Glow Plug Relay Stays On
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From: Banks, OR
Glow Plug Relay Stays On
Just got finished replacing the under valve cover wiring harness and two burnt plugs. Put it back together, started it up, and the glow plug relay started to smoke. I put a test light on the relay and it didn't turn off. Thought I needed a new relay, but the new unit does the same thing. I'm worried that if I run it too long I'll burn up all my new wiring. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com
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I would think that it’s the glow plug controller, but I read somewhere that the glow plugs in this era Powerstroke are controlled by the PCM.<o></o>
Any ideas?<o></o>
fficeffice" /><o></o>I would think that it’s the glow plug controller, but I read somewhere that the glow plugs in this era Powerstroke are controlled by the PCM.<o
></o>Any ideas?<o
></o>
Postmaster
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From: Medford Oregon
Yes glow plug relay on time is controlled by the PCM. What year truck do you have? On my 97 if I disconnect the small PPL/ORG wire on the relay (it goes to the PCM) then the relay should not activate. The PCM grounds that wire. Look for maybe a short on that wire enroute to the PCM.
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From: Banks, OR
This is a '95 F-350. The smaller wires on the relay are both red, go into a plug, and come out (1) pink and (1) red (with green stripe) on the other side of the plug. The wires quickly disappear into the covered wire harness.
Where is the PCM? Is it the silver metal box under the hood near the fuse box on the drivers side? Or is it under the dash where you plug in a code reader?
Where is the PCM? Is it the silver metal box under the hood near the fuse box on the drivers side? Or is it under the dash where you plug in a code reader?
Hotshot
Joined: Aug 2006
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It may be the wrong relay ,,,It needs to be an isolated ground unit,,meaning the case isn't grounded ,the PCM adds the ground when called for ...
You should be able to test the on time from the ground wire from the PCM with a test light...
You should be able to test the on time from the ground wire from the PCM with a test light...
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Joined: Sep 2007
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From: Medford Oregon
This is a '95 F-350. The smaller wires on the relay are both red, go into a plug, and come out (1) pink and (1) red (with green stripe) on the other side of the plug. The wires quickly disappear into the covered wire harness.
Where is the PCM? Is it the silver metal box under the hood near the fuse box on the drivers side? Or is it under the dash where you plug in a code reader?
Where is the PCM? Is it the silver metal box under the hood near the fuse box on the drivers side? Or is it under the dash where you plug in a code reader?
PCM is located in the area you mentioned but so is the IDM. I don't have a picture of it but somebody will probably post one.
You should have +12 volts on both your smaller Red wires on the Glow Plug Relay for the relay to be OFF. To be ON one of the Red wires will be at ground (via the PCM).
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From: Medford Oregon
Good point .. what Relay did you purchase ??
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From: Banks, OR
For what its worth, I replaced it with the same relay that has been on the rig. I'd say its not grounded through the base. The metal base is riveted to the plastic case of the relay. I checked to be sure by touching the base to the neg battery post and put the test light on the pos battery post, then touched the tester to all the posts on the relay - didn't light the tester, didn't complete a circuit... not grounded through base.
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From: Banks, OR
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From: Banks, OR
I turn the key on. One of the small posts has 12+ volts. The other has .5 volts. (Doesn't turn a test light on). By what you said, that indicates relay is on. I didn't see any obious signs of wear on the wire harness across the valve cover.
I'm stumped.
I'm stumped.
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From: Banks, OR
TJBEGGS- I guess I was over worried! I timed it and the GPR shut off @ 65 seconds. The relay on my '92 cycles so fast that I was worried about burning up wiring on the '95. Sorry for all the commotion about nothing - thanks for the advice!
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