Thanks for all the advice for finding the electrical issue. I guess I'll have to buy a voltmeter and learn how to use it.

 

Put the amp meter between the disconnected positive lead and the battery. This will tell you how many milliamps the drain is. Next pull each fuse one at a time until you stop the drain. This will give you an idea where to look.

I found an aftermarket anti theft devise that was draining my battery just like yours. Disconnected it and problem solved.

All the usual suspects too. Glove box light, engine compartment light, interior light and door switches.

Also buy a Battery Tender. The cheapest one is all you need. You can plug it into your cig lighter or hard wire it to the battery.

Good luck and keep us posted!

 

I also have a '90 C4 Cab. Welcome to the club

 

Thanks for the info and tips, everyone.

I removed the engine tray and was pleasantly surprised by how dry the engine was. The tray was a grimy mess, but the leaks seem to be mostly on the upper right side. Not a general all over leaky motor. The no-gasket heads seem to be dry.

Do all the vertical pieces of the tray box need to be removed to do a valve adjustment and plug change? I spent some time on my back, and it seems so to me.