Glow plug relal
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Freshman User
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From: Phoenix,N.Y
Glow plug relal
I don't have any control power to my glow plug relay, However there is 12 volts to the supply side ( the big terminal) . I have checked all the fuse's and they are all good. Any idea's Thanks Jeff.
Post Fiend
Joined: Mar 2007
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From: Texas
Not sure what you mean by control power. The 12v supply side is constant from the battery. When the key is turned on, the PCM sends a ground signal to one of the small posts to activate the relay and send the 12v out the other large post to the glow plugs.
What I would consider the control, would be the ground signal.
What I would consider the control, would be the ground signal.
Post Fiend
Joined: Nov 2007
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From: Payson, AZ
Make sure you are checking the GPR and not the AIH (Air Intake Heater) relay.
If you have 2 relays that look the same the one closest to firewall is the GPR.
Also be sure your truck has a GPR and not a GPCM (Glow Plug Control Module). Trucks built for the California market and all Exursions have a GPCM.
Cali truck & EX:
If you have 2 relays that look the same the one closest to firewall is the GPR.
Also be sure your truck has a GPR and not a GPCM (Glow Plug Control Module). Trucks built for the California market and all Exursions have a GPCM.
Cali truck & EX:
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Freshman User
Joined: Apr 2005
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From: Phoenix,N.Y
Not sure what you mean by control power. The 12v supply side is constant from the battery. When the key is turned on, the PCM sends a ground signal to one of the small posts to activate the relay and send the 12v out the other large post to the glow plugs.
What I would consider the control, would be the ground signal.
What I would consider the control, would be the ground signal.
Right i dont have the 12 volts to or at the small post to activate the relay or to allow 12 volts to the glow plugs.
Postmaster
Joined: Dec 2008
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The pcm activates the gpr with a ground signal on one of the small posts. The other small post is vpwr supplied from the pcm as well. I attached a wiring diagram. What problems are you having with the truck? Just cold start issues? Does it start when it's plugged in?
Postmaster
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After looking at the diagram again it looks like vpwr is an input to the pcm. The pcm relay appears to be providing the vpwr to gpr. I would check for key power, B+, and ground with the pcm relay unplugged key on and off.
Senior User
Joined: May 2010
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From: Los Angeles, CA
I've heard a lot about Cali trucks having a GPCM instead of a GPR. I have a 1999 Cali truck and I have a GPR which actually I'm glad about since I can get the Stancor relay someday if I need/want it:
Is my truck an unusual build?
(don't mean to hijack the thread but maybe this will bring out some more info concerning GPR's and GPCM's?)
Is my truck an unusual build?
(don't mean to hijack the thread but maybe this will bring out some more info concerning GPR's and GPCM's?)
Make sure you are checking the GPR and not the AIH (Air Intake Heater) relay.
If you have 2 relays that look the same the one closest to firewall is the GPR.
Also be sure your truck has a GPR and not a GPCM (Glow Plug Control Module). Trucks built for the California market and all Exursions have a GPCM.
Cali truck & EX:
If you have 2 relays that look the same the one closest to firewall is the GPR.
Also be sure your truck has a GPR and not a GPCM (Glow Plug Control Module). Trucks built for the California market and all Exursions have a GPCM.
Cali truck & EX:
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Postmaster
Joined: Dec 2008
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I've heard a lot about Cali trucks having a GPCM instead of a GPR. I have a 1999 Cali truck and I have a GPR which actually I'm glad about since I can get the Stancor relay someday if I need/want it:
Is my truck an unusual build?
(don't mean to hijack the thread but maybe this will bring out some more info concerning GPR's and GPCM's?)
Is my truck an unusual build?
(don't mean to hijack the thread but maybe this will bring out some more info concerning GPR's and GPCM's?)
I believe it's called a gpr shunt or something like that. I'll try to look it up for sure. 99's can be weird trucks.
Postmaster
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Now you guys have smog checks. 
Senior User
Joined: May 2010
Posts: 396
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From: Los Angeles, CA
The smog checks for me are actually pretty easy since I don't have to have a Catalytic Converter. It's really just a visual inspection by people that don't know anything about diesels and a PCM scan for any outstanding codes. Still a waste of my money and time though.
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Posting Guru
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Make sure you are checking the GPR and not the AIH (Air Intake Heater) relay.
If you have 2 relays that look the same the one closest to firewall is the GPR.
Also be sure your truck has a GPR and not a GPCM (Glow Plug Control Module). Trucks built for the California market and all Exursions have a GPCM.
Cali truck & EX:
If you have 2 relays that look the same the one closest to firewall is the GPR.
Also be sure your truck has a GPR and not a GPCM (Glow Plug Control Module). Trucks built for the California market and all Exursions have a GPCM.
Cali truck & EX:
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Freshman User
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From: Phoenix,N.Y
This diagram is the same for a 2001 F-350?