Hi guys,

I hope I am in the correct forum.

I have a 1993 ford f150 with a 4.9L & 248,000 miles. This weekend i made a 7 hour trip to south texas and traveled at night. I made it home and all my lights functioned properly. I let the truck rest for a few hours before heading out and ended up getting pulled over by a cop and surprising enough my brake lights were out and license plates light also. He just advised me to use my hazards. My headlights work and that is it. When headlight switch is pulled out the headlights light up, the tailights, license plate and corner lenses do not light up. When brake light is pressed, they do not light up either. Turning signals do light up from the tailights as well as the hazards. Any ideas?

I am not much of a mechanic but I am trying to avoid to pay $90 at firestone so they can diagnose it.

Any help is greatly appreciated.

Thanks

 

First thing is to check all the fuses.

You are talking about three different wires (circuits) going to the rear, and none of them work. This sounds like it may be a wiring problem in the rear, and all the wires may have gotten corroded or jerked out by some debris.

 

thanks franklin,

ive checked the fuses and inspected underneath and cant find anything out of the ordinary. how does a clueless guy like me take the next step? what else can i check. sorry for the stupid questions. any advice is greatly appreciated.

 

I missed that in your first post. That means the wiring from the steering column back to the tailights is ok for that circuit. Those wires carry the turn as well as the brake signals.

You also said the "taillights, license plate, and corner lights" do not light up. By corner lights do you mean the front lights? If so, what I would do is pull the headlight switch out and check for burnt wiring at the plug.

The taillight/license plate lights are on what I call a "running light" circuit. This circuit has it's own fuse, and from the fuse it goes down a tan wire to the headlight switch. This tan wire is famous for melting. And this has nothing to do with the headlights. Even though they also operate from the headlight switch, they have their own seperate power source feeding the headlight switch.

After the tan wire goes to the headlight switch, when the switch is turned on, the power for the running lights leaves the switch on a brown wire. This brown wire runs all through the truck from front to rear. So if everything is out, the common point for this circuit is the headlight switch, and if you do not have any melted wires, I would get a meter or testlight and check to see if the brown wire has any power at the headlight switch when the switch is pulled out.

Your brake light problem is on a seperate circuit. See if you can get the running lights working, and then we will work on the brake light circuit. It can be a little bit more complicated.

 

hey franklin,

thanks for the great info! i went this afternoon to try to diagnose the situation with my limited knowledge. I removed the instrument panel to try to test the headlight switch. before i did that i pulled back on the switch and to my astonishment all the lights turned on. so i guess it was alittle loose. saves me $90.00 and plus the charge to fix it. thanks again franklin.

 

hey franklin,

well i thought the problem was fixed all lights work. but now the problem is the brakelights, they still do not function. i forgot about the part you explained that is a whole different story. id appreciate greatly your insight. thanks

 

Here is a diagram of your 1993 Stop and Hazard.

 

The diagram above does not show the beginning of the brake light circuit, but it's only a little bit missing.

The brakes start at the fuse box with a fuse. You said you checked all the fuses. From the fuse, a wire goes to the brakelight switch on the pedal. From the pedal switch it is the lightgreen wire(511) that is coming in on the diagram above at the top right of the diagram.

I think you should have a third brakelight correct? Does it work? If it does not work, then your problem is going to be the brakelight switch, or the wiring feeding the brakelight switch.

The third highmount brake light is fed from the lightgreen wire(511) before it gets to the turnsignal switch.

 

Here is the stop switch.

 

alright hopefully just one more question. i switched the stop switch and got some good luck. if i move it certain ways, brake lights light up. if i move it a tiny bit they shut off and no luck. what is the proper way to mount switch? what procedure do i follow to cailbrate the switch? thanks again!

 

If the picture in this link looks like your setup, then there is no adjustment.
http://www.autozone.com/servlet/UiBr...3d800aa5ff.jsp

Ford has been using this type of switch for many years. Basically the switch mounts over the pedal arm, and surrounds the pin. The switch rides up and down with the pedal motion. The actuator rod for the booster fits over the pedal pin, but is purposely a sloppy fit. When you push on the pedal, all of the slop goes to the rear and it hits the brake switch.

The only thing you can do is replace it, or look for some wires that may be making a bad connection.

 

Hey guys my 93 f150 is having issues with the turn signals not working at all and when I brake and have the turn signal activated the brake light stops working on the same side as activated also my reverse lights are not working either

 

Part or all of your problem is a bad ground in the rear. I have had the sockets go bad and ruin the ground to the bulb, and also some connections back there. The ground originally ran all the way up front to the dash area. But if someone has modified the wiring back there, usually for a trailer hook-up, they may have changed the ground to the frame. That can get corroded and rusty. And also grounding the frame is not a guarantee of a good ground, there are ground straps up front that ground the frame to the battery cable.

The engine block has the large ground from the battery, but the engine, transmission, and the rearend are all mounted in rubber mounts. So ground straps are needed. There is also a ground strap from the back of the engine to the firewall to ground the cab. The cab is mounted in rubber mounts also.

 

Thank you a lot I hope it is a fix as easy as that