Glow Plug Relay
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Junior User
Joined: Dec 2004
Posts: 60
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Glow Plug Relay
Hi guys/gals,
It is getting damn cold up here in Maine and decided I'd check the GPR after a friend suggested it, saying they burnout over time. the truck is a 2003 with 245,XXX on the clock. I watched 2 videos and read 2 different forum posts on how to check it, seemed very easy. Everyone says check the "rear" relay, but I only have 1.
I check it with a volt meter and it was 12.8 on the one side and 0 on the other. With key on it still reads 0 volts.
Just wondering if i checked the right relay since there was only 1 there. If so, i'll go get a new relay tomorrow. Truck also got new batteries today. If i don't plug it in at night and it gets to 0 degrees, it won't start.
Thanks for the help. Here is a picture of my setup.
It is getting damn cold up here in Maine and decided I'd check the GPR after a friend suggested it, saying they burnout over time. the truck is a 2003 with 245,XXX on the clock. I watched 2 videos and read 2 different forum posts on how to check it, seemed very easy. Everyone says check the "rear" relay, but I only have 1.
I check it with a volt meter and it was 12.8 on the one side and 0 on the other. With key on it still reads 0 volts.
Just wondering if i checked the right relay since there was only 1 there. If so, i'll go get a new relay tomorrow. Truck also got new batteries today. If i don't plug it in at night and it gets to 0 degrees, it won't start.
Thanks for the help. Here is a picture of my setup.
Lead Driver
Joined: Jun 2004
Posts: 6,311
Likes: 577
From: Amarillo, TEXAS!
That relay should be for the intake air heater. The aluminum module with the 2 harnesses plugged in to it looks like a glow plug control module. Is it a pickup or an Excursion? The Excursions also used GPCMs rather than relays.
Senior User
Joined: Sep 2013
Posts: 498
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From: Hagerstown, MD
It looks like you have a California truck. As Pikachu said, Excursions and CA trucks were outfitted with Glow Plug Control Modules instead of a GPR. The relay you see in the picture is for the Air Intake Heater (AIH). It is almost never used due to the particular parameters that must be met and many delete it.
Let's back up a step. When you say it won't start, are you getting smoke from the tailpipe? How long do you let the glow plugs cycle before cranking? They will stay energized for up to 1-2minutes depending on certain parameters and the particular truck.
Let's back up a step. When you say it won't start, are you getting smoke from the tailpipe? How long do you let the glow plugs cycle before cranking? They will stay energized for up to 1-2minutes depending on certain parameters and the particular truck.
Lead Driver
Joined: Jun 2004
Posts: 6,311
Likes: 577
From: Amarillo, TEXAS!
It almost has to be a CA emissions package if it's a pickup. It should throw a code and set the service engine light if any of the glow plugs or the control module are bad. You might be able to check your VIN using the VIN Decoder link in the Tools dropdown menu at the top of the page to confirm CA emissions, but I'm not sure if that will show up there or not.
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Junior User
Joined: Dec 2004
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If the ambient temp is 0 or below and the truck is not plugged in, I usually cycle the glow plugs twice and try and start it. I do get a little smoke from the exhaust like it's trying. This past week it would turn over but just not start. I eventually ran the batteries dead from trying. I run additive all winter to keep the fuel from gelling too.
When the truck is plugged in, it starts immediately and will blow cab heat almost as fast.
When the truck is plugged in, it starts immediately and will blow cab heat almost as fast.
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Senior User
Joined: Sep 2013
Posts: 498
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From: Hagerstown, MD
Good point Stewart. I tend to forget that. When you say cycle the plugs, do you just go until the indicator on the dash goes out? Or do you cycle twice at 1-2 minutes apiece?
Have you drained your fuel bowl recently? We had a 97 7.3 that collected separated water in the bottom of the bowl and froze. The fuel bowl heater wasn't working properly. I've never seen this on a Super Duty but I would imagine the same thing can happen.
Have you drained your fuel bowl recently? We had a 97 7.3 that collected separated water in the bottom of the bowl and froze. The fuel bowl heater wasn't working properly. I've never seen this on a Super Duty but I would imagine the same thing can happen.
Lead Driver
Joined: Jun 2007
Posts: 7,760
Likes: 27
From: Hampton, Maryland.
Waiting for the light to go out on the dash is not nearly long enough on a truck in Maine. Wait at least 60 seconds and they try starting. Depending on ambient, you may want to cycle the key and do it again. Try that and see if it helps.
Elder User
Joined: Dec 2002
Posts: 797
Likes: 1
From: UT
ALOT of us wire in a cheap LED light from radio shack to show when the GPR is active, before we start our trucks. Like everyone has said above the GPR will stay on for 1min+.
It makes me wonder why Ford even bothered installing the Wait To Start light, it doesn't function properly!
It makes me wonder why Ford even bothered installing the Wait To Start light, it doesn't function properly!