is shifting, I need exhaust and the front end aligned to get it out on the road.


It appears my PCM was programmed for a 4L80E and not a 4L60E. A 4L80E does not have the 2-3 shift solenoid so the computer was not sending the proper ground to the 2-3 shift solenoid, or at least that is the way it was explained to me.

I appreciate all of the help.

djss

We got the exhaust on and the front end aligned yesterday and I drove it about 25 miles. Still have a whole list of little things to do, but it is running and driving.