Brake lights won't work when headlights are on...

[Psykosoma]

Hi... Found this site on Google and I was hoping I found the right place to get some quick answers. I have a '93 Toyota Tercel. Here's my problem.

When I have my headlights off, the brake lights work fine. So do the back-up lights and turn signals. But when I turn my headlights on, my brake lights will not work. The back-up lights and the turn signals still work, but my tail lights and brake lights don't work. They are the #1157LL light bulbs that have two filaments. I've checked the fuses under the dash and I checked all the bulbs, just in case. All are fine. From what I've read, this could be a short somwhere in the line, but why would the lights work when the headlights are off and not work when they are on? Any help would be greatly appreciated. Thanks.

[Tercel GTS]

I'd check the multi-function switch. (turn signal) The dimmer and turn signal are built together as is the headlight switch. A malfunction here could cause some crazy results. It's not common this part go out in a toyota though.

[karugs]

You might have reversed the grounding. I would check the grounding lines. They're working, so nothing is wrong, technically. Something has just been misplaced.

[Psykosoma]

Well, I haven't touched the wiring... yet. I will check out that multi-function switch, though.

Something I also noticed, but I may be going nuts... When I turn that knob to turn on the parking lights and headlights, the click you hear sounds louder. I think it does, at least. It may just be me listening for any little thing, but I think it does sound louder. Now I don't mean the click you get at the knob. I mean the click you hear under the dashboard. Could this be indicative of a relay problem?

[CraigW]

Are your brake lamps and turn signals the same bulb on that model ?

[Psykosoma]

If you're asking if I'm using the correct bulbs in the sockets, then yes. I am using 1157 bulbs.

[CraigW]

I was asking if the brake bulb and the turn signals are separate bulbs or combined ? If they are combined there would be a combination switch that would be common to both if they are seperate then it would be two different circuits.

[Tercel GTS]

seperate

[CraigW]

In that case, I would look at the grounds (back and front)

[Tercel GTS]

go into a dark area, turn off all the lights, step on brake pedal, dash lights come on dim, or maybe running lights?

[karugs]

Psykosoma, did you replace the bulbs yourself? Did you check to make sure the grounding wires were correctly installed? If memory serves there are other slots where you could install the wires--other side of the bulb (reversed) that could cause this. Like I said they are fine because they are working, just something is reversed and that could possibly be the grounding.

[spe712]

Hey Everyone,

I have the same problem, however they lights have been working fine on my 1995 Avalon for years, then suddenly I have this problem. I haven't changed the ground just the bulbs. So I'm not sure what would cause this. Any help would be greatly appreciated! Thanks!