resolved (probably?): had a bad transistor on the ECU and a bad capacitor on the TCU. gonna replace.


Today when starting my car the D4 light stayed on after ignition no matter which gear I was in. Shifted and drove in reverse fine, as well as D1, however D2-D4 gave very little power. Did some Googling from my phone, tried to get some insight.

The first thing I did was simply remove the negative terminal, wait a minute and throw it back on. Turned my car to II and both the CEL and D4 lights came on, however after a few seconds they both shut off. Proceeded to start my car and drive home perfectly fine, no problems at all.

Once I got home, did some research online. Went back out to my car about 20 minutes later, turned it on, and the D4 light stayed illuminated once again. Decided to once again do the battery trick, which worked, however when I turned my key to III it tried to start for about a second, and then all electronics shut off (except interior light) shut off. This has happened before, about 5 times in the past year. Every time this happens no electronics will work at all until I remove the negative terminal for a few seconds and put it back on. Then, every time so far I can start the car perfectly fine afterwards.

Tried to read the CEL code. With the wire jumped and key turned to II, the D4 light does not come on at all, and the CEL light comes on and stays illuminated. No blinking at all. As soon as I pull the jumper wire out and turn the key to II, it goes back to the CEL + D4 light turning on for a few seconds then turning off. Car continues to operate fine. Repeated this a few times, same result every time. I have not yet tried to reset the ECU by pulling the fuses and negative terminal for 15 minutes cause it's been raining since I got to investigate (thanks hurricane Matthew). Will try this first thing tomorrow and see what happens.

Also, possibly unrelated but figure I'll throw it in: a couple weeks ago as I was driving all of my dashboard lights and headlights went out. I tried turning the switch back and forth a few times to no avail. After about 10-15 seconds, they all came back on. This could be related to the problem I was describing before?


Any idea what could be happening? All I can really pinpoint myself at this point is something with the electronics somewhere is messed up. Whether it's a bad ECU, TCM, or connection somewhere? I have no idea.

Thanks for your time reading this, a little long, but tried to include all the details and steps I've already taken.


edit: could this have anything to do with it? or at least the issues with starting the car to have everything shut off? http://techauto.awardspace.com/ignitionswitch.html

edit 2: found a thread on another site indicating that on startup the CEL and D4 are supposed to turn on for a brief second before turning off. looked up some youtube videos of 92s being started and some of them seem to have that and others dont. i've never noticed the D4 turning on before, but definitely the CEL always has. maybe I just haven't noticed it? i don't know anything anymore.

 

I would suspect the ignition switch, use the techauto link to diagnose/inspect/replace it.
Also check that the memory fuse for the ECU is good, without it the ECU/TCU will not retain memory of codes.
You can also check for codes with the engine running, it is not ideal, but if the memory is not working this may be your only option to capture the codes until the other problems are resolved.