I've been racking my brain trying to think of anything else I missed. As I mentioned, the engine and wire harness all came out of the same vehicle, and from the best I can tell, everything is back where it was previously. But just this morning something popped into my head when I was trying to figure out what I have changed as I swapped it over, and I can't believe I left this out of my posts. I really, really hope this isn't the issue (well I do because it would fix it, but I don't want to feel so stupid for overlooking it).
When I disassembled the old Jeep I removed the A/C system. It was not functioning properly, the coolant was gone, and with my plans to never have the top and doors on this, there's no point in keeping it. I am going to change the compressor over to an OBA system in time. For now the wire harness that plugged into the AC accumulator at the firewall is not plugged into anything. The wire harness at the compressor is still plugged in.
I don't think that's an issue, but wanted to throw that out there just in case it sparks any ideas. From looking at the schematics, I don't think there's anything in the accumulator harness that would cause this.
I don't think that would cause a problem, but I haven't looked at the schematics for that.
So if the ohms across the entire path are 0.4 ohms, that's not a bad ground, correct? You mentioned it should be at 0 or close to it, but that wires do have some resistance in them. So through several feet of wiring, is that resistance okay?
No, I wouldn't necessarily say 0.4 ohms is okay. See point 2 in
Post #83. Unless that entire path is 40' of wire, that's too much resistance, and with the small amount of current from the meter, compared to the higher current when the relay coil energizes, that may be enough to indicate a problem. A test light on that circuit might provide more information. If it won't light, or is dim, it would show that the ground circuit isn't working.
Correct. I went back and looked at my picture. At the 20k reading it was 0.76. There was a decimal.
Well, that's a head-scratcher. Usually, on 20k, there wouldn't be any decimals, and certainly, it shouldn't be more precise at 20k than 200, which only displays one decimal place. I'll explain a little more about the analog-to-digital (A2D) converter chip, and how it works, but be prepared, you're about to travel down a geeked-out engineering rabbit hole. Buckle up.
Your meter is a "GDT-11." I think the 11 means that it has an 11 bit A2D chip in it due to the scale breakdown on the dial, and based on a tenths decimal place when in 200 ohm mode. Here's how I jumped to that conclusion. The number of bits of an analog-to-digital chip tells you how big the measurement interval is. Each bit is a unit of measure. On the 200 setting, since you have tenths of an ohm capability, that means in absolute value terms, that the minimum value is 0.1 ohms and the max is 200.0 ohms, in 0.1 ohm increments. Bits are powers of 2. Two raised to the 11th power is 2048. If you go from 0.1 to 200.0 by 0.1 increments, there are 2000 possibilities (not counting zero). That's very close to 2048.
What the 11 bit A2D chip does, is whatever dial setting you use, it divides that number by 2049 (because zero counts, so you add 1 to the 2048), and that's your increment of measurement. As you change the dial, the minimum increment changes. This is called the resolution. There may be some other circuitry that does other conditioning and display values in between these increments, but that would just be manipulation of the numbers, not actual measurement. I'm not an electrical engineer, so my understanding is incomplete. So, here is the increment of measurement for each dial setting:
200 ohm is 0.1 ohms (slightly less, actually, but the display won't show hundreths of an ohm)
2000 ohms is 1 ohm
20k ohms is 10 ohms
200k ohms is 98 ohms
2000k ohms is 977 ohms
So, to see "0.76 ohms" on the display for the 20k setting is odd. It should jump from 0 ohms to 10 ohms, and display nothing between them because the 11 bit A2D chip can't discern a difference smaller than 10 ohms on the 20k setting. Weird!
I'd call GB back, but the tech I spoke to said that your meter was discontinued some time ago, and they have very little information on it. I don't think he'd be able to explain it to me.