Another GPR question (Help)
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Another GPR question (Help)
OK, have 99 F-350 psd 125K. First cold weather here in N. Michigan I begin having cold start problems, read a few threads talk to our Mechanics at work, he though that the GPR was burnt out. I have replaced the GPR and all 8 GP's, still having starting problem when cold, plug in and OK. Here is my question, Tested for Voltage on all 4 terminals on the GPR, with key on have 12.4 volts on power in, 12.4 on power out to glow plugs, 12.4 volts on small terminal facing front of truck, but I have no power to the small terminal facing the rear, my understanding is that all four post should have 12 volt. What sensor feeds power to the rear facing small terminal on the GPR ? I think that this sensor may be my problem. Any help is appreciated. Thank you!
Hotshot
Joined: Jan 2002
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From: La La Land
You'd better HOPE that the unknown (to you) "sensor" isn't the problem. It's a ground that comes from the Powertrain Control Module, the engine's "brain". Expensive.
I posted some testing with a DVM that you can do at:
https://www.ford-trucks.com/forums/s...d.php?t=426789
Pop
I posted some testing with a DVM that you can do at:
https://www.ford-trucks.com/forums/s...d.php?t=426789
Pop
Last edited by SpringerPop; Dec 11, 2005 at 12:53 PM.
Post Fiend
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From: Carhenge
If the glow plug relay is actuated (you are getting power out to the glowplugs) then I think you have to have current "out" the small terminal, because it is the ground for the control current to the relay. If it were not, the gpr would not actuate, would it?
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Thanks springerpop probably not what I wanted to hear. But - are there any componants feeding information to the PCM that may prevent it from grounding and completing the circuit? and could there be eny other explanations as to why the truck does'nt start cold when there seams to be power going to the GP's.
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From: Ridgecrest, CA
E.T. 101 - when the gpr is energized, you'll have 12V on both big terminals and the front little terminal. The rear little terminal should be 0V or very close to 0V. When the gpr is de-energized, you'll have 12V on both little terminals and on the passenger side big post. The pcm provides the ground (0V) to the relay and also receives info from 2 other sensors to limit or switch in/out the "on" time of the relay. There's a post from me that Kwik provided excellent info, just do a search for glow plugs, gpr, etc (I forgot what I titled the post). It was only a couple of weeks ago.
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Thanks Roaky81, it sounds like everything is working fine, except that my truck still won't start when cold without being plugged in. Any idea's? Which sensors should I be checking next? and where are they located? All help is appreciated I'm desperate!
Thanks glowplug
Thanks glowplug
Fleet Owner
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From: Rio Rico, AZ.
Originally Posted by glowplug
Thanks Roaky81, it sounds like everything is working fine, except that my truck still won't start when cold without being plugged in. Any idea's? Which sensors should I be checking next? and where are they located? All help is appreciated I'm desperate!
Thanks glowplug
Thanks glowplug
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From: Ridgecrest, CA
I'm gonna look into the Engine Oil Temperature sensor. If it reads or stuck on a temp of 55' C or higher, it'll tell the PCM not to give the ground to the GPR. I have a post called Glow Plug 101 that's dealing with my issue of no ground at the GPR.