Another lmtv that won’t start

[ghog50cal]

So I wired the push button open and am getting 24 too the top and bottom of the aux relay on the frame when it’s off there’s no voltage too the top or bottom

 

[Ronmar]

Well voltage down there means the wire is allowing a circuit from K1 to the aux relay, but remember you didnt get a path to ground from K1-87, so I would say the wire from the aux relay to ground is not making a circuit.

on the older trucks they had a thermal sw in the starter that they ran the aux relay connection to ground thru. It plugs into the front of the starter. On starters without the thermal sw, they put a jumper in the plug that would normally plug into the starter. I would look for that plug next to make sure it is either plugged in or jumpered…

 

[ghog50cal]

It’s plugged in too the front of the starter

 

[Ronmar]

Well you need to unplug it and make sure
One side had a circuit to ground and the other side a circuit to the aux relay. If you still have your test jumper on the start button you should see the same 24v you saw on the aux coil wires on one wire into that plug.

then you need to see that the switch inside the starter has a circuit. You can also put a jumper in that plug to simulate the thermal sw and see if the aux relay energizes/starter cranks…

 

[ghog50cal]

So the thermal switch has power when I jump the thermal switch the truck starts right up

there’s jumper wires everywhere lol

I removed the jumper wires from the switch in the cab and hooked it back up too the button with the thermal switch jumped it starts right up

the only thing is I never found the short in the cab other than just moving wires around too get power too k1 so this truck has a gremlin in it

 

[Ronmar]

Cool, at least if it happens again you know exactly how to look for it…

 

[ghog50cal]

Thank you for all your help