no current to glow plug relay

[dtelep]

Motor: '97 7.3 powerstroke

Symptom: Truck turns over but will not start. Glow plug light on dash won't light.

Progress to date:

- tested current to front post of glow plug relay (hot lead) when ignition was off - 12 volts.

- tested current to back post (to GP) when ignition was on - no current.
- tested current to small posts - no current.
- jumped 12 volts directly from battery through the small posts - relay closed, GP light on dash turned on, engine started.
- removed positive jump from battery to small GPR post, engine kept running.
- removed negative jump from battery to small GPR post, engine died.

So . . . It appears there is a power supply issue to the GPR. Is it a bad PCM? Where is it located? How do I test? Could it be a ground issue? Could it be something else? Any help is very much appreciated.

David

[CHUCK]

sounds like a bad starter solinoid on the fenderwell....

[dtelep]

Chuck,

The starter solenoid feeds current to the GPR? If the starter solenoid was bad, how could the starter motor turn over?

[Chop]

Sounds as if the #22 fuse is blown.This is the one that feeds the fuel warmer and plug controller and of course the wait to start light

[JSchuricht]

If the truck died after removing power from the GPR, you have some more serious issues than a bad relay. Could be a bad ground or the PCM.

[dtelep]

Chop: Where is #22 located? I checked the fuse box in the cab and couldn't find any blown fuses. Is there another fuse location?

JSchuricht: The engine does not die when power is removed from the GPR but when the ground is removed. When I remove the positive jumper from the GPR, the truck continues to run fine. It's only when the ground is removed.

[Chop]

The box is next to brake booster,the cover has an index inside.If the fuel heater shorts out the fuse will pop.If thats the case unplug heater at the fuel bowl on drivers side midway .You could test light this wire,it should be hot with ignition on

[retmotor]

When the #22 plug is blown, the pickup won't run.

It does go out though so knowing where it's at is just a good idea.

[retmotor]

Originally Posted by dtelep

...
- tested current to back post (to GP) when ignition was on - no current.
- tested current to small posts - no current.
- jumped 12 volts directly from battery through the small posts - relay closed, GP light on dash turned on, engine started.
- removed positive jump from battery to small GPR post, engine kept running.
- removed negative jump from battery to small GPR post, engine died...

Baffles me...

[dtelep]

Originally Posted by Chop

The box is next to brake booster,the cover has an index inside.If the fuel heater shorts out the fuse will pop.If thats the case unplug heater at the fuel bowl on drivers side midway .You could test light this wire,it should be hot with ignition on

Thanks Chop . . .

Is that fuse box in the cab or under the hood?