Another No Start Problem...
Postmaster
Joined: Mar 2004
Posts: 3,897
Likes: 8
I just tested the GP's with an ohmmeter and all but one of them appear to be working. However, lacking on GP should not be causing this significant of an issue. The GPR checks out on the 2 larger posts, but the smaller post that should have power when the switch is on does not. I just started the truck after a medium length cranking sequence. Before doing so, I let the GPR run until the buzzing slowly faded away. The truck started after this and ran fine. However, after shutting it down, waiting a few minutes and trying again, I got nothing. This time, the GPR buzzed loudly then "clicked" off. No start...
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Senior User
Joined: Feb 2015
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According to all that I've read, when the key is "ON", there should be power on the smaller post closest to the passenger side on the GPR. At no point, even when I had it running briefly, was there power on that post.
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Senior User
Joined: Feb 2015
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The new one does not buzz. Maybe a faint buzz only, but barely anything. The old one had a loud buzz that you could feel on the GPR housing.
Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
But just to eliminate any GPR issue, and to eliminate the other major issue with that circuit (fuel filter heater), disconnect that red/green wire (and tape it off) as suggested above. Also disconnect the fuel filter heater. Same color wire, flat blade single terminal connector on the driver's side of the fuel bowl. THEN, connect a jumper cable between the two big terminals on the GPR (or, alternately, from the battery positive to the "load" side of the relay, the terminal that goes to the GPs). Have it on for 10-15 seconds to energize (or at least it SHOULD) the glow plugs. Then remove it, and go try to start the truck.
Do you have a decent charge in the batteries at this point?
Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
^^^^ Good idea; the GPR has even been know to fail such that it crosses the coil and contact circuits, so it's always energized. And it will even "backfeed" power to the PCM even when fuse #22 is blown. So disconnecting it might make such issues apparent.
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Thread Starter
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Senior User
Joined: Feb 2015
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What color is the wire on that terminal? It's useless to go by physical position, because neither the coil circuit nor the contact circuit of the GPR are polarized, and the wires may have been switch by some PO. If it was the red/green wire you tested, then yes, it should have voltage whenever the key is in the RUN position. That circuit also energizes the PCM, so if you are getting the WTS light, the circuit itself is good.
But just to eliminate any GPR issue, and to eliminate the other major issue with that circuit (fuel filter heater), disconnect that red/green wire (and tape it off) as suggested above. Also disconnect the fuel filter heater. Same color wire, flat blade single terminal connector on the driver's side of the fuel bowl. THEN, connect a jumper cable between the two big terminals on the GPR (or, alternately, from the battery positive to the "load" side of the relay, the terminal that goes to the GPs). Have it on for 10-15 seconds to energize (or at least it SHOULD) the glow plugs. Then remove it, and go try to start the truck.
Do you have a decent charge in the batteries at this point?
But just to eliminate any GPR issue, and to eliminate the other major issue with that circuit (fuel filter heater), disconnect that red/green wire (and tape it off) as suggested above. Also disconnect the fuel filter heater. Same color wire, flat blade single terminal connector on the driver's side of the fuel bowl. THEN, connect a jumper cable between the two big terminals on the GPR (or, alternately, from the battery positive to the "load" side of the relay, the terminal that goes to the GPs). Have it on for 10-15 seconds to energize (or at least it SHOULD) the glow plugs. Then remove it, and go try to start the truck.
Do you have a decent charge in the batteries at this point?
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Senior User
Joined: Feb 2015
Posts: 121
Likes: 1
I don't know. I can see how it could send a faulty signal. One thing is for sure...disconnecting it didn't help!
Hotshot
Joined: Mar 2012
Posts: 10,590
Likes: 382
From: Texas
Check the wiring to the IPR pigtail and make sure it's not rotted away from diesel fuel. Maybe juggle the pigtail and try to start again. If it starts, jiggle those wires and see if it shuts down. Ask me how I know this.
Postmaster
Joined: Mar 2004
Posts: 3,897
Likes: 8
it can send a faulty signal but I don't think it would create a no start
