So I just bought an 85 f150 with thethe 300 I6. I just found out the left rear blinker, brake, and both left and right reverse lights don't work but all the night time lights work. I tried everything from replacing all fuses(including the flasher), changing all bulbs.It still doesn't work. I looked at the wiring and it doesn't look bad. I mean it looks old but not bad. So far no frays or anything like that. The only thing I can think of is a big connector under the hood where all lights, signals, etc. All those wires lead to one group and feed into the cab by the steering column. Any ideas anyone?
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Your reverse lights are more than likely related to the switch.

The brake/turn lamp may be a bad socket. I had to replace both of mine in my 78. They went out within 2 weeks of each other.

Take a voltage meter or a test light and see if the terminal in the socket is getting power, if it isn't move to the wire. My guess is the socket is bad.

 

I checked the socket it looks fine. I don't have multimeter so I can't really test it but the ruinning lights work so is it possible for just two wires being bad or is it probably something else

 

The Brake and turn signal are supplied by the same wire and use the same filament in the bulb.
There are 3 wires in the socket, 1 ground, 1 for the running/tail light and 1 for the brake/turn signal. The bulb is grounded on the side on the metal base and the contacts at the bottom are the positive supply for the 2 bulb filaments.
It is nearly impossible to diagnose the socket by looking at it. Both of mine looked fine but were not.

 

Alright. Thanks again.

 

Look for borked trailer wiring.

 

actually the previous owner did hookup a trailer brake before he sold it to me. Where do you think it would have gone wrong

 

Look for the trailer connector and splices.... probably near the rear license plate.