Matt Saunoras Posted January 31, 2014 Share Posted January 31, 2014 04 lists two main engine harnesses. 4C3Z-12B637-AA and 4C3Z-12B637-CA and other than the damn parts description I'm unsure which is which. From what I saw today CA is listed as "without a fuel heater" and AA is "with a fuel heater" I have no idea why it would matter or which harness to order. All I know is CA is lists for much more than AA. The only difference I have noticed over the years is the length in glowplug harnesses. I have seen 04s with real short glow plug harnesses and the one I'm working on has long ones that connect like an 05+ Anyone know anything? My part guy is useless. And also this truck does not have a fuel heater but I have no f-ing idea if it ever did have one. Quote Link to comment Share on other sites More sharing options...
Aaron Posted January 31, 2014 Share Posted January 31, 2014 Early and late ICP location? Quote Link to comment Share on other sites More sharing options...
Matt Saunoras Posted January 31, 2014 Author Share Posted January 31, 2014 Nope these are both late harnesses. The early is a 3C3Z Quote Link to comment Share on other sites More sharing options...
mchan68 Posted January 31, 2014 Share Posted January 31, 2014 If you find yourself needing to order up an engine harness or glow plug harnesses, I have determined the easiest way to identify whether you have a mid/late build, or late/late build 2004 engine. For starters, if your build date is earlier than September 29th, 2003, you should consider yourself the owner of a 2003 truck, when it comes to ordering any and all engine parts.However, those of you with trucks with build dates after September 29th, 2003, things can get a little tricky when it comes to determining the correct engine harness and glow plug harnesses. Here is how to do it. Look at your ICP sensor on the passenger side valve cover. Pay attention to how the GPCM is bolted up to the bracket that secures to the valve cover. If you happen to have it secured in a manner similar to a 2003 engine, you have a mid/late build 2004 engine. As such, your engine uses engine harness Ford part number 4C3Z-12B637-AA (Navistar ID# 1844262C93), to be used with glow plug harnesses part numbers 4C3Z-12A690-AA (Navistar ID# 1845915 C9) right side, and 4C3Z-12A690-BA (Navistar ID# 1845793 C9) left side.If you have your GPCM mounted on the bracket, identically to the way it is on 2005 and later engines, you have a late/late build 2004 engine. As such, your engine uses engine harness Ford part number 4C3Z-12B637-CA (Navistar ID# 1846377C92), and glow plug harness Ford part numbers 4C2Z-12A690-AB (Navistar ID# 1845794 C9) right side, and 4C2Z-12A690-BA (Navistar ID# 1845695 C9). Notice, the right side glow plug harness part number is also identical to that, that is used on '05 and later engines. 2 Quote Link to comment Share on other sites More sharing options...
mchan68 Posted January 31, 2014 Share Posted January 31, 2014 Nope these are both late harnesses. The early is a 3C3Z 3C3Z-12B637-BA to be exact. Quote Link to comment Share on other sites More sharing options...
Matt Saunoras Posted January 31, 2014 Author Share Posted January 31, 2014 Thanks Mike. I've noticed the subtle differences over the years but never paid enough attention. This is the first late 04 I've needed a harness on. I do infact have a late, late 04. I got lucky, CA is the harness I ordered and it is correct. Thanks for the info. Quote Link to comment Share on other sites More sharing options...
Matt Saunoras Posted January 31, 2014 Author Share Posted January 31, 2014 Harness fixed it. This truck had the crank sensor wiring zip tied to an A/C line and it got sucked into the belt. I couldn't see exactly where the problem was but I had to assume it was there. The truck would sit and idle fine one minute and start violently surging the next. Quote Link to comment Share on other sites More sharing options...
Brad Clayton Posted January 31, 2014 Share Posted January 31, 2014 Mike, if the mechanic thing doesn't work out, we could always use a good parts guy down here. Quote Link to comment Share on other sites More sharing options...
Matt Saunoras Posted November 8, 2016 Author Share Posted November 8, 2016 Got another one here I had to dig this thread out for. Someone did headgaskets and jammed the main harness down in between the front cover and left head. The ignition power to the ficm torched the whole wire from the short all the way to the body connector. Never blew the fuse or hurt any other wiring. Quote Link to comment Share on other sites More sharing options...
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