Electrical confusion

[Sam27]

Here's the story: I have a 86 CUCV with a civilian glow plug conversion. I went out to start the truck - I turned the key, saw the "wait" light, waited a little while and turned the key to start. At that point, some sort of click or pop or something (not loud) and no start. At that point, the wait light would not come on and the truck wouldn't start. It was like the glow plug controller and the starting system both were messed up.

So I checked all the fuses, checked battery voltage and checked power to the glow plug controller. All good. I connected my meter across the 12V battery and watched it as I turned the key to on (glow plug position) it dropped WAY off, like to 11 volts, even though the "wait" light did not come on.

Finally, I put the battery charger on the front battery. It fired right up, but the "wait" light still never came on. I'm pretty sure I could hear the clicking of the glow plug relay though. I drove the truck for a little while (20-30 minutes) and shut it off. After that, it fired right up, but still not "wait".

I checked the "wait" bulb and it's good.

So, long story, but any idea what is going on? Maybe the glow plug controller is messed up, but why would that cause the truck not to start? Maybe the battery is fried, but then why no "wait" when the charger was on it? Any ideas?

 

[CUCV850]

have the batteries tested under load, bad battery can show 12v with a volt meter.

 

[Sam27]

I had the front battery (the one I jumped) tested and it came out okay. So it's all kind of a mystery still. I'm going t put it back in and I bet it will work right except for the wait light. I guess next I'll try to find out if the glow plugs are actually getting voltage or not.