One day my check engine light and trac off light came on. Its never came on before on me. Well I continued driving it and the light went off. I didnt see if for a couple of days but it came back on and off every once in a while. Well It now comes on every time I start the car and slowly dims out and the trac off light just pops off when it starts to dim. Well I checked codes. 21 28 and 41 came up. SO I figured it was the TPS causing this weird light problem. Cause the light will vary with brightness with the throttle but only while its in gear, not in park or neutral. So bought new toyota tps, installed adjusted. All is good but Check engine light is still on. Only codes left are 21 and 28. I do not understand why the check eng light would vary with throttle with Oxygen sensor codes only.
Guess I will buy new upstream o2s and hope the light and code problem goes away. But for some reason im doubting it will.

 

There's no load on the engine free revving or at idle, but there is when driving. Possible you're having charging issues too. Only reason I can think of that a light gets brighter with throttle.

The way the check engine light works is that power is supplied to the light, and fed into the ecu. When there's a problem, the ecu provides a ground. So yeah, unless your ecu is going bad which is quite possible too, I'd also go through things that'll effect charging along with figuring out the o2 stuff.

 

ecu sounds suspect, I would open it up and take a look.

 

well I ordered 2 new upstream denso oxygen sensors. I hope that fixes it. If not I will take a look at the ecu and figure out if theres any broken solder joints and any obvious damage. Any idea where to look inside the ecu? I know I had a hard time retrieving codes.

 

You would be looking for leaking capacitors and any other obvious damage.

 

I can't remember where I read it (maybe the owner's manual?), but I think the CE and Track Off together indicates a limp mode, and needs to be addressed quickly.

 

It takes 10 minutes and zero dollars to look at an ecu. How are you gonna feel if the primary o2s don't do anything? To play devils advocate, the fact that replacing the tps eliminated the tps code is a good sign. What do you mean you had trouble retrieving codes?

 

Well your right it ended up being the ECU. I pulled it apart and found 6 leaking capacitors. 2 Of those 6 destroyed other circuits by corroding them. after replacing them and fixing the bad circuits the engine light and trac light have not came back on. Thanks for the help.