Glow Plug Relay Question
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Glow Plug Relay Question
Ok so i tested my old gpr this aft. to see if it was working wasn't getting any power to the gp side of the relay so went out purchased a new unit installed it tested it with the key on and same thing no voltage on the glow plug side! so i check the smaller post with the red wire it has voltage and the opposite orange wire does as well now i read somewhere if you ground the orange post the relay will click and give power to the large gp post which mine does it goes click and power goes to gp's but how come when i just turn the key on it does not do this?
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That is a ground signal sent by the pcm. Could be the wiring, pcm bad, or external sensor. I think it uses engine oil temp, temperature, and baro sensors. The baro sensor is internal to the pcm. You could install a push button in the cab until you figure it out. Just run a wire to ground then to the switch and to the gpr.
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so if that is hooked to the pcm and the truck was warm when i did this would the pcm be telling the glow plugs not to start due to the fact the engine is still warm? I figure i ll let it sit overnite and try it and if still nothing ill rig up a led light and maybe a momentary switch to smaller post and say screw it to the pcm !
Post Fiend
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From: Payson, AZ
I did not know that.
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Postmaster
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re
This was the source on the info:
PowerStroke diagnosis
Quote from it:
As with performance problems, you first have to start with the Preliminary Checks and Code Retrieval.
After checking the preliminaries, KOEO and Continuous codes, and the concern happens cold only, check the glow plug system function. Unplug the Engine Oil Temperature sensor and turn the key to the run position. This will cause the PCM to close the glow plug relay for the maximum of two minutes. Check for voltage to and from the glow plug relay. The control voltage is supplied by the ignition switch and the PCM controls the ground based on EOT.
PowerStroke diagnosis
Quote from it:
As with performance problems, you first have to start with the Preliminary Checks and Code Retrieval.
After checking the preliminaries, KOEO and Continuous codes, and the concern happens cold only, check the glow plug system function. Unplug the Engine Oil Temperature sensor and turn the key to the run position. This will cause the PCM to close the glow plug relay for the maximum of two minutes. Check for voltage to and from the glow plug relay. The control voltage is supplied by the ignition switch and the PCM controls the ground based on EOT.
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Post Fiend
Joined: Nov 2007
Posts: 9,549
Likes: 14
From: Payson, AZ
This was the source on the info:
PowerStroke diagnosis
PowerStroke diagnosis
Great source isn't it? Been there many times.
My retension isn't what it used to be.
Glad we got you young ones around.
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so this mornin i check for the 12v at the glow plug side and it was there u could hear the relay energized so go to crank it now i left it unplugged for the nite and it was probably -8 to -10 degrees celcius i guess and the first try it was a slow crank and nothing i stopped got out and looked around checked battery voltage then tryed again it fired after a couple cranks and it would never do this befor so i was looking for an led to rig up but nothin was open so i drove the thing around all day haha
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snowcrash47
Pre-Power Stroke Diesel (7.3L IDI & 6.9L)
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May 2, 2012 01:26 PM
