1G No power to ECU

[fastdsm1]

The car has been sitting for a while.I started the car about two months ago,it started fine.Today I go to start the car and I noticed that my apexi is not working.I disreguard it for a minute and start cranking the car over,but the car wont start.I go through the fuses under the dash and they are good.I jump on why the apexi is not working and I jump it to a 12v source and its fine.I check the power wire to the ecu and I find no power.I check every fuse I see, but they all seeem to be good.I need some help on this one.thanks

 

[92awddsm]

The car has been sitting for a while.I started the car about two months ago,it started fine.Today I go to start the car and I noticed that my apexi is not working.I disreguard it for a minute and start cranking the car over,but the car wont start.I go through the fuses under the dash and they are good.I jump on why the apexi is not working and I jump it to a 12v source and its fine.I check the power wire to the ecu and I find no power.I check every fuse I see, but they all seeem to be good.I need some help on this one.thanks

Did you happen to check the underhood fuse box and the fuses on the postive side of the battery? I am willing to bet that is where the problem lies. If I remember correctly, the ecu gets power from underhood fuses, not from passenger compartment fuses.

 

[fastdsm1]

yup... I checked them too,all good

 

[92awddsm]

yup... I checked them too,all good

Did you just do a visual inspection or did you use a multimeter to test them? Sometimes a blown fuse will be hard to see by eye. I would set the meter to ohms and check for continuity between both poles on the fuses.

Is the ecu the only thing not getting power or have you noticed anything else that isnt working at the same time like interior lights, radio, power windows, etc?

 

[fastdsm1]

yea ....I have a multimeter and have checked the fuses....

the only thing that I noticed that was'nt working was the apex,and that, is wired to the ecu.

 

[steve]

No CEL during the first five seconds after you turn the car on indicates that the ECU isn't powering up.

Make sure you have 12v at the MPI fuse on the positive battery terminal?
Then check to make sure you get 12v at pin 103 on the ECU. It comes from the room fuse #19 next to drivers left foot.

The ECU expects to get 12v at pin 110 from the ignition switch when you turn it to run. In response it will pull ECU pin 63 low to turn on the MPI relay. The MPI relay then applies 12v to ECU pins 102 and 107 and the ECU if it's working correctly will boot up, turn the CEL on while the rest of the dash lights go through bulb check and then turn the CEL off.

If you don't have 12v at pin 10 of the MPI relay the ECU will not power up. If you don't have 12v on pin 103 for backup power the settings for long term variables like fuel trims will reset each time you turn the car off.

Since the SAFC is usually attached to the same switched power feed as the ECU from the MPI relay it's likely both aren't turning on.

Steve

 

[fastdsm1]

I found the problem.....fried ecu. thank god I had a spare