Help troubleshoot tranny TCC issue
Thread Starter
Heel & Toe
Joined: Dec 2015
Posts: 16
Likes: 1
From: Fort Saskatchewan Alberta
Help troubleshoot tranny TCC issue
I have a 1987 with an automatic transmission. What I have noticed is the tranny is jumping back and forth in/out of overdrive when I'm at highway speeds. Pressing and holding the break while at speed keeps it from shifting up or disables the TCC from locking up. It will also jump around if it is cruise control.
I have done the test with a "test light" where it is connected from ALDL terminal "F" to ground and the light is "on" and the TCC solenoid is disengaged. I also raised it on my lift and ran it up to 70 mph with test light still hooked up to terminal "F". I noticed that the light would stay "on" up to about 45 mph then when it would lockup the light would be "off" which makes sense because it is locked-up but then the test light would randomly blink on/off. All while I'm holding the speed steady. What do I check for now? I do not have a scan tool, only a test light. Any tricks or tips is appreciated. THX
I also swapped the PROM back to the factory one to see if anything would change and it reacts exactly the same.
I have done the test with a "test light" where it is connected from ALDL terminal "F" to ground and the light is "on" and the TCC solenoid is disengaged. I also raised it on my lift and ran it up to 70 mph with test light still hooked up to terminal "F". I noticed that the light would stay "on" up to about 45 mph then when it would lockup the light would be "off" which makes sense because it is locked-up but then the test light would randomly blink on/off. All while I'm holding the speed steady. What do I check for now? I do not have a scan tool, only a test light. Any tricks or tips is appreciated. THX
I also swapped the PROM back to the factory one to see if anything would change and it reacts exactly the same.
Last edited by sirmike68; Nov 29, 2017 at 05:21 PM.
Team Owner
Joined: Jul 2004
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From: Hartford WI
Thread Starter
Heel & Toe
Joined: Dec 2015
Posts: 16
Likes: 1
From: Fort Saskatchewan Alberta
Also while running the car on the lift i tried to engage the cruise control. When i did the car reved right up then backed right off just like as if i was pumping the gas until inturned it off. It does control nicely while on the road, maybe being on the lift free wheeling is not something its setup for.
Last edited by sirmike68; Nov 29, 2017 at 11:07 PM.
Thread Starter
Heel & Toe
Joined: Dec 2015
Posts: 16
Likes: 1
From: Fort Saskatchewan Alberta
I have not done anything with the TV cable.
Also while running the car on the lift i tried to engage the cruise control. When i did the car reved right up then backed right off just like as if i was pumping the gas until inturned it off. It does control nicely while on the road, maybe being on the lift free wheeling is not something its setup for.
Also while running the car on the lift i tried to engage the cruise control. When i did the car reved right up then backed right off just like as if i was pumping the gas until inturned it off. It does control nicely while on the road, maybe being on the lift free wheeling is not something its setup for.
Last edited by sirmike68; Nov 30, 2017 at 11:53 AM.
Thread Starter
Heel & Toe
Joined: Dec 2015
Posts: 16
Likes: 1
From: Fort Saskatchewan Alberta
Thanks for the replies. Since I already have the TV cable ordered and it is kinked up I'll change it out. I don't have access to a scanner and driving the car in the snow is not an option. Ha! So I'll start looking into VSS, MAF, and TPS and wiring.
Safety Car
Joined: Aug 2009
Posts: 3,752
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From: Melbourne, Victoria, Australia
(An added benefit of any Power Chip is there-programming of torque converter lock-up. Power Chip delays the lock-up until high gear which significantly improves driveability.)
https://www.corvettecentral.com/c4-8...m%26count%3d72
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Thread Starter
Heel & Toe
Joined: Dec 2015
Posts: 16
Likes: 1
From: Fort Saskatchewan Alberta
Update now that its summer and I can finally drive around I believe I have found my problem. I bought a scan tool this winter and ran the car on the hoist for a while collecting some data. I could see the TCC lockup signal engage/disengage as it should so everything electrically seamed normal. The next test I did was to pull the electrical connector for the TCC off the tranny and go for a drive. Low and behold with the TCC wiring unhooked everything ran smooth as silk all the way through the gears. Now I think I can safely assume that the issue is with the TCC solenoid and that I should replace it.
