1987 with gremlins

[OftenWrongNeverUncertain]

I'm putting a 2.9 back into an 87 4x4 XLT and I'm struggling with electrical issues. I don't know what the 3 relays are on the passenger fender but they click on and off at random, sometimes sounding like Morse code.

The blower fan doesn't work though it has come on a few times at random for no explainable reason. I turn it off and it won't come on again until it feels like it.

The horn won't horn, but I hear a click under the hood when I press it.

The radio gets no power to it or the fuse.
The power windows get no power to them or the circuit breaker, but the breaker has continuity.

The windshield wipers experience the same issue as the power windows. That includes the windshield wash.

I feel something that ties all them together is dead, unplugged, corroded, chewed by a mouse, or ungrounded. But I can't figure it out. Perhaps the relays are related to the issue?

Anyone have any knowledge?

 

[franklin2]

The main feed wire for the whole truck (besides the starter) is a smaller wire hooked to the large terminal on the starter relay on the pass side fender. It then runs from there, hits a couple fusible links, and then runs into the cab to the ignition switch and the fuse box.

It does sound like a grounding problem. It never fails, each time a engine swap out is done, the ground wire that goes from one the of the rear bellhousing bolts or the back of the intake to the firewall is left off. The cab is mounted in rubber body mounts. It has no ground unless this wire is hooked to the engine block. I would check this ground strap first.

 

[rusty ol ranger]

On a 2.9 the cab electronics ground goes from the back of the drivers side head to the firewall

 

[Curious Hound]

I would start by checking grounds. The one from engine to firewall, as mentioned, is often missed. There should be a large ground from battery negative to the starter, often attached to a starter mounting bolt. This ground the engine block. There is another ground from battery negative to the radiator core support, usually above the driver side headlight. I believe there should be one from the engine block to the frame. I don't recall the location of that one. There are other smaller grounding points. But those are the major ones.

 

[OftenWrongNeverUncertain]

I bought a parts truck and got the harness I needed. I got it to rotate but that's all the progress I've had. There is a ground from battery to frame and frame to alternator. That's it from the battery, then there is one from firewall to back of the head, and from exhaust to firewall.