Several weeks ago my 1992 sc300 (175k) shut off on me while driving. I had it towed to my mechanic and it started and ran fine for him. He drove it over the weekend trying to duplicate the problem to no avail. It showed no codes. I got it back and a week later the same thing happened. The mechanic consulted a friend who works at a lexus dealer service dept and was told it was most likely the fuel pump ecu or main engine ecu. I purchased a used fuel pump ecu from a member of this board who was parting out his car and installed it. The car ran fine with this new part, but a couple of days later the battery light came on and at first flickered a bit, but then stayed on. I had the alt rebuilt (some oil from the distributor O-ring leaking had damaged it). I drove it a couple of days hoping that had been the problem all along. Yesterday I was stopped at a traffic light and it shut off, but started right back up and drove fine. I am left thinking I might try the main engine ecu. Is it located under the driver's seat and is it a do it yourself install? Any other ideas on what might cause this. I will drive it again and see if it dies again before I purchase a used ecu. BTW, I have searched the threads and see that the fuel pump ecu is usually the culprit, but probably not in my case. More time will tell. Yesterday's cut off might have been a fluke. Thoughts?

 

Yes, pull up the carpet and disconnect the old ECU and put the new one in. 10 minute job max.

I would do a little more research before replacing the ECU.

Jonny

 

where is the engine ecu located? Sounds like the passenger foot area, but some say under the passenger seat???

 

Those people are wrong. It is in the passenger foot area - right where your foot would be if you were sitting down. Same place your ABS ECU is.

Jonny

 

thanks Jonny,
I am driving and waiting to see if it still cuts off on me and then I will try the main engine ecu. One more question about location. Is it on the side by the right foot or side by the left foot or the back where the soles of your shoes rest? If I'm going to be digging up carpet I'd like to have a clear idea of location. I'm keeping my fingers crossed that the fuel pump ecu I put in is the fix, but I want to be prepared just in case. Thanks again.
Daniel

 

Daniel,

It is somewhat centered on the back of it. There is the ABS ECU and the main ECU. You will know the difference as the one with ABS will say that in large letters. When you pull up the carpet it will be ver clear as to what you are looking for.

Jonny