2000 Mazda Protege: No brake lights!! Why?

Was stopped by a woman today who told me that my brake lights were not working. There are three of them and NONE are working!

I cant imagine all three bulbs going out at same time so checked for any blown fuses but they looked OK to me.

So.... it has to be a relay or maybe switch in the brake pedal, right?

Do brake light systems use relays or work direct from switch in pedal?

I see many cars cruising around with only the high-mount, or only one side still working. Years ago I worked at a gas station, and a car came in with all *6* bulbs burned out, so I CAN imagine it. Have you actually pulled any of the bulbs to see if it *is* burned out?

Definitely start with the brake switch. Secondly check or just replace the light relay. Finally make sure you have return or ground to those lights.

"MasterBlaster"

Ok on brake switch

But I'm not finding any info on if the brake light actually work THROUGH a relay!

They do not.

Definitely start with the brake switch. Secondly check or just replace the light relay. Finally make sure you have return or ground to those lights. _____________________________________________________

Quite a few years ago while a friend's '86 RX7 was still relatively new, his brake lights went out and asked if I'd look at them. None of the filaments were bad nor were there any ground corrosion or other issues and given that that the car had never been in an accident requiring body work, I was relativelty certain there were neither resultant wiring nor connector problems so I checked the brake light switch at the pedal, and to my amazement it was fine. The issue turned out to be the 'light monitoring annunciator' (for lack of a better term) system at the top, middle of the dash board. The control board for that system (in the lower left kick panel) had developed a crack ironically knocking out the very lights it was designed to monitor and alert the driver to should any bulbs burn out. He hadn't mentioned to me (and I wasn't aware) that the device existed and had recently stopped functioning. I offered to repair the board but at his disgression I simply and easily bypassed the board and he was back on his way.

Amazing!

A good example of so much complexity that the complexity itself introduces failure points in the system!

Thanks for sharing!

Is that true of all vehicles? If yes, how come? A safety feature of some kind?

OK

Question for the group

What abt replacing all the bulbs with LED versions> That possible and what do LED replacements cost? Is it cost prohibitive?

It is not cost prohibitive, but these LED replacements often do not put out the levels of light that an incandescent bulb for that application would do.

Make sure your old bulbs are bad before redesigning your system.

Often bad grounds, bad wiring, turn out to be the culprit. Brake light switches do fail, but not very often.

Do your diagnosis work first.

Why make the thing more complex than it has to be?

--scott

For the most part, the LED replacement lamps are pretty dreadful. They aren't very easily visible from the sides. Most of them are just a single LED array that go in place of the lamp.

It _is_ possible to make good LED brake lights, but it requires a big array of LEDs and it would require them to be specific to your model car.

Plus, tail light bulbs don't go out often. Just change the bulbs if they are bad, and keep spares in the glove compartment.

--scott

Not true for ALL vehicles but most do not use a relay for the brake lights. One less item to fail that way.

In your case the brake switch gets it power from the 15 amp fuse, To a green wire that runs to the brake switch. From there it follows the green/yellow wire out of the switch through the harness and back to the three brake lights.

If this vehicle has cruise control the Green/yellow wire also feeds a signal to the cruise module to tell it brake position.

Check the fuse first. Then look for 12 volts at the switch on the green wire. Step on the pedal and see if the power goes through the switch.

If you have cruise control take the vehicle out and see if the cruise works and that stepping on the brake disengages it. If that part of it works then the switch is probably OK and the problem is farther back.

The wiring diagram shows that all three lights share a common ground wire as well. It is possible that wire has failed. The way to find that out would be to find the BLACK wires from the brake lights and tap into one with a grounded wire.

Ok that's what I was thinking but needed confirming

Thanks guys!

I will take your advise and check fuse and work from there

Thanks gusy will forget abt LED!

No.

In most cases, it is not necessary to use a relay for the brake lights but there are some exceptions;

Trucks: many when equipped with a trailer towing package will have the trailer circuits connected via relays. The gauge of the wiring has gotten so small that the wiring is not sufficient to carry the current for an extra set of lamps.

Network: many cars (and trucks) are now coming with lamp control modules which could be considered to be a relay of sorts. There is typically one main power feed to a lamp control module, the individual function switches send a network command to the lamp control module which handles the physical act of switching the lamp on.