Rooster92

Right now I just reconnected it. I am ordering a replacement connector.

I reattached the connector by the battery (the relay harness) to the post on the starter relay. The connector that I said was still in bad shape is the one behind the left headlamp. Thank you for all your tips!

As for the solid blinker... thank you for the tip!

The issue is solved and it has nothing to do with that corroded connector. It turns out, the PO had installed a headlight relay harness. The eyelet where it connects to the starter relay had broken and was disconnected. I had noticed this thing in the engine bay, not knowing what it was at all. I was reading about them here and recognized the picture. Once I reconnected it the headlights came on. The relay harness was tucked there next to the battery this whole time. I got lucky again this time, but that connector is still in terrible shape. Part of me wants to let sleeping dogs lie for fear of causing more damage. Either way, I am going to order a replacement. https://www.amazon.com/Newdeli-Waterproof-Electrical-Automotive-Connectors/dp/B0C5MBSDW2/ref=sr_1_18?keywords=Deutsch&qid=1703281506&sr=8-18&th=1

Now that the truck is starting up, I am addressing the headlight and turn signal issues. The headlights won't turn on at all. The turn signals are intermittent. Sometimes they don't work at all. When they do, one side (left) is ony a solid light. The right side will blink. After reading the @cruiser54 tips, I thought I would start with the connector behind the left headlamp. Right away I find a problem. Some of the pins have broken off entirely. I am looking up how to replace this. There is not a lot of slack in the wire. Any advice is welcome. Once this is fixed I am going to check out the headlight switch itself and add a headlight relay harness. Oh yeah, and the ballast resistor was broken.

I am happy to report that she is now running. Once I re-installed the switch, she started right up! Thank you to everyone that helped me on this thread, especially @Ωhm. Those diagrams you sent were huge.

I do not believe there is an issue with the SR. Since the wire is continuous from the IGN switch all the way to the SR, I figured the issue must be on the battery side. There is no power flowing from the IGN switch to the SR. This schematic shows the red wire going from the IGN switch to the SR, and then from there it goes to the battery. As it turns out, that is continous as well. So, we have a continous wire from the battery, to the SR, to the IGN switch. We also have a continuous wire from the IGN switch to the IGN terminal on the SR. All that is left is to connect the two. So I went ahead and jumped it. Once I connected the red to green, the engine turned. As I understand it, that only leaves one possible point of failure: The IGN switch. Like I said earlier, I replaced that aready. So, its either a bad switch out of the box (unlikely) OR I installed it incorrectly (much more likely). Either way, I am going to step away from it until tomorrow.

I got a positive continuity check on both 5 and Ground.

Honestly, I believe that the terminals on the SR are mislabled. That is why my wires appeared to be backwards on the original picture I took. I also saw a video on youtube of a guy working on an XJ... he mentions something similar around the 4:10 mark. https://youtu.be/baU6_wBkk8k

Yes. Also, connected + straight to G. That engaged the starter motor as well.

I removed the wire from the "I" terminal. Then I connected a jumper cable from the bare "I" terminal on the SR to the + terminal on the battery.

When I connected the IGN relay terminal straight to the positive end of the battery, nothing happened. I then took the same jumper cable and connected the solenoid wire straight to the positive end of the battery. The starter motor engaged.

D2 4 does show voltage with the key turned

Where is that located?

You are correct. I have no idea how that could have happened. Also, I have been testing each of those wires to confirm which one goes to the ignition. I have connected them one by one to a multimeter while turning the key. The sad news is... none of them had a jump in voltage when I tried to crank the engine. Not good.