Centech wiring and power problem

This bronco doesn’t have a heater so when the harness was installed I used the 20 amp heater circuit/wire to power 3 gauges and the switch that turns on the relay for the fuel pump. Has worked fine for several months. All of a sudden it is losing power prior to the fuse box, it also lost power to the turn signal fuse. Every so often just sitting there power on the 20 amp heater circuit will start switching on and off without touching anything, sometimes it will stay on for a few seconds. Also while power is there if you use a turn signal the power on the heater wire switches on and off. There is nothing in the centech directions that helps with troubleshooting where in the harness to look for this. Any ideas appreciated before I rip into the harness. It seems the problem is in the harness prior to the fuse box

Are you accessing the back of the fuse panel at all yet? Check the three (or is it four?) big nuts on the back of the panel to make sure none of them are coming lose.
In all these years, I think I've only seen that happen twice. But obviously it can happen, so check it out.

And for the load you've got on the old heater circuit, I would maybe go down to less than a 10a fuse. Maybe even a 7.5 or something. Reason is that a relay trigger (is it the trigger, or the actual power for the pump?) and a few gauges probably don't draw that much power and could be better protected with a lighter fuse.
Now, if it's powering the fuel pump itself (pin #30 on the relay), then forget I brought up the subject!%)

Hope it's nothing worse than the loose nuts. Otherwise I have no idea where the wires splice together under the harness tape or what might be causing the problem!

Paul

I have seen the nuts corrode on the centech fuse box.

check the solder joints on the fuse box
check the green terminal blocks too for loose screws.

Plan to dig into a little more tonight but the three main leads coming to the back of the fuse panel, I don't have power on the bottom one. All I did was stick a test light back there to check so need to verify it's tight. Checking all the circuits on the fuse side I have power on all except the Heater and the turn signal, which are next to each other. I'm assuming that bottom main wire is for those 2. I hope it's just a matter of cleaning and retightening that connection. Thanks for the replies.

And Paul, correct, the heater wire is only providing power to turn on the relay + the gauges. Changing to a lighter fuse is good idea, thanks.

I spoke with a tech at Centech a few minutes this morning, very very helpful. He says the heater circuit and turn signal comes off the acc post on the back of the ignition switch, so my problem is between the switch and the fuse panel and I should find the problem at one end or the other. If not I'm just going to run a new wire. Also, with that said, I shouldn't be using the heater wire to power the relay for the fuel pump because it doesn't have power when in start, I never noticed. Hopefully I find my current problem and then I'm going to move the fuel pump relay to another post on the back of the fuse panel (with a fuse).
Hope to resolve this tonight.