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Discussion Starter #1
Did all new motor craft glow plugs with new harness on both sides along with a new injector on hole 5. Drove the truck a total of about 50 miles and on cold start it struggles to fire, usually takes 15 seconds or so to fire and when it does there’s a huge white/black cloud then it clears up. Also smokes white while it’s turning over as well. Checked the codes and nothing which pretty much eliminates the GPCM from what I’ve read. Truck runs great once it fires up and runs for a few seconds. Hot start it fires up flawlessly. Batteries are only a year old and I keep them on a tender. FICM is 48v. Has fresh oil and fresh fuel filters. Any ideas, google isn’t coming up with much.
 

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Can we assume an '03 ...looking at your handle?

What you describe says to me the glow plugs are not working

What are you using to check for codes?

You have been around the forums enough to know what parameters are usually asked for -- posting them would be good
 

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Discussion Starter #3
2003 6.0, I’m using my SCT handheld tuner to run the codes, which I’ve also read sometimes isn’t 100% accurate.
 

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Forscan is the goto tool for codes and checking parameters on the truck -- Torque Pro works well for monitoring

Forscan for PC is a free download and the "lite" version cost is minimal -- there is a list of qualified adaptors on their web site -- some get by wit the cheap knock off ones, but whatever
 

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Discussion Starter #5
Perfect I’m going to look into it. As for the GPCM I read on another site there was a way to measure resistance with a ohm meter on a black/pink striped wire on one connector while the other remained plugged in, not sure exactly how it was worded but something along those lines. Is there any truth to this claim because 99% of everything else I have read says it is pretty black and white with these GPCM, they either throw a code and are bad or they don’t and are fine.
 

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The terminals in the Black(even) and green(odd) connectors can burn

Check this vid -- the info on the late style is about 12:00 minutes

 

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Discussion Starter #7
Thought id post an update. Currently working night shift so I’m a little limited on what I can do but I did unplug the GPCM and tried to start the truck. What I noticed was quite a bit more white smoke while it tried to start but it while cranking you can hear the truck stutter like it wants to fire which did not happen when it was plugged in. When it was plugged in it just turned over until it finally fired up(no sputtering like it was trying to fire). Checked the codes with my SCT (not the best method) to see if it would throw a code with them unplugged and it does not. Tomorrow I’m gonna see if ol autozone can run the codes with any better luck until I get my own code reader set up.
 

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The terminal in the lower right of your picture is the 12 volt power wire for the logic side of the module(need to check power on this wire) - the communication wires are in the green connector -- may suspect a shorted or broken communication wire because of the code P0683 -- but no power to the module would also throw that code

Glad you got Forscan working, it is a very useful tool for these engines - there is a glow plug test that Forscan will do -- I suspect yours will fail - possibly with comm codes

After the test, would be good the check the 12 volt feed to the module and to ohm the wires back to the PCM to see if that is the problem
 

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Discussion Starter #10
Tested the power at the GPCM plugs for power and on the middle left of the picture and had power to both plugs. Tested the lower left like you said and with the key off I got nothing, key on my meter was all over the place couldn’t get a set reading. Test light showed nothing key on or off.

Glow plug test only came back with the same fault, p-0683 along with a u0306.
 

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Tested the power at the GPCM plugs for power and on the middle left of the picture and had power to both plugs. Tested the lower left like you said and with the key off I got nothing, key on my meter was all over the place couldn’t get a set reading. Test light showed nothing key on or off.

Glow plug test only came back with the same fault, p-0683 along with a u0306.
Sounds like a broken 12 volt wire or bad fuse -- I will look at the diagram to see it shows where the 12 volt power comes from
 

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Discussion Starter #12
Ok if worst comes to worst I can follow that wire all the way back but it’s going to suck.
 

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Appears the 12 volt power comes from the same wire as the PCM, Fan, IPR, and EGR use

I found a couple of pin point tests you may find useful
 

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updated the wiring diagram, I had posted a 2005 at first - changed it to the 2003 to better reflect the truck
 

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Discussion Starter #15
So If you follow that 12v power all the way is that the fuse panel it runs to that’s under the steering wheel? If so I doubt that fuse was bad because I should have faults from the other things running for that power as well right?

And on that test it seems to just say to run a glow plug self test and if you get the code p0683 (which I did) to refer to af13. Went to google and tried pulling it up and it wouldn’t let me.
 

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the wire eventually goes to the PCM power relay, and yes there would be trouble with other systems -- if there is power loss on that wire, check at the other locations with your test light to chase it to the broken spot

The AF13 refers to the section in that second pinpoint test .pdf

I personally do not like pinpoint test charts, as they assume one is an idiot and can only follow a prescribed path -- but some can use them effectively
I like to understand how and why a system works -- the flow chart method will get you there but you will not know why the problem is fixed
so like a rat in a maze one runs to the perceived solution

Anyways ...follow the steps in the flow chart -- basically looking for voltage with the key on for the power wire
then a signal from the PCM in the Enable wire
 

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Discussion Starter #17
Ahhh ok, if that pin in the lower right you pointed out should have key on power, I’m assuming the break has to be in between the connector and the junction where it splits off to other areas but we will see tomorrow morning how it looks.
 

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Discussion Starter #18
Used the test light to check the red wire on the lower right of the black plug as far back as I could and had no key on power. Checked every single pin in both connectors and only have power from the pins on each connector that links to the battery. (Big single blade connector) At this point I can only assume the harness is bad somewhere further down the line.
 

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Should have power at the EGR connector, that is the same 12 volt wire -- if you do have power at the EGR - just a short distance to the GPCM, broken wire between there -- I suspect that if you feel along the harness you will find the rubbed spot
 

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Discussion Starter #20
Ok just checked and I have power to the egr connector so I’m pulling all the tape and wire loom from there back and I’ll let you know what i find
 
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