ECU resetting after every shut down!

[Benji]

Since I've been logging my fuel trims I noticed that they would always start at 100% after shuttnig the engine off. This lets me to believe that the ECU is not keeping memory, therefor not getting a constant positive 10-12 volts.

I know that a fuse (very bottom right hand corner of passenger compartment fuse box) is responsible for the ECU backup, the footlights (when you open your car door) and your stereo settings. Since my footlights work and my stereo never looses its settings I figured the fuse must be good, but I checked to be sure and it is good. While I was looking at the fuse box I checked all fuses which all checked out fine!

Now, how can I find out whether or not infact the ecu is not getting a constant 12V? Anyone know the pin number? What if the pin on the harness side checks out fine?

Thanks for the help!

 

[Woody91GSX]

Check for the MPI fuse where the battery terminal is. Someone told me once that the MPI fuse was part of the ECU memory. In order to reset the ECU you'd unplug the battery, and MPI fuse. I don't know if it will work, but it's worth a shot.

 

[Benji]

Can't be the MPI fuse because without it, there would be no fuel (I think). I know I had to pull the mpi fuse to do a compression test and since you don't want the engine to start you pull the MPI.

Good thought though!