83 f150 blinker works but no brake light


#1

I got a new truck bed and decided it was time to finally fix my rear lights. Both blinkers work but only one brake light. It has really got me stumped. Also the rear running lights don’t work and never have. When using a multi meter I get continuity between the running light positive and the common negative but only when the rear light harness is plugged in which means the short is somewhere on the way back or under the dash? Any tips would be appreciated about tracking this stuff down.

thanks


#2

Get a wiring diagram.


#3

I’ve looked at it and the brake signal runs to the directional horn and hazard switch but were is that physically located in the steering column?


#4

The signal switch can be accessed by removing the steering wheel. There are several steps to remove the switch which may be the problem with the brake lights but not the running lights. Surely there is a video online somewhere that illustrates the process.

Getting the snap ring reinstalled on the thrust plate can be a real pain.


#5

The brake light circuit usually passes through the blinker circuit. Since the blinkers work I suggest you check the module for a problem. The connection to the the brake circuit may be faulty for that side that isn’t working. You could also try moving the turn signal arm back slightly to see if that makes it work.

When you measure resistance on the running light circuit you should have some resistance to ground if the running lights are good. You are seeing the resistance of the bulb filaments to ground. If you remove all of the bulbs then you should see an open circuit. If there was a short problem there would be a very low resistance to ground and the fuse for the lighting should blow. You need to look for an open connection to the rear lights. I think you would be smart to purchase a factory wiring manual for the truck. Ebay is a good place to find then at a good price.


#6

Are the grounds good?


#7

The ground seems good. I think I need to pull the steering wheel and test the blinker switch as red knox suggested. A replacement switch is $65 which ain’t worth it to me.