broke down 96
Thread Starter
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Tuned
Joined: May 2004
Posts: 289
Likes: 1
From: Walton, Ky
This issue started a few days after it blew the #9 fuse. After replacing the glow plug relay it stopped blowing that fuse but ran rough and wouldn't idle after I got it going again. That was Thursday afternoon. It ran rough a little on Friday but straightened out. Saturday it ran fine and then this issue started. I'm going to check the IPR and wiring since in my mind it points toward that.
Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
Video shows a classic low voltage situation. Does "alternator checks out" mean that you confirmed that it's actually running 14+ volts while the engine is running, at the batteries? Or was it just bench tested at a shop? Did you check the battery connections and grounds?
Thread Starter
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Tuned
Joined: May 2004
Posts: 289
Likes: 1
From: Walton, Ky
It was bench tested at a shop. I cleaned the batteries up and load tested both batteries. I'm going to clean the grounds and check for 14v at the batteries when I get back out there this weekend. I've been sick all week and working goofy hours so haven't felt like dealing with it.
Thread Starter
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Tuned
Joined: May 2004
Posts: 289
Likes: 1
From: Walton, Ky
Okay here is a little bit of an update. My dad called today and said he had it running and noticed the glow plug relay was so hot he couldn't touch it. He unhooked it and the truck ran fine for the hour he drove it around the property. Im guessing I have a short in the glow plug circuit. Can anyone help me out with a wiring diagram? Has anyone had the harness under the valve cover short out and cause issues? What's the chances the glow plug timer is shorting out keeping the relay energized? I'll have voltage readings and such this weekend.
Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
At least you've got the problem narrowed down considerably; that's good news. Shouldn't be too hard to zero in on the exact cause from here.
There is no "glow plug timer". It's timed by the PCM. It is possible that there's an internal short in the GP relay that's keeping it energized at all times. Also, you need to be sure that it's a true glow plug relay, that is, one with two coil terminals and two contact terminals, and it does NOT ground the coil circuit through the mounting plate.
Also, ohm test the glow plugs, at the UVCH connectors. They should be about 1 ohm each.
Yes, it's possbile for the GP wires to short out under the valve covers.
There is no "glow plug timer". It's timed by the PCM. It is possible that there's an internal short in the GP relay that's keeping it energized at all times. Also, you need to be sure that it's a true glow plug relay, that is, one with two coil terminals and two contact terminals, and it does NOT ground the coil circuit through the mounting plate.
Also, ohm test the glow plugs, at the UVCH connectors. They should be about 1 ohm each.
Yes, it's possbile for the GP wires to short out under the valve covers.
Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
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Post Fiend
Joined: Dec 2010
Posts: 10,121
Likes: 3
From: Orrville, Ohio
If the relay was recently replaced I thi k I would check that again. If it isn't the right relay and it grounds through the mounting bracket it will stay on as long as the key is on.
I'm betting that is what you have there. The PCM activates the relay by supplying the ground for the coil. If the relay grounds thought the mounting plate, the PCM has no way to control it.
I'm betting that is what you have there. The PCM activates the relay by supplying the ground for the coil. If the relay grounds thought the mounting plate, the PCM has no way to control it.
Thread Starter
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Tuned
Joined: May 2004
Posts: 289
Likes: 1
From: Walton, Ky
This is the relay I just put on it.
Relay - Glow Plug | 1996 Ford F350 1 ton P/U 4WD 8 Cylinders F 7.3L Turbo Diesel | AutoZone.com
Relay - Glow Plug | 1996 Ford F350 1 ton P/U 4WD 8 Cylinders F 7.3L Turbo Diesel | AutoZone.com
Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
That's a lot of money for an off-brand relay of unproven quality. For that money, you could've gotten a Stancor. For a LOT less, you could've gotten a Western Plow relay.
Don't trust the listing. Check the mounting base and make sure it is NOT common with either of the coil terminals.
Don't trust the listing. Check the mounting base and make sure it is NOT common with either of the coil terminals.
