Block Heater
Elder User
Joined: Mar 2012
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From: Quaker Hill
https://www.ford-trucks.com/forums/1...t=GPR+location
Ok. I'm not great at this, but try clicking that link. There's a few pics if the GPR relay, and also the Air Intake Heater relay. I'd refer to post 9 on that link by Shake n bake. His perspective is standing on the passenger side of the engine bay looking towards the drivers side. Hold you voltmeter ground to the battery ground. Hold the positive lead to a big post if the relay. There's 2. One will read hot all the time. The other large post should come on after you turn the key to the on position, and should stay hot for around 90 seconds on a cold engine. If that happens, your GPR is working correctly. If not, it's bad. You don't usually get a so so reading in a GPR. It either works or it doesn't. Truth is, your scanner thing a ma bob is probably right. But it's a computer....
Ok. I'm not great at this, but try clicking that link. There's a few pics if the GPR relay, and also the Air Intake Heater relay. I'd refer to post 9 on that link by Shake n bake. His perspective is standing on the passenger side of the engine bay looking towards the drivers side. Hold you voltmeter ground to the battery ground. Hold the positive lead to a big post if the relay. There's 2. One will read hot all the time. The other large post should come on after you turn the key to the on position, and should stay hot for around 90 seconds on a cold engine. If that happens, your GPR is working correctly. If not, it's bad. You don't usually get a so so reading in a GPR. It either works or it doesn't. Truth is, your scanner thing a ma bob is probably right. But it's a computer....
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Joined: Sep 2011
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From: Millstone, NJ
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Senior User
Joined: Jun 2013
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From: Paw Paw
So when you bridged the GPR where exactly did you put the screw driver? I relation to that picture.
Elder User
Joined: Sep 2011
Posts: 659
Likes: 1
From: Millstone, NJ
Not sure what the control module you're talking about is.
Slip the screwdriver between the two contacts (big posts) on the GPR (horizontally). Just make sure the screwdriver is touching both of the posts at the same time.
I will try to get a pic tomorrow if you can't figure what I'm talking about. I suck at editing pictures.
Slip the screwdriver between the two contacts (big posts) on the GPR (horizontally). Just make sure the screwdriver is touching both of the posts at the same time.
I will try to get a pic tomorrow if you can't figure what I'm talking about. I suck at editing pictures.
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Senior User
Joined: Jun 2013
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From: Paw Paw
Not sure what the control module you're talking about is.
Slip the screwdriver between the two contacts (big posts) on the GPR (horizontally). Just make sure the screwdriver is touching both of the posts at the same time.
I will try to get a pic tomorrow if you can't figure what I'm talking about. I suck at editing pictures.
Slip the screwdriver between the two contacts (big posts) on the GPR (horizontally). Just make sure the screwdriver is touching both of the posts at the same time.
I will try to get a pic tomorrow if you can't figure what I'm talking about. I suck at editing pictures.
Oh I know exactly what you are talking about on got on riffraff to see what they carry and I know the "posts" you mean.
Put pictures from you would be awesome!
Elder User
Joined: Sep 2011
Posts: 659
Likes: 1
From: Millstone, NJ
The Glow Plug Control Module only came on California trucks and Excursions. All other trucks got the Glow Plug Relay.
https://www.ford-trucks.com/forums/a...9&d=1257966356
Elder User
Joined: Dec 2012
Posts: 841
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From: Monroe, MI
Get yourself a plug in volt meter that plugs into the dash power port. I bought this from Wally world..
You should see the following reading if the GPR is working.
1) when plugged in you should see 12.5v
2) when you turn the key to on and the wait to start light comes on it should read 11.5v. glow plug relay is 'on'.... if the voltage does not 'drop' then you may have a problem with the relay.
3) when the 'wait to start' light goes out (and you had the voltage drop to 11.5v) if it is really cold then cycle the glow plugs again to get the chamber really hot. Now turn the key to start the truck. your voltage meter will drop to about 11v. If the meter drops below 10.5 the truck Will Not Start as you need at least 10.5v for it to start.
