In my 8970 I have developed an intermittent electrical problem. At first when it was working it would only beep once and all the intelli track lights and the warning / engine stop lights were flashing as if you were initially turning the key on. Then, over the course of a day or so, it progressed to the point where sometimes it would do the above and other times it would spontaneously slip out of gear (change power) or the tractor would die. When he died, the whole board and all the accessories on the board stopped working. The tractor would restart immediately and run for a few minutes and then repeat. If the key was left on, everything remained dark and without light for a few minutes and then sometimes it would turn on slowly and sometimes abruptly. Notably, sometimes the radio would not turn on for an hour or more. I thought it could be a relay, but I moved the relays around and it didn’t get better, I thought it could be the cabin ground, but I cleaned it up and everything looks good and there is no corrosion. The cables are tight and clean on the batteries. I thought it might be the wire to the fuse panel, but it was all tight and not corroded. I don’t think it’s the ignition itself because the terminal block that has keyed power never seems to suffer from any of these issues, even when everything else is kicking in.
If everything else is ruled out, the circuit board is probably the problem. I have several row crops from the 55s / 60s that I have had to “repair” the plate to regain functionality. It could be a loose soldered connection that when it gets hot or bump, it loses the connections. Most of my problems, the relay loses ground. All other relays are still grounded, but one is not. Also female fuse holders loosen and cause problems. The fuse is still good at the top, but it doesn’t make a good connection. My 7760 picker was the worst with the original fuse panel. The plastic on the fuses looks burned at times. Sometimes the fuse holder is loose and needs to be tightened again.