That's what I was thinking tonight after checking everything over again. I need to get into the ignition circuitry next. I pulled the two ground connections (one to the radiator support and one to the engine mount) and cleaned them and verified no resistance. They both test good 0.0 ohms to engine mount and 0.1 ohms to the radiator support, but it'd be great to just get a new set of positive and negative battery cables I suppose.

And good eye on the yellow wire. A mouse got after the yellow wire just at that one bend. Thankfully they didn't chew on any taped together harness wiring, but I notice little spots like that here and there on any single wires that are sticking out. I need to paint them all with liquid tape here shortly.

What sort of voltage or resistance tests should I run against the ignition terminals? And should I unhook any other items when running the tests in order to figure out where a bad resistance section lies?

With key off I'm getting full battery voltage of 12.69v in the case tonight from alternator positive wire to 'top pin' on the regulator which is the red wire. 12.69v is what I measured across the battery posts tonight. My multi meter is some no-name middle of the road Fluke knock off, but seems to have nice test leads on it. I think I got it at Lowes a couple years back. I can tell the voltage is high by how bright the original headlights are. It's great at night, but as SlantSixDan mentioned, it's not correct.

You'll want to fix this, pronto. Make it a priority.

Josh is pointing you in a good direction. Ignition switches and firewall connectors are famous for developing internal resistance.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I found a factory service manual on ebay for 25 bucks and snagged it last week. It showed up Tuesday and is awesome. The Haynes manual is now useless.



The preview to the rest of my potentially useless story is that my voltage reading is now about 14.6VDC on average. A bit lower, but still on the high side of normal. However, it's within spec of what the service manual states. This just happened by nature of me cleaning connectors and fiddling around with the wiring. I didn't specifically do anything to the ignition circuitry.

There are three different voltage regulator tests mentioned in the service manual. Unfortunately many tests in the book require Chrysler tool XXXX to perform the task. Fortunately I don't think I'll need to test anything further relating to the voltage regulator.



But more useful are the wiring diagrams specifically for my truck. I pulled the connectors apart under the dash for the ignition switch and cleaned them with DeOxit. I did the same for the bulkhead connectors. My bulkhead connectors look clean and unburnt (including the ammeter connection) but when I put everything back together the truck randomly doesn't like to run now. It goes into this weird state where it'll idle kind of OK but if you give it any gas it wants to die. Basically ignition related. The fix was to unplug and plug-in the bulkhead connectors. At least I now know what they all are. My plan is to carefully crimp the female spade connectors for the ignition circuits (coil and signal) to see if I can get a more reliable connection to whichever is failing. I cleaned everything with a brass brush and used DeOxit on the connectors. I'm guessing with age they are just a bit loose now that I've disturbed them.

But I think I'm on the right path to getting things running more reliably.

I created a PDF file if any of you ever need to map the bulkhead connectors for a 1974 D/W 100 truck/van. The wires colors in my truck match this document.

Snag it here if you like:
https://drive.google.com/open?id=0B4E1DiRGK3V3MUJ4b3h1blRfS1k

There, fixed it for you.