Hi Everyone,

I've been digging around on this site for a bit but haven't come up with much.

I have a 2002 Excursion 7.3 PSD. Almost 300k on it, love this truck!

The problem is California smog check. The Comprehensive Component checks reset to incomplete every time I turn the truck off. If I drive it around for a bit, my scanner goes green and everything is ready. If I turn the key off, though, when I re-start the truck I have to walk back through the drive cycle every time.

I'm currently running an Edge tuner on it. This happens with the tune on, returned to stock, and was happening before I put the tuner on. The batteries are healthy, everything else seems to be in pretty functional working order.

Any ideas would be greatly appreciated. This turns into a giant pain in the butt every time I have to smog

-PC

 

Check fuse F36.

It supplies ALWAYS HOT power to the PCM for its "Keep Alive Memory" aka "KAM".

If the fuse is not blown:
1) Verify it is actually passing power by checking the voltage at both test points with it in-circuit.
2) Inspect the fingers that hold the fuse in place for looseness, corrosion, or other damage.
3) Check continuity between the load terminal of F36 and PCM connector C175 Pin 55.
4) If power is available all the way to pin 55, then there's probably an internal failure in the PCM's KAM circuitry.

If the fuse is blown, replace it and see if the replacement also blows. If it does:
1. Disconnect C175 and retest with a new fuse. If it still blows, there's a short to ground on the load side of F36 (wiring harness or internal to fusebox).
2. If it does not blow, there's an internal short to ground on the KAM power circuit inside the PCM.

 

Replaced the fuse, verified power, set the monitor, and then stopped for coffee. When I restarted it a few minutes later it had reset again.

Im guessing the KAM is bad somehow.

Correct me if I’m wrong but this thing isnt learning fuel trims and tune info right? Im good driving around with it resetting the way it does?