Sudden Electrical Failure

[sdelaney]

Hello All,

Yesterday we had a major league micro burst/derecho/tornado around here. Winds pulling trees out by the roots, horizontal rain (ALOT) and so forth. Lasted about 30 minutes.

When it was over I got in my 83 C20 (c code) and it started right up as normal (manual glow plugs) and drove over to a buddy's house to help out (they got hit worse than me). As I was pulling out of my driveway some water that accumulated on my tonneau cover spilled forward between the cab and the bed.

I drove about 5 miles without issue and parked. After being there about an hour I tried to start up but it wouldn't catch. It wasn't like it was ALMOST catching, it was just cranking over and not starting. So as to not wear down the batteries I just let it sit for another half hour.

When I tried to start it again there was no power to anything whatsoever. Completely dead.

Both batteries are showing 12.55 volts on the tester.

Both batteries are brand new last August.

New gear reduction starter last November.

Where do I start chasing down this problem?

Thanks

[JohnC]

Measure from a ground to the battery. If you get 12.55 volts there, start marching the positive probe down the positive lead off the batteries until you find the point where the power disappears.

[sdelaney]

Measure from a ground to the battery. If you get 12.55 volts there, start marching the positive probe down the positive lead off the batteries until you find the point where the power disappears.

Okay, thanks.

I started from the passenger side battery down to the starter (12.49v at starter) and sort of fiddled with the other connections on the starter.

Tested it by turning the ignition to the ON position - nothing.

For the hell of it I tried the ACCESSORY position - the glow plugs, wiper, radio, and cigarette lighter worked, but all stopped if I turned on the headlights.

Then I tried the ON position again and everything works as it should. Started right up too.

I'm not a big fan of mysteries when it comes to automotive electrical, so what the hell was that all about?

[DmaxMaverick]

Sounds like you have a breaking load connection, likely either the battery terminals (very common) or the starter solenoid lug (big pole). Showing voltage or not isn't much help with no load, when the problem is with a load. Remove, clean and reinstall with some dielectric grease.

[JohnC]

Either that, or your ignition switch is about to give up the ghost.