Burnt TCU Check it out

[JBDdsmer610]

Alright so i been trying to put this 91 AWD on the road for a while i had to park it for a bit because i got in some trouble. but when i first got the car it shifted fine, then when i let it sit i started it up and i smelled something electricle burning. then i drove it and it was in limp mode so i pulled the tcu and heres what i found.......Can this be fixed or should i replace it?

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[GalantGreg]

Had the same problem with my 92 GSt. You definately need another TCU. Take note of your MD number, because that is the only one that will work. As long as you keep your car, do what I did and get an extra one. You need MD750093.

 

[JBDdsmer610]

yea i figured that but i've been searching for a tcu for 2 days and cant find one still need to call a few junk yards

 

[ilco187]

that's the same thing that happened to my 92 awd a/t, i went to a junkyard and asked them if i could take the tcu in the yard and match them up he said sure and marked the case with yellow, i found one and quickly switched the circuit boards out and left.

DSM TCU part numbers
TCMs, TCUs for Eagle Talon

 

[JBDdsmer610]

ok so i replaced the tcu in the car and it still isant shifting all the wires and plugs are fine cant figure this one out. I am throwing a CEL for a knock sensor and it wont clear. Could this be why the car wont shift?

 

[ilco187]

did you disconnect the battery before plugging in the tcu/as for knock sensor no it wont play in the shifting role just detects knock, but replace knk sensor if its not unplugged like mine was when i got my A/T awd

 

[JBDdsmer610]

Yes i disconnected the battery and i replaced the knock sensor and it still throws the code. Idk when i bought the car it shifted fine then i let it sit for a couple months and now it dont shift......time for a 5 speed swap i guess again

 

[ilco187]

TCU Codes (Automatic Transmissions) DSMs

TCU Codes

 

[steve]

Wow, I know that tantalum caps can short but I've never seen one do it.

The leaking electrolytics I see plenty of. The TCU uses the same defective 47uf cap that's in the ECU's so they need to be replaced just like with the ECU or they will die. Unlike the ECUs the odds of the leakage killing the TCU is about 50% based on what I've seen. The damage to C24 can cause the voltage regulator to pump 12v onto the 5v rail and that blows everything else.

 

[JBDdsmer610]

Ok so i used a volt meter to check for tcu codes its not throwing any codes. But i noticed some lose wires on my ecu i took the ecu out and found the o2 sensor wire cliped and hanging. and the knock sensor wire was cut and lopped in with another wire. eigther way im fixing the wires, but do you think this caused my car not to shift?

 

[spawn7037]

that's the same thing that happened to my 92 awd a/t, i went to a junkyard and asked them if i could take the tcu in the yard and match them up he said sure and marked the case with yellow, i found one and quickly switched the circuit boards out and left.

i have a new best friend!

 

[JBDdsmer610]

Dosent help me much

 

[ilco187]

Ok so i used a volt meter to check for tcu codes its not throwing any codes. But i noticed some lose wires on my ecu i took the ecu out and found the o2 sensor wire cliped and hanging. and the knock sensor wire was cut and lopped in with another wire. eigther way im fixing the wires, but do you think this caused my car not to shift?

no those wont have a role in the shifting it could be one of the relays/solenoids went bad also for the trans, check the fuse under the kick panel called (4 A/T)

 

[JBDdsmer610]

yea i pulled that fuse already it was fine i was gonna just try swapping it out and putting a new one in. Well if i cant figure this one out i guess i will do a speed swap in the streets of easton. Everything for the swap is in the trunk so it will be easy.

 

[JBDdsmer610]

OK guys needless to say i found my problem i picked up a new tcu from someone on dsm source well from what he told me the caps were replaced well today i took the liberty of taking the new tcu apart to inspect it. and i found a burnt cap on the bottom of the board. so i already replaced the orange resistor whitch i pulled from my old board and im going to the local dsm shop to pick up a new CAP. ill let you guys kno how it goes.

 

[toofast82]

OK guys needless to say i found my problem i picked up a new tcu from someone on dsm source well from what he told me the caps were replaced well today i took the liberty of taking the new tcu apart to inspect it. and i found a burnt cap on the bottom of the board. so i already replaced the orange resistor whitch i pulled from my old board and im going to the local dsm shop to pick up a new CAP. ill let you guys kno how it goes.

Good luck, hope it works out!

The leaking electrolytics I see plenty of. The TCU uses the same defective 47uf cap that's in the ECU's so they need to be replaced just like with the ECU or they will die. Unlike the ECUs the odds of the leakage killing the TCU is about 50% based on what I've seen. The damage to C24 can cause the voltage regulator to pump 12v onto the 5v rail and that blows everything else.

Thats why Steve gets to play around with my ecu's. He know's too much about this stuff

 

[JBDdsmer610]

well put new CAP's in and resistors pluged everything in and still no GO so im tired of wasting my time and money on this A/T im starting my 5sp swap in the street tomorrow.

 

[ilco187]

i just figured i would throw this link at you for further help on the swap.

Converting a 1G FWD DSM Auto

 

[rich3389]

i just figured i would throw this link at you for further help on the swap.

Converting a 1G FWD DSM Auto

Hhaha he doesnt need that, he has done 5 speed swaps to many dsms's before.

 

[JBDdsmer610]

Yes rich can vouch that i am a veteran at this.