1985 M1008 won't shut off, but it's not what you think!

[Comeaud]

Hello all.

So my 1985 m1008 has a very peculiar problem. It will selectively not shut off. To complicate matters the engine will not shut off when the parking lights or headlights are on. As soon as you push the headlight switch in the engine shuts off.

In addition to this issue, there are instances where all of the sudden NONE of the lights will work. When this happens the engine shut off issue still occurs. Also, when the parking lights are on and the truck will not shut off, when you move the key to the off position the seat belt light, one of the turn signals, and the low coolant light start to glow.

The lighting issue is obviously frustrating and I can't seem to narrow it down. I have replaced the rocker switch for the signals and wipers because I had a wiper issue as well but it seems to have gone away, the black out switches as I have been told they are a common fail point, and I am about to swap out the headlight switch.

I feel like it is going to be a wiring or ground issue but I want to eliminate the components as being a problem as well. I am definitely not a strong electrician so if anyone has some insight I will gladly take it!

Thanks!

 

[PJL]

Ground problem. Look at the battery to engine and body connections.

 

[Warthog]

Check the ground connections from the harness to the radiator support above the headlights. Also check the main ground connection for the instrument cluster. It is the six legged connector above the parking brake.

Oh heck, just check them all.

There are multiple threads for electrical issues in the CUCV Helpful Threads sticky. Also some pictures.

 

[PJL]

The negative side bus bar on your firewall would be the best place to start.

 

[MarcusOReallyus]

Oh heck, just check them all.

Can't argue with that!

 

[Tinstar]

When you do check them, use some good electrical grease to maintain a good ground.

When I did mine I used NO-OX-ID electrical grease. It actually fights corrosion.
Amazing what a difference good grounds make.
Worth every minute checking, cleaning, greasing ALL the grounds.

Some gremlins disappeared when I was done.

 

[PUNCHYOURFACE]

Definitely sounds like a ground problem, my brother replaced his taillights in his '09 Silverado with LED ones and sometimes the right blinker faintly comes on when you turn on the left blinker.