This weekend was more troubleshooting the gauge cluster. For the last year it has had that fault where the gauges don't read right, the back lights are dim and then when you use the turn signals it looks like the whole thing has been possessed. The gauges will bounce from one end of the scale to the other with the indicators, and if the headlights are on then they flash as well. I thought I had it sorted a while ago when I was tidying the trailer connection wiring up and discovered the rear tires had been driving mud into the trailer connection. I had figured that when that got wet it would track power between the connections as they were so close together. As is the case with electrical gremlins, when you make a change it comes right and fools you into thinking you have fixed it, wrong. While it worked fine for a while, it was just a coincidence and later it came back. I checked all of the earths as they are the first go to on these trucks and they were all clean. So then I read @someotherguy mention a dry soldered joint on the circuit board so it was time to pull it out for an inspection. Everything looked good so before getting too committed I thought I would check the socket wiring in the dash since I had a wiring diagram. There are 2 contact points for earths, one goes to the dash frame rail next to the ALDL socket and one goes through to the engine bay. Well the engine bay tester 0 ohms and the one to the dash frame showed 36 ohms. Now I didn't think that 36 ohms would be enough to cause any issues, but that one was the actual problem. Luckily, the metal cover on the back of the cluster has a screw going through the earth track on the circuit board meaning all I had to do was make a short jumper lead that went on one of the cover screws and ran it down to the metal dash frame. I started the truck up with out finishing the connection and the gauges were all off but when I touched the jumper to the metal dash frame it instantly came right, even with the turn signal on so a rear win for me. Now to go through all of the boxes to see what gets done next weekend.