I've been trouble shooting an electrical issue that has me stumped. As part of the restoration of our 1965 F-100 military flare side, we replaced all the wiring with high quality new made OEM type replacement harness's.

I have everything working (head lights and turn signals and flashers) but have an issue. When the ignition switch is on, both turn signal indicator lights on the dash gauge cluster and the high beam lamp on the dash flash on and off together . This happens without any other lights or signals on. Just power up the ignition key switch and the dash only flashes. Truck has both standard turn signal circuit and emergency flasher circuit option. I have sourced the correct flasher units (Used number dummy's post about the correct OEM flasher part numbers) and same problem.

The Ford alternator was rebuilt and upgraded with a solid state regulator. That eliminated the separate voltage regulator on the inner fender

I have the wiring diagrams and am tracing circuits but can't find where the system is picking up voltage from the flasher circuit to those three lights at the same time.

Looking for suggestions.

Thanks

Convoy Driver

 

Does power for all those items come through your ignition switch? If so, that would be first place I’d suspect. You have the factory manual? Check the wiring diagram to verify or rule it out.

I change out electrical items as a matter of course, on a new vehicle - a waste of money, you might say, but 50+ year old vehicles need it. Yeah, I am more parts-swapper, than mechanic, but I’ve got the manual and can manage to get most things done myself -if I choose to.

I got my current 66 last year in January. It had spent more than a decade not being used much. We live in a rainy climate. I have replaced the ignition switch, 1-speed wiper switch, wiper motor, horn relay, w.w. pump, alternator,any and every rusty piece of electrical equipment under the hood. I installed a Pertronix module, plugs, wires. I want to change out the dash light voltage regulator. I also have NOS or good used genuine Ford spares for most of these.The last electrical problem to cure is of my own making- I allowed myself to buy the aftermarket fuel sender (read:Chinese) when an NOS was available. Now, I just received the NOS one to replace it, which I should have done a year ago. I do not mind spending money on the truck, it is old, we rely on it, using it every day for our business.

Sometimes the wiring diagrams in the factory manual are incomplete, or not the best. There are alternative ones available, laminated in plastic, I think. Were available for my 59, should also be for Slicks, and I found it on EvilBay.

 

I solved the problem. The wiring diagrams are not as complete as we would like to see. This turned out to be a dash problem, not a turn signal or emergency flasher circuit problem. The metal dash panel and gauge cluster require a negative ground path. Usually a single wire from the gauge cluster metal housing to the angle brace under the dash in front of the gauge panel. There was an existing screw hole in the brace on my truck. When I added the rubber trim around the edge of the gauge panel it insulated the panel from ground. My truck cab was a basket case that someone else disassembled so I didn't know about the simple ground wire missing but required. The turn signal indicator lights and high beam indicator were flashing when the ignition switch was ON because the constant voltage module was working correctly but the system was seeking a poor path to ground.

Hope that helps someone in the future.

Convoy Driver