4) when the truck starts, the voltage should be 12.5v. When the GPR shuts off the voltage will slowly rise to 14.5v. this last number of the voltage is the output of the alternator.
5) Do you have any questions?
You should see the following reading if the GPR is working.
1) when plugged in you should see 12.5v
2) when you turn the key to on and the wait to start light comes on it should read 11.5v. glow plug relay is 'on'.... if the voltage does not 'drop' then you may have a problem with the relay.
3) when the 'wait to start' light goes out (and you had the voltage drop to 11.5v) if it is really cold then cycle the glow plugs again to get the chamber really hot. Now turn the key to start the truck. your voltage meter will drop to about 11v. If the meter drops below 10.5 the truck Will Not Start as you need at least 10.5v for it to start.
4) when the truck starts, the voltage should be 12.5v. When the GPR shuts off the voltage will slowly rise to 14.5v. this last number of the voltage is the output of the alternator.
5) Do you have any questions?
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Senior User
Joined: Jun 2013
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From: Paw Paw
I will get pics tomorrow. Easier done than said lol.
The Glow Plug Control Module only came on California trucks and Excursions. All other trucks got the Glow Plug Relay.
https://www.ford-trucks.com/forums/a...9&d=1257966356
The Glow Plug Control Module only came on California trucks and Excursions. All other trucks got the Glow Plug Relay.
https://www.ford-trucks.com/forums/a...9&d=1257966356
More Turbo
Joined: Mar 2006
Posts: 582
Likes: 2
From: Eads, TN
I don't see how that instrument will check the GPR. It looks like it is testing the battery and alt./charging system.
Checking the GPR with a volt meter is the best and easiest method....IMO.
Checking the GPR with a volt meter is the best and easiest method....IMO.
Elder User
Joined: Dec 2012
Posts: 841
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From: Monroe, MI
I just don't see why it wouldn't work if you read the whole instructions he gives, I've also heard of a lot of guys using methods like that to monitor it and make sure its working
More Turbo
Joined: Mar 2006
Posts: 582
Likes: 2
From: Eads, TN
Like I said, I'm not familiar with that instrument. If it does actually test the GPR I think it would be a cool thing to use.
Elder User
Joined: Dec 2012
Posts: 841
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From: Monroe, MI
Well you have so many volts just from the batteries alone, apparently its 12.5 now you turn the key to on, to turn the relay on to run the glow plugs if the relay works you get a voltage drop to 11.5 and then it drops again when you crank it over hopefully no less then 10.0
Fleet Mechanic
Joined: Nov 2010
Posts: 1,408
Likes: 249
From: Ringgold, Ga
An easier way to check than a volt meter is use a 12V test light.
GPR is closet to the windshield on the passernger side. Large post with rubber boot cover is constant 12v's.
Other side gets 12 volts once key is on. If the test light wont light up the gpr is bad. Ground/black lead to truck battery. Red wire lead to bare large post on GPR.
All the screw driver does is jump the 12v from constant side over to other side so it takes the voltage to the glow plugs.
Think of the relay just like a ball valve on a garden hose. If it's closed no water will flow. If GPR is bad the voltage current wont get to the glow plugs.
FWIW just be more patient here. Lots of great teachers here, trying to help you.
GPR is closet to the windshield on the passernger side. Large post with rubber boot cover is constant 12v's.
Other side gets 12 volts once key is on. If the test light wont light up the gpr is bad. Ground/black lead to truck battery. Red wire lead to bare large post on GPR.
All the screw driver does is jump the 12v from constant side over to other side so it takes the voltage to the glow plugs.
Think of the relay just like a ball valve on a garden hose. If it's closed no water will flow. If GPR is bad the voltage current wont get to the glow plugs.
FWIW just be more patient here. Lots of great teachers here, trying to help you.