Left Brake Light Out

Hi all,

I'm back with another stupid issue. My driver side brake light is not working. So a little background: a month ago I was informed that my PASSENGER side brake light was out, so I did what anyone else would do and got out of the truck and smacked the light a few times and it came back on. Well the issue would intermittently appear so I pulled the light assembly out and noticed that all of the bulb sockets were corroded and rusted to hell. The previous owner replaced the stock assemblies with cheapo smoked out ones. Last week I ordered two new assemblies and as soon as the passenger one arrived I hooked it up and the brake light was functioning as it should. Fast forward the the next day when the driver side assembly shows up... I hook it up and before screwing it in I test the lights. Everything works fine except for the brake light. Wonderful. The brake light worked just fine on the old assembly so I plugged the old one back in and now it's not working either. The issue only started when I changed the assembly out. I'm thinking that one of the wires got screwed up in the plug while trying to unplug the old assembly. My question is, which pin on the plug controls the brake light so I can test it with a multimeter? Also, could this be caused by anything else?

Another thing, what the hell is this thing? Is it another trailer harness? While inspecting the wires I noticed this little guy tucked up in the quarter panel:


Any and all help is appreciated. Thanks!

 

you have a short in the wire harness. it also runs the park lights. it probably shorted out and popped the fuse. that wire harness should be followed to where it goes and removed. that is probably the issue. I had 1 on the back left tail ight on my truck and it was grounding out and turning my light on.

 

Do you mean that now neither brake lights come on? Both stop lights and the high-mounted stop light (on top of the cab) are all connected together. Farther towards the battery is a 15-amp fuse. If the high-mounted stop light comes on, the fuse is good (at least on a 1998 model and most likely on a 2001 as well). See the following diagram:



The two plugs in your photo sure look like a janky wiring job to me. There's a possibility your problem lies there. Maybe the previous owner pulled a trailer at one time and those were for his trailer lights. Maybe there is one of those crimp-on jobs that has worked loose? I would crawl underneath the truck and follow those wires back to wherever they came from, checking for +12 volts at each connection when the brake pedal is pressed.

 

Only the driver side brake light is out. Both of the tail lights work when I turn on the headlights, but the driver side brake light won't light up when I press the pedal.

 

I believe that the tail light and the brake light are together in a single bulb. Assuming nobody has butched the wiring between B6 and the LEFT brake light:

1. Swap the left and right bulbs, press the brake pedal, and with the lights turned off, look at the passenger light. If both bulbs light up in the passenger brake light assembly, then both bulbs are good.
   
   
2. Next, while somebody is pressing the brake pedal, measure the voltage on the driver side brake brake light from each wire behind the socket to vehicle ground. You probably have to remove a tiny piece of the wire(s) going to the back of the bulb socket to make contact. Use a razor blade to do this.
   
   
3. If you have 12 volts at one of the terminals but not at the other, there is either an open wire from the left bulb socket to ground, or the terminals inside the left socket are not making contact with the bulb.
   
   
4. With the lights off, if you have 12 volts at two of the terminals, then remove the bulb from the left light. With nobody pressing the brake pedal, use an ohmmeter to measure the continuity from each contact inside the socket to the frame. Two of the contacts should read infinity and the third contact should read zero ohms. If all three contacts read infinity, then the ground wire or the connection between that wire to the frame is open.

Be sure to let us know what you find.

 

Okay, I'm pretty green when it comes to electronics but I think I understand what you're saying. I'm going to hook up the old assembly that works and use that to test the connections so I don't have to cut into the wires on my new one. If the ground is open, wouldn't the tail light also not work because the tail light and brake light share a ground? I still think a wire pulled loose on the connector when I was unhooking it from the old assembly. Thanks for the instructions.

 

The diagram shows three brake lights and all of them share the same ground. The diagram does not show any tail lights, so I imagine they have a separate connection to ground.

 

Well I fixed it. I don't know exactly what I did but it works now. I tested the voltage on the wires going to the socket and one was giving me a reading and the other wasn't so I figured that much out. I screwed around with the wiring for a few minutes and discovered that one of the terminals going into the connector was a little loose so I smothered the pin on the male end with bulb grease before plugging it back in and it worked after that. I don't know if that was my problem or what, but it works now so I suppose that's good. Thanks for all of the suggestions and help!