2004 Engine Wire Harness
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Cargo Master
Joined: Jan 2005
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2004 Engine Wire Harness
Good morning, been a long time since my last post. I think a have a no crank issue from some broken wires. I'm looking into replacing my whole harness. The part number I have found is 3c3z12b637ba. does anybody know what all this harness consist of? I can find individual pigtails for sensors, egr value etc. I cant tell if if there is any not included in this harness. By pictures it looks like the injectors and sensors are included. TIA
Fleet Owner
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Welcome back, but sorry for the circumstances!
Which '04 do you have?
Where is your ICP sensor located?
Which orientation is the GPCM in (vertical or horizontal)?
Also - sometimes no-cranks are related to the secondary engine harness.
Which '04 do you have?
Where is your ICP sensor located?
Which orientation is the GPCM in (vertical or horizontal)?
Also - sometimes no-cranks are related to the secondary engine harness.
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Cargo Master
Joined: Jan 2005
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Thanks, glad to see you still around. I cant complain my truck has over 300,000 miles.
The ICP is up front side of valve cover. I don't remember what direction the GPCM is turned. I'm not at my truck I'll go look in a bit.
My son is driving this truck currently. We just replaced the fan clutch last week. Yesterday he said the last power, he limped to side of road and called me.
When I got there i pulled the codes on the CTS and there was a whole list. CPS, cam sensor, fan clutch speed, system test not completed a couple others. They all seemed commucation in nature to me.
What is on secondary engine harness?
The ICP is up front side of valve cover. I don't remember what direction the GPCM is turned. I'm not at my truck I'll go look in a bit.
My son is driving this truck currently. We just replaced the fan clutch last week. Yesterday he said the last power, he limped to side of road and called me.
When I got there i pulled the codes on the CTS and there was a whole list. CPS, cam sensor, fan clutch speed, system test not completed a couple others. They all seemed commucation in nature to me.
What is on secondary engine harness?
Fleet Owner
Joined: Nov 2003
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The secondary engine harness should contain: the BJB, the Cowling Wiring Tray over the turbo and one end of C1010 MALE, C145 FEMALE, C146 FEMALE, AND the MALE end of C1282 (the MAIN engine harness contains the other end), and the BJB connector.
Sometimes C1282 is damaged if work has been done requiring its removal and re-installation ....... or coolant leaks onto it and damages it.
Sometimes a no-communication issue can be because fuse #22 is blown. Often times this fuse is blown because of a short in the fan clutch or the fan clutch wiring.
Sometimes C1282 is damaged if work has been done requiring its removal and re-installation ....... or coolant leaks onto it and damages it.
Sometimes a no-communication issue can be because fuse #22 is blown. Often times this fuse is blown because of a short in the fan clutch or the fan clutch wiring.
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Cargo Master
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Thx for that info. My GPCM is horizontal. The ICP, IPR, FICM voltage, and sync all look good on crank. No start. There is a new issue and could be caused by my son. I cranked a couple turns to watch the fore mentioned parameters and the engine bay got a nice diesel shower. Now I have to trace down a Diesel geyser. 😒
Fleet Owner
Joined: Nov 2003
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The main engine harness (corresponds to the part number you posted with base part number 12B637) contains:
Your main engine harness is 4C3Z-12B637-AA.Again - Sorry I do not have a more SPECIFIC list of all it connects to.
As stated earlier, the secondary engine harness (base part number 12A581) has the MAP, MAT (IAT2) and MAF connectors and A/C clutch. It also contains the important sensors and actuators that are under the dash inside the cab. Yours is 4C3Z-12A581-AH
There is a separate injector harness (base part number 9D930) from the FICM to the injectors. Yours is part number 4C3Z-9D930-AA.
Specifically, what are you needing?
- the major engine sensors (except MAP, MAT, MAF, A/C, and injector connectors)
- GPCM connectors
- fan clutch
- the C1388C FICM connector
- ICP and IPR
- Alternator control
- VGT actuator and EBP sensor
- EGR
- CAN communication lines
- CKP and CMP
- EOT and ECT
- the FEMALE end of C1282 (the secondary engine harness contains the other end)
other connectors that I haven't documented such as to 4wd control module, A/C, etc.
Your main engine harness is 4C3Z-12B637-AA.
As stated earlier, the secondary engine harness (base part number 12A581) has the MAP, MAT (IAT2) and MAF connectors and A/C clutch. It also contains the important sensors and actuators that are under the dash inside the cab. Yours is 4C3Z-12A581-AH
There is a separate injector harness (base part number 9D930) from the FICM to the injectors. Yours is part number 4C3Z-9D930-AA.
Specifically, what are you needing?
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Cargo Master
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bismic thanks for the information. I haven't had time to trace my harness. Been crazy divided. Yesterday afternoon the diesel shower is coming from a cracked fuel filter cap. I'm gonna replace it today. I'm hoping over the weekend I will be able to remove the top components off the engine and trace the harness down.
Your information was very helpful. At least now I know the main harness doesn't include the injector harness. The picture of the part number listed looked like the injectors wire might be on it but wasnt a good enough picture to tell. You've given me a lot picture of what I'm going be looking through. I hadn't even Thought about the 4wd pigtail. lol
Your information was very helpful. At least now I know the main harness doesn't include the injector harness. The picture of the part number listed looked like the injectors wire might be on it but wasnt a good enough picture to tell. You've given me a lot picture of what I'm going be looking through. I hadn't even Thought about the 4wd pigtail. lol
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Fleet Owner
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Let me correct myself (my apologies for going by memory, lol) - it is the secondary engine harness (12A581) that goes to the 4WD control module and the A/C. Also, that secondary engine harness actually ends in "mid-harness" connector C145 before going to the 4WD control module.
Also - I edited the earlier post to add more detail on the list of sensors that are on the main engine harness, etc.
Also - I edited the earlier post to add more detail on the list of sensors that are on the main engine harness, etc.
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Cargo Master
Joined: Jan 2005
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Cool thx bismic. Just crawled out from under the truck the crank position sensor is definitely chewed up, some sheathing melted. Will a broke crank sensor keep the truck from starting? I'm assuming if the pcm doesn't get a position of the crank it won't command the injectors to fire?
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Cargo Master
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My truck has build date of Nov 03 if I understand correctly you say the engine harness for that build is 4C3Z-12B637-AA.
I think replacing the whole harness will be easier, the egr valve wires are broken as well.
I think replacing the whole harness will be easier, the egr valve wires are broken as well.
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