acbanuchi

So, I have run into a very confusing issue with my tail lights on my 91 f150.

Details:

-all running lights work
-all blinkers work
-right brake light works
-left brake light does not flash when flashers are turned on
-left brake light does not work when brake pedal is depressed
-all bulbs are good
-I have inspected the wiring and I don't see any breaks or anything

AND THE CRAZY PART... When I have the brake pedal depressed and I turn on the right blinker the left brake light works, but only when the right blinker is on.

I am stumped. Please help

PerryB

The brake light circuits go through the turn signal switch. Thats most likely your problem.

acbanuchi

Ya, that's what I was thinking after doing some research on the forum. Is the turn signal switch the same as the multi function switch? The unit in the steering column with the hazard switch?

PerryB

Yes

jereman

I know this is an old thread but I have a similar issue.

Running lights all work
Signals all work
Passenger side Brake doesn't work
Passenger side Hazard doesn't work

No possibility of bad bulbs

Weird part: When I press the brake and check the tail light socket with a meter I get GOOD VOLTAGE. Also when I test the hazards voltage is good. (Same wire -- orange with blue stripe, and same filament in the two way bulb.)

I pulled out the wiring harness from where it "Ys" and you hook up trailer lights to both tail light sockets. No obvious visual problems and no obvious problems with the meter.

Feeling stuck. . .

Any luck with the original poster's problem?

jereman

Update (not the original poster)

It was the multifunction switch, aka signal switch. The one that is under the steering wheel. Lights are 100% now.