Starter relay question

Truck was running great up to a few days ago, open the door an noticed the smell of burn plastic. It seems I have a short in the 24v hot wire leaving the K1 Starter relay. The insulation on the wire before and after the relay has melted in a few areas. I can’t see any more of the wire due to tape wrapped but the entire wire run, to it destination, should be replaced, BUT, I’m not exactly sure where the wire goes too? So the question is wire does this wire go too? When I find the other end, I can see if that might be the problem or if it is something more. Thank you

https://www.steelsoldiers.com/showt...ker-Lamp-Relay-Gets-Hot-when-I-turn-on-lights

https://www.steelsoldiers.com/showthread.php?190283-FMTV-Anti-Theft-starter-relocation

I just has some issues with relays and my starter button not working. Read the top thread first and then the second if you like the idea. But my guess is a relay is stuck in the contacted position. Relays can have the plastic cover broke off at the seam, it pops back on, and take a look. I had to push my starter relay over to have it come in contact so it would start the truck. I bypassed it. But my guess is, if you replace all the relays and breakers, it would work wonders on the electrical system and prevent future problems. Everything mechanical has a working life. relays and breakers get weak.

Good luck.

The wire diagrams, air and hydraulic layouts are in the back of TM-9-2320-366-20-4

Current flows from X1 to pin 30 on K1. When energized(cranking), K1-30 connects to K1-87. K1-87 connects down to the aux start relay coil on the drivers frame rail just outboard of the starter. The other side of the aux start relay coil connects to ground...

Ronmar said:

Current flows from X1 to pin 30 on K1. When energized(cranking), K1-30 connects to K1-87. K1-87 connects down to the aux start relay coil on the drivers frame rail just outboard of the starter. The other side of the aux start relay coil connects to ground...

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Thank you, exactly what I needed. Now to replace the whole run from X1 to aux starter relay,,, but I better be sure it is not the relay that caused the short(?),,, or maybe the starter(?). At first I thought the wire’s insulation between k1 87 and aux relay got rubbed off and contacted metal but thinking now it might be the aux relay or starter itself.

PFH said:

Thank you, exactly what I needed. Now to replace the whole run from X1 to aux starter relay,,, but I better be sure it is not the relay that caused the short(?),,, or maybe the starter(?). At first I thought the wire’s insulation between k1 87 and aux relay got rubbed off and contacted metal but thinking now it might be the aux relay or starter itself.

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You need to examine the wire down to the aux start relay. Pretty sure K1 couldn't cause this, but a short to ground down at the aux relay could. In a perfect world, enough current to melt insulation would pop a circuit breaker for the circuit, that is why they are there afterall. I would look into the supply CB for the circuit. I dont really like the ones chosen for the LMTV. I replaced all mine with standard auto blade fuses...

Ronmar said:

You need to examine the wire down to the aux start relay. Pretty sure K1 couldn't cause this, but a short to ground down at the aux relay could. In a perfect world, enough current to melt insulation would pop a circuit breaker for the circuit, that is why they are there afterall. I would look into the supply CB for the circuit. I dont really like the ones chosen for the LMTV. I replaced all mine with standard auto blade fuses...

Click to expand...

I was thinking the same. One of the first things I did in this situation was to swap out all the cb with blade fuses, one less thing to trouble shoot. It seems it was the wire from k1 to the aux relay. The relay and starter tested good, but that wire, disconnected at both ends, shows the wire is grounded from both ends. So it’s either in contact with body or frame metal, or it melted through another wire creating the ground. That’s as far as I got before the afternoon rain.

Sounds like you are all over it then, probably chafed thru and contacting the frame somewhere. Good luck!