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That is cray-cray. Funny, my C622 puked its guts out, as well. If we had the schematics, troubleshooting broken tracers and pads would be a breeze. I don't see too many OEM ECUs on the market, so keeping mine was important to me for the auto transmission. If not, I was going to bite the bullet and switch to a ProEFI and not look back. I still may switch soon... who knows. I change my mind daily. I've been BPU since 2001, so maybe it's time to unleash the beast.
 

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Stock Twins King
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Discussion Starter #22
Well after installing a new ECU and that still didn't eliminate the ODO issue I went and bought a new Trac ECU. That fixed the issue I think. I will install on Monday but from the diagnostics it shows that this ECU is bad because it is not outputting 12v to properly drive the ODO circuits.
 

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Wow, dude. That sucks. But glad the Trac ECU may have fixed the issue. Who knows what other issues those bad caps were causing.

I have less than 30 miles on my new ECU capacitors, but if my "TRAC" codes reappear any time soon, I will be looking for a new Trac ECU... or standalone that can control the auto transmission.
 

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Stock Twins King
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Discussion Starter #24
Final update. As it turned out I had both Throttle and Main ECU bad. I bought 3 used Throttle ECUs which fixed one issue. Today I got another main ECU and now all is FINALLY working. So 2 of the main ECUs I bought used were Bunk as well as my original one. Quite costly solving this issue. More bummed as I did go into all these bunk ECUs and replaced all the Caps as well which didn't fix anything. The new GOOD one I got today was actually the earlier 93 version 89661-14490
 

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My cruise control issues, O/D code 89, false code 24 and TRAC OFF, and MANU OFF all started about the same time. Many systems, you know, (VSS, TRAC, throttle pos sensor) talk to each other in the ECM with "system logic". All my issues were remedied by the new capacitators. I thought it was odd. I wondered about the signal shaping that actually takes place in the odometer circuitry... and why is the uncorrected signal (spliced VSS) still clean enough to feed information to the ECM.

Yes, I have had solder-joint issues with my speedo in the past. I fixed some of the larger, more visible solder breaks many years ago. You are correct about the breaks in the tracers tiny tracers. I have squirrel hands, but not ant hands!!!!
Hi,
I actually have the exact opposite problem my manual mode won’t deactivate. Do you have any idea what could be wrong?
 

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Hey, 808.
Is your transmission actually stuck in MANU mode? or is the auto-mode still working? Do all gears shift normally? Have you done ANY ecu wiring harness modifications? Any other issues with your dashboard gauges/dash lights? (i.e. dim "!" warning light, TRAC illuminated, cruise control not engaging, etc.???)

There are full A340E service manuals online with detailed trouble-shooting procedures, but off the top of my mind, a couple things I would try: 1) check for any transmission ECU trouble codes, 2) check your MANU button and harness/clips, etc. You'll have to remove the console trim panels to inspect. the contacts inside the MANU button may be corroded or burned. It is a "momentary switch", so you could use a small jumper to bypass the switch and trigger the ECU to see if it's a switch problem. 3) the crux of our 25+ year-old ECU problems... inspect the ECU for leaking capacitors.
 

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Hey, 808.
Is your transmission actually stuck in MANU mode? or is the auto-mode still working? Do all gears shift normally? Have you done ANY ecu wiring harness modifications? Any other issues with your dashboard gauges/dash lights? (i.e. dim "!" warning light, TRAC illuminated, cruise control not engaging, etc.???)

There are full A340E service manuals online with detailed trouble-shooting procedures, but off the top of my mind, a couple things I would try: 1) check for any transmission ECU trouble codes, 2) check your MANU button and harness/clips, etc. You'll have to remove the console trim panels to inspect. the contacts inside the MANU button may be corroded or burned. It is a "momentary switch", so you could use a small jumper to bypass the switch and trigger the ECU to see if it's a switch problem. 3) the crux of our 25+ year-old ECU problems... inspect the ECU for leaking capacitors.
Hi,
When I start the car (in P) the Manu light is already on without me even pressing the switch. The D light on the dash won’t illuminate just the manu light indicator which won’t turn off even by pressing the switch. It shifts manually but when in “D” seems like it’s stuck in second or third??..Just tested cruise control for the first time and I believe it’s working. The cruise light is supposed to stay on correct, When in cruise mode that is? But no other lights like you mentioned but I do have the occasional O/D light flashing but very intermittent. I will check the manuals and see if my mechanic can get some codes. Thanks for your input really appreciate it.
 

