Electrical issue got me stumped...

[CSIPSD]

Got an issue I cant figure out...

Drove from Bend Oregon to Phoenix Saturday. About 3/4 of the way down here I noticed my volts gauge was reading 13v or so. Not a big deal, drove non stop, figured the regulator was just hot.

Sunday night on the way to the jobsite I noticed it was now at 12v...

Ok, lost another Alt, not the end of the world, I average about one a year or so. Lifetime warranty from Napa, 30 minutes to swap and your on your way.

New alt in, no charge. Check all the fuses, nothing blown, replace all the fuses anyway and still nothing.

Found the fuseable links at the starter solenoid were cooked. Replaced with a MAX fuse holder and a 30 amp fuse. Start truck, starts charging for a few seconds and nothing. Replace 30 amp fuse with a 60 (I dont know the rating for the factory fuseable links so...) Worked, but the wire harness gets HOT, so I know I have a short there somewhere.

I am in AZ, 1300 miles from home, so I dont have all my tools, sitting in the NAPA parking lot trying to figure it out...

Bandaid for now, a battery cable from the output of the ALT, to the drivers side battery. Not right, not safe, but it keeps me going from the hotel to the jobsite.

Anyone ever run into this issue?

 

[ja_cain]

You know I have been thinking about this kind of thing lately. What kind of phone do you have? I have been thinking about getting one of the add on thermal cameras for my phone so I can troubleshoot problems just like this. You should be able to scan the harness wires after running it for a minute or two. Needs to set overnight so it can cool completely as this will give you enough contrast/temp differential to pick up on a wire that is drawing too much current. Make sure you do it when the ambient temp is high enough not to call for the gp's (not sure what that is) or just ignore any wires associated with that circuit unless it is suspect. Electrical problems suck, that's why I bought an O-Scope and clamp meter at work. Just need to get some kind of thermal camera device and then I will be set. Good luck!

 

[Tom S]

Stuck glow plug relay maybe?

 

[IHPowerstroke7.3]

Try another Alternator? Put a rebuilt one in a friends 7.3 for him after his died. After 20 mins of idling, the alternator case got so hot I couldn't touch it. Swapped in another and it was fine.

 

[Dzchey21]

My guess is the starter is shorted out.

Doesn't the ecm control the out out of the alternator on them?

 

[CSIPSD]

Starter seems fine. It starts great.

Glow plugs I disconnected and it still did it.

 

[Dzchey21]

I have seen them draw but start fine. Does the batteries run dead after sitting? You need to throw an amp clamp on it and see how many amps is being pulled as well as voltage charging.

 

[Dieselwrench]

For what it's worth I had a 7.3 that ate alternators like candy. I finally traced it down the two female connections from the engine harness to the alternator. The connection would make and break while driving causing the alternator to switch off and on. That switching power not only caused the alternator to crap out quickly, but it made it extremely hot while running. Now I don't think that would cause your dead short problem, but it might keep your alternator happy.

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[Jomax]

What kind of tools would you need?

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[Arisley]

Got an issue I cant figure out...

Drove from Bend Oregon to Phoenix Saturday. About 3/4 of the way down here I noticed my volts gauge was reading 13v or so. Not a big deal, drove non stop, figured the regulator was just hot.

Sunday night on the way to the jobsite I noticed it was now at 12v...

Ok, lost another Alt, not the end of the world, I average about one a year or so. Lifetime warranty from Napa, 30 minutes to swap and your on your way.

New alt in, no charge. Check all the fuses, nothing blown, replace all the fuses anyway and still nothing.

Found the fuseable links at the starter solenoid were cooked. Replaced with a MAX fuse holder and a 30 amp fuse. Start truck, starts charging for a few seconds and nothing. Replace 30 amp fuse with a 60 (I dont know the rating for the factory fuseable links so...) Worked, but the wire harness gets HOT, so I know I have a short there somewhere.

I am in AZ, 1300 miles from home, so I dont have all my tools, sitting in the NAPA parking lot trying to figure it out...

Bandaid for now, a battery cable from the output of the ALT, to the drivers side battery. Not right, not safe, but it keeps me going from the hotel to the jobsite.

Anyone ever run into this issue?

Try a 40 amp fuse Joe. Number sticks in my head for some reason.

What kind of tools would you need?

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And there ya go.

Good luck Joe. Let me know if I can help. If I had the wiring book, I would trace down the rating for that fuse for ya.

 

[Dieselwrench]

Call me stupid, but tools for what?

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[mandkole]

Call me stupid, but tools for what?

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in Joes first post, he noted that he wanted more tools. Im sure diagnostic stuff.. dealing with difficult to diagnose electrical stuff on the road would suck.

 

[CSIPSD]

I think at this point I want to replace the whole top of motor harness...

 

[Dieselwrench]

Ah, I got you. A simple code reader and a multimeter would get you a long way.

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[Jomax]

Joe, if you need a multi reader or AE. Or any tool for that matter. Lemme know.

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[Jomax]

I think at this point I want to replace the whole top of motor harness...

I have some guys that might be able to get you one used.

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[CSIPSD]

I have AE, but there are no codes for this. Its a dead short somewhere, somewhere unfused as it killed the fuseable link.

 

[Jomax]

Found one. Harness came off a 99. Truck was working but was a rollover.

$100 for the harness.

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[NC714]

Did you Double check the power wires from the AIH ****** to make sure they aren't shorted anywhere?? Did you remove the AIH relay?

 

[CSIPSD]

Did you Double check the power wires from the AIH ****** to make sure they aren't shorted anywhere?? Did you remove the AIH relay?

There cut off and tucked into the harness. I need to pull the harness open and see if it is, but I doubt it.