GPR issues!!

[usafracer21]

I have a 2001 f250 and having an issued ive seen discussed but no conclusions. My gpr solenoid is not working. its not a bad solenoid ive tested it already. im getting 12v on both small poles with the key turned on. I took the pcm wire off and i get a good ground when its not connected to the relay but when its connected its not grounding the relay, its getting the 12v. Any help please!!?

[NoRalPh]

Take the 2 sm wires off the GPR, one has 12v in it with the key On. The other, as you apparently know, goes to the PCM so it can supply it with ground when the PCM decides it needs to be activated. BUT, once you connect that 12v wire, BOTH side are going to show 12v (the power is just passing through the coil inside and YOU are supplying the path to ground through your meter/testlight).

SO, if you manually ground the side of the relay that goes to the PCM you should hear it "click" and find 12v on Both of the large terminals. Once activated, the nearly 200A draw of the GlowPlugs will draw-down that voltage immediately some (but Not less than @10v). THAT's how you'll know the Relay & GPs are working

[usafracer21]

Correct when I ground the relay with a jumper, it's working correctly.. This is the only way it will work

[NoRalPh]

OK but, I thought I read you had a good path to ground on the PCM wire - no?

" I took the pcm wire off and i get a good ground when its not connected to the relay"

Those two things don't make sense to me,,,, if the PCM wire is supplying the same thing as your manual grounding then it should work! The PCM decides to use the GPs based mainly on the EOT (Engine Oil Temp) sensor. It should supply ground to that wire for 30sec - 2min when it sees the engine is cold.

Are you sure it's doing that?

[usafracer21]

Ya I don't understand it... I take the PCM wire off and shoot the ground wire on my multimeter with it and I get ground, but when it's on the relay its not making ground..