P1391 and p1393 are tripping my SES light.

Codes are for Glow Plug curcuit low voltage input. One is for right side other left.

This is on a 2000 Excursion that has had the GPCM removed and replaced with a GPR. My relay has a shunt much like the 99 trucks had. I guess that is how the PCM can determine left or right side. A few others have omitted the GPCM, from what I have read they are not seeing this code.

I would call it intermittant issue. I can clear them and it may take several days for it to come back on, other times it will come on at the next start up. THe truck is new to me and the light did not show up for about a week the first time.

I have tested GP at the 9 pin harness - all are fine(reading 0.8 - 1.3). No burnt pins. Truck runs great. Have popped the driver's side valve cover, the UVCH looked to be completely snapped together. Did the .25 cent mod while there. I did not see any chafed wires, none were touching push rods. I was hoping it would just throw the code for the right side after checking the UVCH. Still throws both codes. I could just ignore it but i dont want a SES light that is burned out becasue of it.

Can a shunt go bad and draw to much current? That SOB get hot, I have scars to prove it!!!!

 

....anybody??

 

You have a custom-wired truck and not many want a piece of this because there is no way to know what was done. People in CA would never get tabs renewed if they remove the GPCM and installed a relay, so this is not a "common" mod.

I can help from raw experience: It's likely the new connectors. Just because they sell crimp connectors and crimpers at Lowes, doesn't mean just anybody should be wielding these gremlin kits. The GPR has pretty high amperage and solid connections with the correct wire and crimps are critical. Give the modified crimps a good tug.

https://www.ford-trucks.com/forums/a...8&d=1344691236

 

From my understanding, the only way to eliminate the GPCM is to replace the engine harness. Im not sure if the pcm gets replaced as well. If it is replaced I would think that these codes would not be in its data base.