Hello all. The IGN light in the dash cluster on my '65 320 has recently come on and doesn't extinguish. I've scoured the service manuals and can't find any troubleshooting information for the IGN light. What exactly does it indicate and how should I go about starting to troubleshoot why it's on? Any advice is appreciated.

It’s an indication that your battery is not being charged. Others will suggest how to trace the problem.

My understanding is that the 320's all had generators (not alternators) and some of the early ones were positive ground. The net seems to indicate almost everyone converts them to negative ground, and converting them to either a 411 or 720 alternator is popular. So what could be wrong with yours depends on specifics, whether it's box-stock and if not, what alterations were done. Presuming your battery connections are all good, if it's a generator you can do a quick charging test with a simple bulb-type test lamp. With the truck running, connect it between the generator output terminal and the battery (plus terminal if you're negative-ground, minus if you're positive ground). The lamp shouldn't light. If it does, the generator is sucking juice instead of producing it.

This is a pretty good treatise on checking generator systems:

www.howacarworks.com/electrical-systems ... ing-output