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Sounds like your car IS stuck in MANU mode. Shifter in "D" position = 3rd gear when in MANU. Not sure why "D" is not illuminated in dash when shifter is in "D". Could be a burned out "D" lamp bulb in the dash. Does L,2,N,R illuminate in the dash with the appropriate shifter position?

Yes, "CRUISE" will be illuminated, but you need to see if actually works and holds the desired speed. If it doesn't, it could be the VSS signal and you'll need to do some soldering, buy a new odometer cluster, or just do the pink wire jumper modification on the odometer wiring harness.

You don't need a mechanic to check the tranny codes! You can get the transmission codes when getting the CEL codes. Read the blinks, just like the engine CEL codes.

Sounds like a fun mystery! If total irrational, unexplainably weird issues continue, I'd bet you have a several leaking capacitors in your ECU. If that is the case, you can try to replace all the capacitors, find another auto ECU, or take the leap to a stand-alone!!! :)

Good luck!
 

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Sounds like your car IS stuck in MANU mode. Shifter in "D" position = 3rd gear when in MANU. Not sure why "D" is not illuminated in dash when shifter is in "D". Could be a burned out "D" lamp bulb in the dash. Does L,2,N,R illuminate in the dash with the appropriate shifter position?

Yes, "CRUISE" will be illuminated, but you need to see if actually works and holds the desired speed. If it doesn't, it could be the VSS signal and you'll need to do some soldering, buy a new odometer cluster, or just do the pink wire jumper modification on the odometer wiring harness.

You don't need a mechanic to check the tranny codes! You can get the transmission codes when getting the CEL codes. Read the blinks, just like the engine CEL codes.

Sounds like a fun mystery! If total irrational, unexplainably weird issues continue, I'd bet you have a several leaking capacitors in your ECU. If that is the case, you can try to replace all the capacitors, find another auto ECU, or take the leap to a stand-alone!!! :)

Good luck!
Yes the cruise holds speed and all the other gears are illuminated. Haha fun mystery is being optimistic. Thanks for the input bro gonna try to read the codes myself.
 

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Final update. As it turned out I had both Throttle and Main ECU bad. I bought 3 used Throttle ECUs which fixed one issue. Today I got another main ECU and now all is FINALLY working. So 2 of the main ECUs I bought used were Bunk as well as my original one. Quite costly solving this issue. More bummed as I did go into all these bunk ECUs and replaced all the Caps as well which didn't fix anything. The new GOOD one I got today was actually the earlier 93 version 89661-14490
HI Stu,
You wouldnt happen to know the Part number for the throttle ecu would you? If possible for 94 tt auto usdm?
 

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Sounds like your car IS stuck in MANU mode. Shifter in "D" position = 3rd gear when in MANU. Not sure why "D" is not illuminated in dash when shifter is in "D". Could be a burned out "D" lamp bulb in the dash. Does L,2,N,R illuminate in the dash with the appropriate shifter position?

Yes, "CRUISE" will be illuminated, but you need to see if actually works and holds the desired speed. If it doesn't, it could be the VSS signal and you'll need to do some soldering, buy a new odometer cluster, or just do the pink wire jumper modification on the odometer wiring harness.

You don't need a mechanic to check the tranny codes! You can get the transmission codes when getting the CEL codes. Read the blinks, just like the engine CEL codes.

Sounds like a fun mystery! If total irrational, unexplainably weird issues continue, I'd bet you have a several leaking capacitors in your ECU. If that is the case, you can try to replace all the capacitors, find another auto ECU, or take the leap to a stand-alone!!! :)

Good luck!
You were exactly right! New ECU solved everything! Thanks a bunch!
 
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