Almost no lights after engine harness change.

[Rusty Nail]

All tied together to the starter?

And

The brown wire to the firewall/distributor?

What year truck? Oh. An 81... I may be thinking of a later model green wire.

 

[Silverado81]

The starter had three wires on the large terminal: Positive battery, red to firewall junction, and a light colored wire that was chopped off, live, not hooked to anything, and purple solenoid wire to circuit 6 on bulkhead. On the alternator the batt terminal, and pigtail red wires are spliced together. With my test lead hooked to the splice I get continuity at alternator pigtail, batt terminal, 2J, and 2E terminals. Brown went to 25 on the bulkhead as it should. Then there is the pigtail connection tied into the blue wire on the oil pressure switch connector which ends up at 931 on bulkhead. No oil pressure switch though. Pink to distributor(3), green to temp sender(35), tan to oil sender(31), a green wire to the choke heater. I haven't had time to trace where that wire goes yet. Somehow everything worked in this configuration, not the greatest, but it did work. With the new harness, the truck seems to run better, and the alternator seems to be charging better. 14.50 volts to battery. Gauge stays 1/8 inch above 13, like it used too even with the blower on high before it was stolen, rather than right on 13 when I got it back and on the road again. Just need to power 2J, and I'll be set.

 

[Silverado81]

Here is a crude sketch on how the alternator and starter are physically wired up right now, and voltage at each location. I have voltage everywhere except from the red wire on the pigtail connector to the 2J connection at the firewall. Suggestions please on how to liven things up at 2J!! I'd sure appreciate it. Again this is all brand new wiring, including battery cables, so nothing has rubbed through. All I wanted to do was replace my starter, that went off no problem, but in doing this discovered some very shady wiring, didn't want a fire, so new battery cables, new engine harness = no 2J circuit.

 

[gmachinz]

I'd say on that 2J circuit go ahead and run that wire from the alt plug to the junction, then the junction to the bulkhead. This is the best spot for the remote voltage sensing wire...which is what that is. I've seen OEM harnesses ran like what you've got but it can be re-wired as I described.

 

[Silverado81]

I'd say on that 2J circuit go ahead and run that wire from the alt plug to the junction, then the junction to the bulkhead. This is the best spot for the remote voltage sensing wire...which is what that is. I've seen OEM harnesses ran like what you've got but it can be re-wired as I described.

Ok thank you so much! Will do that and report back tomorrow!

 

[Silverado81]

All is well in my 81 Silverado!

Thanks guys for the help, especially Jabin, that did the trick! Before the harness change if I had my lights on, and A/C on high, I'd barely break 13 volts. Now with everything on, it stays at a solid 14.50 volts, and my voltage gauge no longer twitches. Now I'll loom everything back up and secure the harness. Also I'm going to make sure all the fuses in the panel are the correct value, I saw a couple that are too big for the designated circuit.

 

[gmachinz]

Awesome!