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Engine Wiring Harness

8.5K views 16 replies 3 participants last post by  keithneville13  
#1 ·
I have a 2004 F250 Lariat 6.0 Build date of 5/04 Just reaching 400,000 M. I'm in need of a new wiring harness, tired of just replacing pigtails. Wires are old and brittle. So I can only find two different part numbers to replace this with. One before 9/23/03 part 3C3Z12B637BA and one after 9/23/03 part #4C3Z12B637CA W/O heater. My question here is will part #4C3Z12B637CA W/O heater work on my truck? My truck came with the heated fuel pump which I have replaced along with the upgraded pigtail and now does not have the heater.

Thanks
 
#4 ·
$200 is the aftermarket "god, I hope this works well" version. The OE is around $450.

 
#5 ·
Ford hasn't made these since 2011 for this truck, according to my dealer, and what's the point of salvage yard replacement. Someone else's problem! For the same amount of money. I have my own problem thank you. Just sayin'. I'll try my luck I suppose. I've had some pretty good luck with aftermarket parts thus far. Not always I must say.
 
#6 ·
I would not use a salvaged harness. Occasionally they show up. I've got a brand-new injector harness in my garage from 2008. A cold dead, hands situation. But some dealers are willing to do a nationwide search other than what's at the warehouse or in production. Although, that may be played out by now. I've talked to two people who have bought the Amazon aftermarket HFCM harness with problems.

It would be a PITA, but I would pin out all the locations before putting it in as a precaution.
 
owns 2003 Ford F-350 Lariet
#9 ·
It isn't $200, but they say it is in stock (and I realize that FREQUENTLY these dealerships really are out of what they say they have).



I known you can call ANWBL and ask for internet sales and see if they really do have the part.
 
#10 ·
That's an unfortunate problem lately, developed by the shortages. Ads without product.

The retailer or dealer has no idea when something will return in stock. Even within the Ford product line, items were listed as discontinued; then the Ford mother ship had them again. The bean counters see the demand, then tell the supplier to extend the contract. Tooling may have been broken down, sold, or whatever. Ford owns the tooling suppliers use - part of the contract, which is supposed to be destroyed with evidence when the contract is over.
 
owns 2003 Ford F-350 Lariet
#14 · (Edited)
Looks like the output of Fuse 22 (PCM power fuse in CJB) is the same power that eventually makes it way to the IPR on pin 1 (should be battery voltage). It also feeds the power to the GPCM, EGR, FAN, and others.

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-jokester
 
#15 ·
Okay; After testing fuse 22 has 12v with the key on. After testing pin 1 at the PCM side of the harness to the IPR plug, nothing. I did however, test other pins on the PCM side to see what would happen and low and behold pin 13 goes to the IPR plug. In my pinout chart pin 13 is not used, how could this be, I ask myself. Pin 1 on my chart says Generator/battery charge control; Would be safe to rewire the IPR from pin 13 to pin one in this case? This is an aftermarket harness and no other codes are showing. Thanks
 
#16 ·
I was referring to pin 1 at the IPR connector - sorry...should have been a bit more specific.

As for an aftermarket harness...they SHOULD all be the same, or else things no worry correctly, but we all know that's not always the case. Can't help ya there...

-jokester
 
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