Engine/Transmission (1998.5 - 2002) Torque converter refuses to lock

[PVanderlugt]

Hey guys, need a little help. Goerend transmission with about 80k on it, noticed the other day cruising down the highway that the rpm was a little high for the speed. Looked like the TC did not lock, I was off by about 150 rpm or so. After moving the throttle a couple of times it locked up eventually, worked fine the rest of the day. Seems to work 50% of the time like it is supposed to, the other half it refuses to lock up, either in overdrive or in 3rd with the O/D off. The only other thing I have noticed is that the transmission shift kinda smoother. It always has been a little harsh between 2-3 and 3-4, but lately it shifted smooth as can be, I figured I had her finally broke in!

Anyway, any idea's on what could cause this?

Thanks in advance

Pete

 

[VolsFan]

On my auto 99 ( which I just sold) I had the same issue, noticed esp. under load. I grounded the APPS wire, no. 14 i think? has a green stripe on it, grounded it to the neg terminal on drivers side battery and cured my symptoms, i got it from instructions from suncoast. I did this after i had my trans built too, I was annoyed when it happened but realized it wasnt the trans shops fault. Also did it on my dads 99 and he has put some hard miles on that thing, well over 400k and its working fine,truck doesnt look pretty though

 

[PVanderlugt]

I will look at that, I have a noise filter on the Apps wiring and the problem is not the common locking/ unlocking of the converter, half the time it simply refuses to lock at all. Seems like once it decides to lock, it will work normal from then on. I think I have a new Apps laying around, might install that.
Pete

 

[PetesonM]

Any follow up on this? sounds like the issue mine started yesterday. Thanks

 

[PVanderlugt]

Well, not really, it kinda seems to have fixed itself, 90 % of the time it shifts like it is supposed to, the other 10 % the TQ does not lock up on its own, however if I back-off on the pedal it does lock up. Since it is kinda working I have not messed with it anymore. I have a feeling it is electric in nature, since OD and lock up are controlled by the computer, but it weird how all shifts, including 1-2 and 2-3 are much smoother now then before. OD and lock up used to be pretty harsh but is now smooth as can be. What I don't know and not even sure it is possible, that when the TQ does not lock , and I play with the throttle to get it to lock , the rpm drop is only 100 rpm or so, almost like the TQ was partially locked? If that is even possible? If anyone has anymore suggestion I am listening
One of these days I M going to bolt in a G56, and be done with it.
Pete

 

[Joe Mc]

What does the team at Goerend say? You should give them a call, we all paid enough to have our trans build right regardless of who we chose to do the job, this amount paid should allow us a little free over the phone advise/troubleshooting. It could be something as simple as a transducer or other electronic thingy-ma-bob... .

 

[PVanderlugt]

Yeah, I need to give Dave a call and see what he thinks.
Pete

 

[Axtell3]

You may need to adjust the TV cable. or check that the lever is able to move freely on the transmission itself. Mud, salt, cold etc could affect it.

 

[PVanderlugt]

I did look at the TV cable, and everything looks to be moving free and smooth, with no slop. I will double check next time it goes on the lift
Pete

 

[cerberusiam]

The TV cable won't effect lockup, thats computer control based on the parameters from the output shaft speed sensor, gov pressure, and APPS. If working the throttle causes it to lockup you likely have an APPS that is marginal or a bad connection somewhere.

If your curious about the shifting and lockup, you might want to run the pressure test on it and see if they look good.

A temp fix would be a mystery switch to lock the TC manually. That will at least tell you if it is electornic or ther is a problem with the lockup solenoid.

 

[Hitec.Redneck]

I had a problem with my 02, when I hit a rough spot of highway or some bumps the truck would shift out of overdrive. After doing a lot of research the lockup and overdrive are both controlled by solenoids. There is an electrical connection on the top of the transmission where the overdrive switch and the PCM connect to the transmission, mine was loose. I disconnected it, cleaned the connection with some contact spray, reconnected it and have not had any of these issues again. I guess over time the connection became loose from all the bouncing. You may want to check yours.

 

[blasterfdc]

Hey Guys, researching my issue and came along this post. I don't see a fix here. I'm having a very similar issue. Just had my trans build by a local shop, a lot of upgrades. My original issue was shuttering, especially while towing. When he opened up the torque converter the clutch was purnt to a crisp and a few of the higher clutches in the trans were showing excessive heat. Now that everything is back together, it doesn't lock up unless you play with the gas. Putting a reader on the computer it shows the computer sending the signal. He's still troubleshooting but is really at a loss. He's looking at going back into the valve body again to see if something is wrong. any sugestions.

 

[cerberusiam]

Did he replace the solenoids and VB harness? A switch tapped to the OD sense circuit will tell you if it is mechanical or electrical and at least indicate a direction to go.

 

[blasterfdc]

I know the solenoids were repaplaced, I don't know about the VB harness but wouldn't think so.

 

[cerberusiam]

Normally it is easier to do the harness and solenoids as 1 piece, the OD and TC lockup ones that is. The plug and the whole harness deteriorates over time and replacement solves a lot of problems. Same with the transducer and gov solenoid. Hopefully with a rebuild all that stuff is new.