Does anyone know how to test a GPCM?

 

Thanks to Wood-N-Things I have the circuit diagram and pin breakout. But I have no idea how to test it.

 

Toss in garbage Sorry you have 8 wires coming out of the GPM they go to each glow plug, you should have a red 10ga min. constant battery voltage and a key on power source too. then you should have 2 wires that go to the pcm, to activate the module. If you have your 2 power sources, and you ohmed out each glowplug should be around 5-6 ohms, and the pcm is reading the IAT and the ECT and EOT properly you have a bad module, if more than 3 glowplugs are bad or open it will shut down the module to protect it.

 

If this diagram is right than just ground pin 101 that should turn on the glow plugs, but I dont think that diagram is the same as what you have, that a california model 7.3 from 2000. Always ohm your glow plugs, take your ohm meter and ground 1 lead and test each glow plug with the other, look for around 5 ohms on all 8. or else the pcm wont turn the module on.

 

If the first post shows the control unit you have (California)

If there is any failures that occur it should be logged in the PCM.

 

Thanks Tom & Dave........

Yes, this is the one in my Excursion. The F-250 has the brown cylinder shaped GPR.

Thanks!

 

1FMSU43FXYEE is my vin
2000 excursion 7.3l 4x4 limited.

I have p0677 and p0671 which is glow plug 1 and 7 faults.

I pulled valve covers off both sides and pulled gasket wiring before it got dark.

I found that there is cracked wiring on the engine harness as well as the gasket wiring seemed smashed and cracked. Might have shorted out on head.

I ordered replacement valve cover gaskets from Amazon. But I want to order a replacement engine harness so I can have a fresh wire harness to last hopefully another 20+ years.

the question I have is should I swap the GPCM or just test it. Does this need to be tested in the truck or is there a way to bench test with a multimeter? If so how?

also I’m not sure it’s a California emissions truck. From what I have found during my hunt for information. If it had a GPCM and not dual relays it is a cali truck. I need to check under the truck to see if there is a cat.

im a fan of replacing everything that looks like it could cause problems in the near future. But does any of these aftermarket parts hold any weight. I plan to test the wiring in the valve cover before reinstall. I heard the aftermarket stuff can have issues.

for the engine harness I would hate to swap it all and then have an issue.

any help would greatly be appreciated.

Also this is the only part number i could find

 

First off I would only buy Ford Motorcraft parts or International parts for our engines. Dorman products are just subpar. Also all Excursions had the GPCM, doesn't matter if its a CA model or a FL model. All CA trucks had the GPCM but trucks made for the rest of the 49 states had a Glow Plug Relay.

 

YC3Z12B637BA
This IS your main engine wiring harness part # listed above. I got lucky and found it through my local Ford dealer who helped me by referring me to another dealer in Ohio. My harness was weak and needed more repair than I had time to do. These OEM harnesses are no longer being produced by Ford, but you may still get lucky and find one as I did from a dealer somewhere. If I remember correctly, the dealership that I purchased my harness from was Fairway Ford in Ohio. Good luck!

 

I know there is a small business in New Jersey, I think, that makes any type of harness you need for a vehicle. All you have to do is send them your old harness and they make it to spec and with new connectors. If I remember tonight when I get home to find the website/ phone number and post it on here for ya.

 

Ok I found the place I was talking about that makes wire harness and injection molding. Here is the link, https://www.narragansettreproduction...wiring-harness
They are located in Rhode Island, they're phone number is 401-364-3839

 

an Alternator source:Engine harness vendor



https://swagperformanceparts.com/swa...lifornia-emis/





.

 

Here is the outcome.

1&7 didn’t even ohm out.

the rest tested ok kinda on the higher side.

I put new plugs in and am hooking up the harnesses for valve cover now. I would assume the engine harness is ok and I am going to leave it for now due to cost restraints.

I’ll update if this thing is back on the road this weekend.

Thanks for the help boys

 

I have been fighting With the first one for about 15 min already. Doesn’t seem to want to line up.

 

straight vice grips help a tone. Lol.

firm grip, line em up and press down. Simple once I used my brain. 😂