gpr led stays on
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Lead Driver
Joined: Sep 2010
Posts: 7,793
Likes: 50
gpr led stays on
weird thing today. Fired up truck, let it warm up then cruised to H.D. With truck already idling for 10min, and a 5 mile trip to Depot, the gpr-led light was still on. So, i pulled into the Napa enroute, and they only had the gpr110 at $75.00...NO WAY. So, popped hood and disconnected everything on the "outlet" lug of gpr....SO,ami on right track that the gpr is bad or something else amiss...
Trailering
Joined: May 2012
Posts: 21
Likes: 0
From: south puget sound, WA
I had a gpr shorted "on" on a tractor and it would kill the battery quickly while the engine was shutoff. Ended up manually energizing the GPs until I could get a new relay.
If that GPR is stuck on then I would be worried that it is not shutting off ever, lotta amps going to those GPs all the time. Is the GP circuit hot with key off?
If that GPR is stuck on then I would be worried that it is not shutting off ever, lotta amps going to those GPs all the time. Is the GP circuit hot with key off?
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Lead Driver
Joined: Sep 2010
Posts: 7,793
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nope...with key off, the led goes out. I've had it undone since it happened. Its around mid/high 60's here at 5am so i think im good til i smog her...
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Elder User
Joined: Sep 2011
Posts: 979
Likes: 4
From: Vancouver
That is a very unusual way for the GPR to fail. Usually if it fails with the output energized, like you have, the relay stays in that position whether the key is off or on. This would result in the GPR light staying on and the batteries going dead from the glow plugs staying energized. Since the light is turning off when the key is off, this means that the PCM is commanding the GPR to stay energized, but that signal turns off when the key is off.
Even if the coolant or air temp sensor is bad and falsely indicates a very low temp, the PCM should time out the GPR circuit. One thing to try is to disconnect both batteries and then reconnect after several minutes. Sometimes strange computer actions can be reset with a power off reset.
If that does not work, check the coolant temp sensor and air temp sensor with a multimeter or scan for codes.
Another possibility is that there is a pair of wires that "mouse technicians" have shorted together. Or a harness has rubbed in some of the famous places under the hood, resulting in two or more wires shorting together. The harness would have to be the one that leaves the PCM and eventually ends up at the GPR.
Please let us know what you find. This is a weird one. Larry
Even if the coolant or air temp sensor is bad and falsely indicates a very low temp, the PCM should time out the GPR circuit. One thing to try is to disconnect both batteries and then reconnect after several minutes. Sometimes strange computer actions can be reset with a power off reset.
If that does not work, check the coolant temp sensor and air temp sensor with a multimeter or scan for codes.
Another possibility is that there is a pair of wires that "mouse technicians" have shorted together. Or a harness has rubbed in some of the famous places under the hood, resulting in two or more wires shorting together. The harness would have to be the one that leaves the PCM and eventually ends up at the GPR.
Please let us know what you find. This is a weird one. Larry
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Lead Driver
Joined: Sep 2010
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UPDATE
Alrighty...finally got around to this. I re-installed the wires that i removed on the "output" lug, and thus, led light stayed on. So, a week later, my NEW gpr comes in and finally get around to installing it this morning. Sure enough, damn led light is still ON! NOW WHAT?
Elder User
Joined: Mar 2012
Posts: 534
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From: Quaker Hill
I know this may be frowned upon, but you could wire your GP to a manual on/off switch in the cab. Obviously, the stock way is best, but if the PCM is telling your GPR to stay on, a switch is cheaper than a PCM. Not a great plan, but plan B's are great to have in your back pocket.
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Lead Driver
Joined: Sep 2010
Posts: 7,793
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guess i need to test #101 on pcm wire....thanks woodnthings...great video
glow plug relay remote wire always live!! - Ford Powerstroke Diesel Forum
glow plug relay remote wire always live!! - Ford Powerstroke Diesel Forum
Lead Driver
Joined: Jun 2004
Posts: 6,334
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From: Amarillo, TEXAS!
With the key on, one of the small wires on the glow plug relay should have +12V to it constantly. The other small wire is the ground signal from the PCM; probably a purple wire with an orange tracer. If that signal wire has continuity to ground with the key off, you have a short to ground on that circuit. If that's the case, disconnect the 42 pin connector and retest. If the circuit still has continuity to ground, the short is somewhere in the engine harness. If not, it's somewhere in the body harness.
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Lead Driver
Joined: Sep 2010
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im one of them, and im sure im not alone, when you read a thread, ask questions, repost..etc, just for the OP to leave info, if not vital, information out. Well, i did just thtat.
I failed to mention, that my gpr IS sharing both sets of harnesses/wires...original wiring to gpr for the gpr itself, and also, the wires that went to the AIH relay. I combined them, 2+yrs ago...With that said, i'll remove the AIH wires from the gpr and see what happens. Maybe, its the aih wire that causing the gpr to stay lit....sorry guys, and thanks for the help
I failed to mention, that my gpr IS sharing both sets of harnesses/wires...original wiring to gpr for the gpr itself, and also, the wires that went to the AIH relay. I combined them, 2+yrs ago...With that said, i'll remove the AIH wires from the gpr and see what happens. Maybe, its the aih wire that causing the gpr to stay lit....sorry guys, and thanks for the help