With the key in the on position (not started) does the PFC commander light up?


trying to figure out if my car won't start due to PFC issues or something else. wondering if there's a short somehwere.

 

Yes

 

yeah, as soon as I write this and go back out to check it, it lights up.


I even put back in the stock ecu to make sure that the PFC wasn't gone altogether and it did the exact same thing. Crank no start.... (not a plug/fuel issue)


It's obviously a short/problem in the ECU wiring system. Does anyone know know of any possible culprits? Or a better way to wire the ecu? Could it be the EGI Main Relay? Ignitor?

 

Sounds like you have a loose ground.

 

i'll double check them. both of the grounds were attached to the PFC snuggly. In fact, that was my first thought that maybe the nut that the 2 grounds are screwed down with had backed itself off maybe...... they were still snug.

thanks for the reply, others are welcome to chime in.

 

Actually there are four main gounds to the PFC and two major 12v positives, if any of these are loose the PFC (or the stock ECU) will not power up.

PFC grounds connector #4

4A, 4B, 4C, 4D

12v PFC connector #1

1A ,1B

 

does the switched power come from the EGI main relay and 30A EGI Fuse?

 

UPDATE:

Banzai Racing was correct. The 4C ground had some serious problems. Only 4volts out of the needed 12volts when the multimeter was hooked up.

Instead of tracing the brown wire's ground point, I spliced in a new ground (solder, heat shrink, electrical tape) and ran it to a visible grounding point on the vehicle.

Problem solved. For those that find this thread after it's end, get a multimeter and start checking. The best route is as follows:

Check voltage for pins:
1A, 1B (with key on/off)


If no voltage:
Test the main relay and fuses.


If voltage:
Check grounding pins with constant current pin 1B:
4A, 4B, 4C

If this checks out:
Do a ohm/continuity check through the ecu on the above mentioned grounding pins w/ constant current/key current. (you're testing the same pins as you did above but THROUGH the ecu) If no continuity on those pins, then try another ecu.


Essentially (from a few hours in the thick of having my car stranded in a parking structure) the diagram goes:

Battery -> EGI Fuse/Relay -> ECU

Pages F-153-ish in the FSM.