Good afternoons Guys, new to the forums, hoping to find some help.

I have a 77 F250 4x4 and having some electrical issues.

I have replaced the turn signal switch 3 times and it has gone bad each time. The last one didn't last a month. I am getting no brake lights on the left side. The last switch went bad and didn't have brake lights on the right side.

They all worked fine when installed. I have replaced all wires from the cab back to eliminate grounding issues (wires had been spliced so many times it looked like the previous owner was practicing splicing). Replaced all bulb sockets as well, cleaned and insured all grounds at sockets were good. All new connections have been soldered and covered with waterproof heat shrink.

The first switch i chalked up to just a bad switch. I changed brands and two bad ones there also. As mentioned earlier, all were fine when installed. When a brake light is noticed to be out, I can pull apart the turn signal switch connector plug and check voltage there, nothing with brakes applied.

Of the three I've replaced, all the wires in the column look good (none nicked or cut)

I'm at a loss, what are the odds all these switches are just bad.

Has anyone had/heard of this issue?

Any help would be greatly appreciated.

 

Is there an old style trailer brake system wired into the factory wiring? Causing some sort of issues? Check your steering column ground? I believe there is one at the rag joint under the hood.

 

There was an old trailer brake/lights box on it. I have removed all that and had it all working.
Not sure about a ground on the column.

The turn signal worked on a bench test before installation.

That's what makes it so weird, there is nothing electronic about the switch only mechanical.

 

TWO different genuine Ford T/S switches: A/T or M/T?

Buying "universal fitz-all" T/S switches from auto parts stores: These are usually made in China, so they may only work for a short time.

 

It is automatic transmission.

Two of them I've had are a brand that I used other parts for years with good luck.

Any chance of getting a Ford part?

 

D3TZ-13341-B .. T/S Switch-Use with A/T / Available From Ford.

1973/77 F100/350 & 1975/77 Econoline except 1975/77's with Speed Control.

MSRP: $74.92 / FTE sponsor silverstatefordparts.com online price: $51.69 ~ Gaudin Ford - Las Vegas NV

 

You da man, I'll give that a whirl