Gauges Acting Weird?

[ronalddragon]

1991 W250
Radio and gauges were working ok, (Except Fuel) But.
We went for a ride in the mountains, Now when in Neutral everything works. as soon as I put the truck in gear the gauges and the radio quit?
Put it in neutral everything works again.


Also, can you buy a complete NEW Wiring Harness?

Thanks

 

[DVolk]

What happens if you shake the truck when in neutral and the truck is running ? how is it charging ?

 

[ekroman]

Check your body ground, from the battery to the body. I had a big problem with instruments not working, and realized the ground wire from the battery - post to the body was disconnected.

You can cheat by connecting a jumper cable from the negative battery post to the body, and see if everything comes back on.