1994 Powerstroke GP issues
Thread Starter
|
Junior User
Joined: Oct 2011
Posts: 63
Likes: 0
1994 Powerstroke GP issues
Replaced all 8 GP's, the GP unit itself, checked all fuses. The glow plugs are still not working. Checked the GP unit power is not getting across when the key is on. Is there any fuses I'm missing? How about the relays inside the engine bay fuse box, what are they for? Any help is greatly appreciated
Posting Guru
Joined: Dec 2008
Posts: 2,347
Likes: 1
From: Maysville, Kentucky
I assume your calling the gp unit the relay? Take your relay in top of the motor and apply twelve volt to the very small post. This should make the relay function with just a click. If that doesn't work then the relay is bad or wrong for the application.
Where did you get it and what part number. What brand and part number gp's did you use as well? The pcm supply low amp power to control the relay but I don't remember 100% if its fuse linked.
Where did you get it and what part number. What brand and part number gp's did you use as well? The pcm supply low amp power to control the relay but I don't remember 100% if its fuse linked.
Postmaster
Joined: Sep 2007
Posts: 4,195
Likes: 6
From: Medford Oregon
Fuse #22 supplies power to the GPR coil.
Does the WTS light work ... if so then fuse #22 is OK?
The 1 big wire on one of the big lugs should be hot or ~ 12 volts all the time. It is protected by a fuse link located near the starter relay where this 1 big wire connects to. The other big lug should be hot or ~ 12 volts when key is ON (relay pulled in). The two smaller wires control the coil of the relay ...
One of the smaller wires is hot or ~12 volts with key ON. The other smaller wire is pulled to ground by the PCM to activate the relay coil.
Try this ... disconnect both smaller wires. Jumper one of the smaller relay lugs to battery plus and jumper the other smaller relay lug to a ground. The relay should pull in and you should hear a click. If so the relay is working.
Here is a diagram ...
Does the WTS light work ... if so then fuse #22 is OK?
The 1 big wire on one of the big lugs should be hot or ~ 12 volts all the time. It is protected by a fuse link located near the starter relay where this 1 big wire connects to. The other big lug should be hot or ~ 12 volts when key is ON (relay pulled in). The two smaller wires control the coil of the relay ...
One of the smaller wires is hot or ~12 volts with key ON. The other smaller wire is pulled to ground by the PCM to activate the relay coil.
Try this ... disconnect both smaller wires. Jumper one of the smaller relay lugs to battery plus and jumper the other smaller relay lug to a ground. The relay should pull in and you should hear a click. If so the relay is working.
Here is a diagram ...
Posting Guru
Joined: Dec 2008
Posts: 2,347
Likes: 1
From: Maysville, Kentucky
Run a jumper wire and see if there is power to the other side of the relay. Make sure that the system is working then start tracing back.
Trending Topics
Elder User
Joined: Aug 2009
Posts: 869
Likes: 1
From: Michigan
had to go copy and paste this from another similar post:
the best way I have found to check the gpr is to test it with a cold engine and a volt meter. turn the key on and check the 2 small posts of the gpr if you have 12 volts there that means the relay is in fact on. now that you know for sure the gpr is on, check the volts across the 2 large terminals. with the relay on there should be 0 volts or a very small fraction of 1. any reading you get during this test is the amount of volts that are NOT getting to the glow plugs. any significant reading and I would place my order for a new GPR.
the best way I have found to check the gpr is to test it with a cold engine and a volt meter. turn the key on and check the 2 small posts of the gpr if you have 12 volts there that means the relay is in fact on. now that you know for sure the gpr is on, check the volts across the 2 large terminals. with the relay on there should be 0 volts or a very small fraction of 1. any reading you get during this test is the amount of volts that are NOT getting to the glow plugs. any significant reading and I would place my order for a new GPR.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Thread Starter
|
Junior User
Joined: Oct 2011
Posts: 63
Likes: 0
Thanks for all the great responses! Another issue I have is my engine is missing so I know I have atleast 1 injector out. Is there anyway to check without pulling them? Maybe a laser heat gun on the exhaust manifold at each?
Postmaster
Joined: Sep 2007
Posts: 4,195
Likes: 6
From: Medford Oregon
Think you found your problem on GPR. The Red/Lt Grn wire should be hot with key on. Nothing magic about it, it's just a wire that goes from the small bolt you mentioned, through the 42 pin connector to fuse #22. Since the truck runs we know fuse #22 is OK so it's somewhere in-between.
Postmaster
Joined: Sep 2007
Posts: 4,195
Likes: 6
From: Medford Oregon
No, fuse #22 30A protects it. Refer to the diagram above and you can see where connector B on the GPR goes thru the 42 pin connector - pin 35 - then to a fuse. That is fuse #22. From you observations a wire is broken somewhere along the route or maybe bad connection to the underside of the fuse block.
Note: I did get your PM and will see if I can send you a better diagram on e-mail. Might have to wait until tomorrow until I'm on another computer and can do some PDF conversions.
Note: I did get your PM and will see if I can send you a better diagram on e-mail. Might have to wait until tomorrow until I'm on another computer and can do some PDF conversions.
