Monkey Boy 1 Posted July 1, 2023 Report Share Posted July 1, 2023 Looks as if my ECM/TCM unit is playing up on my Gen6 vert auto. I am trying to find recommendations for any companies who members have used for diagnostic/repairs to these units. More and more I am hearing about breakdowns in solder connections or capacitors going bad on these units, so any advice, recommendations would be greatly received Problem is that the car virtually misses out 3rd gear when changing up through the gears and goes straight to 4th Overdrive. Will not kick down when accelerating. Had the fluid changed twice and both solenoids changed but still have the issue. As these cars are pretty uncommon, hardly anyone has any info or background on them and parts are hard to track down for the 3S-GE/A140E powertrain. Link to comment Share on other sites More sharing options...
_Chris_ Posted July 1, 2023 Report Share Posted July 1, 2023 I believe Paul (Paulus) up in your direction has a contact that will replace ECU capacitors and repair tracks damaged by the leakage but not sure whether he has test gear, I certainly don't. I'm not sure whether the engine ECU also controls the gearbox or whether there's a separate control. Worth doing some research. When I was looking into my auto box that went erratic, it looked more like it was a traditional auto box with mechanical/hydraulic control modified by solenoids. In my case the problem was solved by another 'box rather than electronics. Link to comment Share on other sites More sharing options...
Monkey Boy 1 Posted July 3, 2023 Author Report Share Posted July 3, 2023 I have changed both solenoids in the box but to no avail, so my last resort is the ECM/TCM to be repaired / changed. Finding one is like looking for the Unicorn of all unicorns. The unit controls both engine & gearbox, hence the A140E designation. So repair seems to be the next best option. (unless someone out there is breaking a JDM Vert Auto.) Link to comment Share on other sites More sharing options...
paulgtt Posted July 13, 2023 Report Share Posted July 13, 2023 Iv used these before for repairs to ABS modules, might be worth a shot https://www.ecutesting.com Link to comment Share on other sites More sharing options...
Monkey Boy 1 Posted July 26, 2023 Author Report Share Posted July 26, 2023 Well, the latest update is that I had a look at the inner workings of the ECM/TCM. Two of the capacitors had failed, (leaking out over the circuit boards). one of them actually fell off the PCB as it was so corroded. It looked as if it had also wrecked come of the circuit tracking, I cleaned up all that I could, put it back on the car to make sure it still fired up, which it did., and then took the car for a spin to see what would happen. Very surprised that the car now seems to work perfectly, changing gears where it should, kicking down a gear or two depending on acceleration & speed. It even worked perfectly on a 400 mile round trip from Norfolk to Hampshire for Simply Japanese show. I have purchased some replacement capacitors (25p each) 50v 10uF which I will probably solder in place over the next month or so when the car is coming off the road for a bit more suspension work. So watch this space . 3 Link to comment Share on other sites More sharing options...
_Chris_ Posted July 26, 2023 Report Share Posted July 26, 2023 In case you don't realise, make sure they go the right way round, assuming you've bought electorlytics like the originals. The gunk is conductive as well as corrosive, and it's possible that was causing the issues rather than broken tracks. If it's thoroughly cleaned with a solvent such as IPA or thinners then it's worth sparing with laquer, or preferably cobformal coating (HPA or APL). 1 Link to comment Share on other sites More sharing options...
Monkey Boy 1 Posted July 26, 2023 Author Report Share Posted July 26, 2023 Couldn't upload the photos earlier due to poor signal coverage at work. This is the circuitry on the ECM/TCM module. and you can see the brown gunk coming from the capacitor. Yes, I am fully aware that the capacitors only go on one way. 1 Link to comment Share on other sites More sharing options...
slybunda Posted September 12, 2023 Report Share Posted September 12, 2023 Nasty capacitors. Can you change for polymer ones and be done with it for life? Im wondering if i should take out my gen7 ecu and check its caps too to be on the safe side Link to comment Share on other sites More sharing options...
_Chris_ Posted September 13, 2023 Report Share Posted September 13, 2023 I don't think polymer give a massive longer lifespan especially at higher temperatures. They do tend to have a lower ESR which may be a benefit for some, especially the 10uF which are usually the first to go and I suspect the reason being high ripple current as they don't have a paralell ceramic capacitor. For smaller values like the 10uF, ceramic capacitors are now available in a usable size and should offer much longer lifespan and lower ESR. I have had a report that these caused a problem in an ECU though I've used them in others with no issue. In theory, tantalum should offer a better lifespan for the larger values however they are much less robust as far as over-voltage surges and explode when subjected to them. On newer exu's, be aware that gen6 uses a 4 layer PCB and the inner power planes appear not to have thermal breaks. This makes it much harder to melt solder all the way through to remove / refit components and damage to the through plating cannot easily be repaired with links as the tracks are impossible to trace. This means there is a finite risk to changing the capacitors which could desroy an otherwise perfectly working ECU. I would be surprised if the gen7 ECU wasn't also a 4+ layer PCB. 1 Link to comment Share on other sites More sharing options...
slybunda Posted November 2, 2023 Report Share Posted November 2, 2023 I need to get a move on with this and for curiosity sake take the ecu out of my gen7 and take the lid off to check its condition. Car is 23 years old now and its around this time caps start to give up. Got to catch them before they leak. Anyone with a gen7 checked the ecu yet? Link to comment Share on other sites More sharing options...
ams Posted November 3, 2023 Report Share Posted November 3, 2023 only issue ive seen on the gen7 ecus is the immobiliser part and keys no longer matching , not looked at root cause Link to comment Share on other sites More sharing options...
_Chris_ Posted November 3, 2023 Report Share Posted November 3, 2023 I'd be interested to see the inside of a G7 ECU if someone can post up piccies. I'm expecting fewer electrolytics, modern designs tend to use far less. Link to comment Share on other sites More sharing options...
slybunda Posted November 3, 2023 Report Share Posted November 3, 2023 will get mine removed and take some pics at some point. too much rain these days Link to comment Share on other sites More sharing options...
Xanadu Posted November 4, 2023 Report Share Posted November 4, 2023 10 hours ago, _Chris_ said: I'd be interested to see the inside of a G7 ECU... I found one photo from Celica Hobby (2ZZ-GE) Link to comment Share on other sites More sharing options...
_Chris_ Posted November 4, 2023 Report Share Posted November 4, 2023 Interesting. Looks like it's a single PCB rather than the split PCB of the previous generations. Presumably possible due to the change to entirely surface mount. I can see 3 electrolytics at the top, 2 of which are in paralell and also in paralell with what looks like a 10uF ceramic so I would guess resevoir capacitors on a supply rail. The earlier ones didn't have the paralell ceramic on the 10uF capacitors which I suspect is the reason these were the first to fail. The 2 main things that kill electrolytics are heat and high frequency ripple. There are also a couple just visible at the bottom but unable to see any tracks that might indicate their function. Link to comment Share on other sites More sharing options...
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