Head lights shorting to ignition! Help
 

Title pretty much says it all. My 91/93 4x4 keeps shutting off randomly when I turn the headlights or turn signals on. It doesn't happen all the time, but when it does it doesn't always restart right away. When the engine is off and i mess around with the light switch enough I can hear the main plug wire sparking in the distributor. When this happens the temp gauge also shoots up to the top, even though the engine is no where near overheating.

Does anyone have any idea where to start looking for a short or broken relay of some sort? The guy that had the truck before me put a 93 22re in it and didn't do the greatest job wiring it back up. I'm thinking about just getting a shop to redo all of it but if anyone has any ideas that would be great. Thanks!

Nik

I would look at the grounds. That is how the head lights are turned on, they have constant power and then the head light switch turns on the desired low or high beam by grounding it. So it could be the ground connection in the cab is bad and with the high headlight current, you get a voltage loss on the ground side. Cab ground is typically on the driver's side, behind the kick panel, screw into the sheet metal with a bunch of wires attached. Remove screw, clean and inspect all the wire terminals and then reinstall and test. You could also check for voltage differences at the various ground points relative to the battery "-" terminal.

Thanks, That ground, with two little brown wires appears to be good, unless its higher up in the system. What other grounds should there be from the negative terminal. there is only one from the battery to the engine block.

Can't just look at a ground connection, need to pull it apart, clean the connections (wire brush or sand paper - including removing paint from the sheet metal contact) and also check the wires for stiffness, that can indicate corrosion up under the insulation, or even if the wire is broken under the insulation.

Lots of grounds around the engine, battery-fender-block plus head to firewall, intake to block, etc. You can check the grounds as mentioned earlier with a voltmeter, one probe on battery "-" terminal and other probe on head/block/etc. (i.e. anything that should be grounded) and if you see any voltage reading when you start the engine (other than 0.0 volts) there is a grounding issue.

Ok, i'll give that one a good cleaning and do all the others as well. I guess its time to invest in a voltmeter. Thanks for the advice man. I'll let you know how it goes.

Im thinking you have short somewhere, but here is a good diagram of the grounds if that will help. If you go to the first post in my build thread, it will show where it is listed, I show how to get the headlight switch assembly apart if you want to check that also.

https://www.yotatech.com/forums/f116...-guide-194413/

I cleaned up that ground and its been flawless eversince. Thanks guys!