Yes TCU capacitors are prone to failure. As well as in tach, digital climate control and electronic controlled suspension unit.
If siliconed spot is just forward of dipstick, that would be were the four TCU solenoid wires enter transmission. If any of those wires are broke or shorted to ground you’d have a bigger problem. So I suspect TCU is most likely with other possibilities being pulse generators, even less likely vehicle speed or TPS input.
Oh joy. Thankfully no ECS and our climate controls are a little different. Not sure on that. I'd have to dig it out of the dash when I eventually upgrade the stereo this spring.
Where are these pulse generators? I see people talking about them, but can't find their location.
The only gear that really gives me a minor issue shifting is the 3-4. If under 15% throttle or so, the shift is VAGUE and jumps a little. It acts like it's in final gear and starts to slip down to a lower RPM, but then bangs it into the next gear. Not harsh, just a minor jolt. I'll try to capture it. I usually just go a little harder into the throttle in third gear and it shifts normally.
Here are the pictures I grabbed this evening.
I've been staring at some witness marks on the TPS where someone had taken it off before.
I agree with
@white93gt about pulling the TCU and doing at least a visual inspection of the circuit board, the capacitors, and for other burned/melted components. If you haven't set your TPS since you bought the car, you need to do that next as it can cause your exact symptoms....be sure to use the 0.025" feeler gauge spacer when setting it.
IIRC your car has a traction control system that we don't have. Your ECU is different and has the traction controller (TC) incorporated inside the ECU on a large second circuit board that communicates back/forth only through the ECU board. To complicate it further, IIRC the car has ? wheel speed sensor issues that required you to disable the whole TC system and ABS system, their fuses, ?connectors, ?vacuum lines, ?TC vacuum control solenoid and TC vacuum valve itself. In your first vid. there was ongoing screeching and ticking from one of those units and solenoids, and you are still getting code 71(TC related). I am completely lost on how the TC,TCU, ECU, and ABS inter-communicate. Normally at start-up the ECU quickly does a quick activation of the solenoids, motors, actuators in these systems to confirm their function for safety. I don't know what kind of safety adjustments occur when they detect problems. I do know that other make/models with similar TC systems, change the tranny shifting RPM points in response to such faults....like putting tranny into "granda-mode" instead of full 3rd gear only limp mode we know about when the TCU detects specific faults. If you get good info and get it sorted out, teach us. Sorting out and fixing a wheel speed sensor would be a lot easier and safer than a can of computer worms???
After driving it and before turning the key off, try grounding OBD pin 6 to CEL blink out any pending tranny codes....same as you have been doing on pin 1 to get the 62 and 71 codes.
The trans fluid is 5 years old and around 20K, but looks and smells good.
I am unsure of the ECU differences as well. We are going on a trip late February to visit some family, so I'm hoping to send off the ECU/TCU get them recapped to be safe. I may grab a $30 TCU off eBay just to try that before $250+ computer repairs.
I'll have to look into the TPS proper setting. I knew that came into the calculations.
The ABS system was disabled by the previous owner. He had a brake/ABS light show up on the dash. The shop replaced the wheel sensor but the light persisted. They checked all other sensors with a voltmeter, but couldn't find a fault. I assume the owner declined any further diagnosis/work, as unplugging the ABS box disables the system, so no more light on the dash
The CEL codes are quite rare. They never show up on a cold start. Only when fully warm and short stops. So if I drive for 15 minutes, hop out for 2-3 minutes, and back in the car, the CEL will come on after 30 seconds. This only happens perhaps 2-3x per month. Half the time, it goes back out a few minutes later. It's very strange.
Might it be worth a shot to plug in the ABS module and see what happens? A replacement is only $20 on eBay, so I might give that a try. That noise is the ABS pump behind the headlight. It makes a mild grinding noise that sounds extremely similar to a starter not disengaging. Like you say, the ECU may be trying to prime the pump via the ECU's TCL controller.
I found a 3000gt mechanic nearby that I'm going to have pressure/smoke test for vacuum leaks. If he feels like he can take on something like this, it may be worthwhile. There is also a reputable vehicle electronics shop that my family has known for 20+ years. He might be a good resource for electrical oddities in the systems.
I'm doing the plugs and wires in ~10 days just to be sure that's not causing my very minor power loss and misfire. I dropped one of the plugs when inspecting the car and caved in the ground electrode. Perhaps I damaged the ceramic core or electrode?? I regapped it to .43 so it seemed fine. With that done and the pressure test passed, I'll probably live with it for the next 50K til the TB is due again.
There are 2 OBD style connectors down there. I'll try to find the proper pin tomorrow and report back.
PS Moths, the forum has taken away my ability to like your posts. Guess I gotta spread the love around some more before I can give you another.
I just saw that mentioned in another old post from like '09 as well. Any other modules that have crappy capacitors?
