2003 6.8 no start problem

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Jul 1, 2012 | 07:19 PM

mason34racer

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2003 6.8 no start problem

Hey guys, just found this forum and wanted to see if you guys could help trouble shoot a problem with me. I have a 2003 f250 6.8 that died coming home yesterday. Found that fuse # 116 was blown (large pink 30A fuse) put a new one in and it blows it as soon as you turn the key to the ON position. I pulled a COP and plug and have no fire. Not sure what all this fuse powers or where to trace wires to for any chaffing. Thanks in advance for any ideas.

Jul 1, 2012 | 08:14 PM

jh818

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From: Chino, California

Try inside your steering column on top near the shifter. It's a common location on the SD trucks and Expeditions. May not be your problem, but you could check. Good luck.

Jul 1, 2012 | 09:04 PM

mason34racer

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Okay, just took steering column cover off and checked wiring inside. I didn't see any chaffing and took the electrical tape off the wires to see if anything could have worked loose but everything looked good. Even "wiggled the wires" to see if anything changed on the multimeter but no luck. But I did see the way the wires were in there and I see what you're saying about that being a trouble spot and thanks for the reply. Is there any other potential troble spots that you can think of? Thanks

Jul 2, 2012 | 08:56 AM

krewat

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Check your owner's manual and see what that fuse supplies. It's probably the red wire going to the COPs and injectors, and even possibly the O2 sensor heaters.

You might have a chafed wire under the hood, and it's shorting to ground. The PCM wouldn't throw enough current into a COP to blow that fuse, so I suspect that the red wire in the harness is shorted somewhere.

Jul 2, 2012 | 01:50 PM

projectSHO89

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Wrong fuse for the wiring harness problem at the shifter.

Jul 2, 2012 | 03:16 PM

mason34racer

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Ok good news and bad news... I've found the short. It was in the engine compartment where the wiring harness comes through the firewall and a bracket that holds the mass of wires and a few relays. The mass of wires were bent around the bracket and rubbed through. Got that fixed and truck runs again but the new problem is it will not cut off. (Yeah I know its one extreme to the other, LOL) Can't find any other wires that are chaffed, could something be shorted out or should I be looking for another wire. It will run even with the key out of it And I can cut it off by taking the fuse out but as soon as you put the fuse back in all the dash lights come on like the key stays in the on position.

Jul 3, 2012 | 08:11 AM

krewat

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Sounds like something else is shorted. Unplug the ignition key harness and see if it still does this, then work your way backward.

There could be a relay stuck closed, it could have welded it's contacts together when it originally shorted to ground and blew the fuse...