Kevinflys Posted October 14, 2021 Share Posted October 14, 2021 (edited) Hi guys, My 1990 TC lives a pretty easy life spending most of it's time covered waiting for another sunny day joy ride. Lately the joy ride is revealing a transmission shift problem. I've looked in the forum threads and have not seen this particular issue so maybe someone can share some insights. When coming to a stop I sometimes get a clunk - but the main issue is that the transmission is not shifting into top gear so rpms are staying high at highway speeds....until...I tap the brake pedal. Than it upshifts and the torque converter smoothly locks. If I tap it again... downshift and high rpms again. I'm not familiar with the electronic controls of this transmission but does this sound familiar to anyone? I downloaded an A604 overhaul manual and didn't see anything in the troubleshooting to help with this particular item. Shifts are smooth and crisp other than these two strange issues. I'm puzzled. Thanks in advance for the cumulative wisdom sharing! Kevin Edited October 14, 2021 by Kevinflys (see edit history) Link to comment Share on other sites More sharing options...
Hemi Dude Posted October 14, 2021 Share Posted October 14, 2021 Have you had the transmission controller replaced lately? If so, there is an easy fix for your question? Send me a message through the PM process here. Thank for your question. Link to comment Share on other sites More sharing options...
Ronnie Posted October 14, 2021 Share Posted October 14, 2021 3 hours ago, Kevinflys said: the main issue is that the transmission is not shifting into top gear so rpms are staying high at highway speeds....until...I tap the brake pedal. Than it upshifts and the torque converter smoothly locks. If I tap it again... downshift and high rpms again. Could it be the switch on the brake pedal that tells the ECM you have your foot on the brake is going bad? Maybe when you tap the brake you are getting the contacts in the switch to close until you tap the brake again. If you had a GM car I would almost bet that is the case but your TC might work differently. Link to comment Share on other sites More sharing options...
Hemi Dude Posted October 14, 2021 Share Posted October 14, 2021 This is a common condition that occurs when the TRANSAXLE CONTROLLER has been replaced with an UPGRADED one. The replacement controller itself is accompanied with instructions that tell you what to do if this occurs. It is a matter of 'CUTTING' and taping back the #49 conductor (wire) under the cover of the 60 way connector at the transaxle controller. Link to comment Share on other sites More sharing options...
Kevinflys Posted April 22, 2023 Author Share Posted April 22, 2023 (edited) I know it's been awhile since I asked this question. The TC has been in the barn waiting for better weather - before that it spent months getting the smoke screen issue cured with replacment cylinderheads.... so finally I'm ready to cut the number 49 wire in the 60 wire connector but where is it? I see something that looks like a control module on the front right fender near the air conditioner hoses. Potentially another one on the left hand side. Thank you for the help! Edited April 22, 2023 by Kevinflys (see edit history) Link to comment Share on other sites More sharing options...
Kevinflys Posted April 22, 2023 Author Share Posted April 22, 2023 (edited) OK, I found th answer to the location on another post - it was the one on the right fender. For anyone who comes along later this is the simple fix Hemi led me to. Disconnected the battery, unbolted the central bolt holding the connector in place and did not find any numbers on the terminals. Opened the cover on the harness connector and ahhhh there are the numbers! Located number 49 - a white with pinkish stripe wire on my '90 model. Then fighting my internal resistance to ever intentionally cut a factory wiring harness I snipped that rascal. Taped it up, closed the harness cover and reinstalled the plug. Reconnected the battery and went for a test drive. Perfection! Thank you Hemi! The car has never shifter so well. Edited April 22, 2023 by Kevinflys (see edit history) Link to comment Share on other sites More sharing options...
mensanguy Posted April 22, 2023 Share Posted April 22, 2023 (edited) What are we ever going to do when Hemi is no longer with us???! It will be a sad day indeed........ Edited April 22, 2023 by mensanguy (see edit history) Link to comment Share on other sites More sharing options...
Hemi Dude Posted April 23, 2023 Share Posted April 23, 2023 4 hours ago, mensanguy said: What are we ever going to do when Hemi is no longer with us???! It will be a sad day indeed........ You guys will just have to rely on all the information Bob French is gathering in his library of 'TCA Owners Club Information." 1 Link to comment Share on other sites More sharing options...
Garnet & Gold Posted April 23, 2023 Share Posted April 23, 2023 I'm right behind you at 80 years of age. But I don't look it. Link to comment Share on other sites More sharing options...
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