Brake lights not working...

[MGPD03]

I have a 2000 Chevrolet Cavalier base sedan.

I recently rebuilt the drum brakes and after bleeding the system I noticed that the two outer brake lights weren't working. The third (deck) light worked as did the parking lights and turn signals/flashers.

I looked at the bulbs and replaced them although the parking lights indicated that the "dim" element worked and the turn signals indicated that the "bright" element worked. I've read that this could be caused by the BOOS (brake on/off switch) so I replaced that...no luck.

The sockets are getting a signal (14-16 ohm) from the BOOS although I'm not sure how strong it would need to be to light the bulb.

I'm fresh out of ideas.....

 

[MGPD03]

As an afterthought, someone mentioned something about a switch that interrupts the brake light when the turn signal is activated. Ideas?

 

[mechtech2]

It sounds coincidental that the lights don't work after your brake job. There shouldn't be a connection.
The third brake and the tail light brake lights are on separate circuits, because of the turn signal function.
14-16 OHM signal??? You should get voltage there, and have a good ground.

 

[MGPD03]

I do believe that it IS coincidental because the only wiring at the hub is the wheel speed sensors and the like (right?).

The only assumed possibility was for me to have damaged/dislodged the BOOS when I was bleeding the brakes.

I'll get a better multimeter on the socket and post it up, the only one I had here at work was a POS (I'm not even sure why we have it)...

 

[MGPD03]

Any ideas...anyone?

Also, I took a closer look at the multimeter and the reading was in volts (not OHMS....don't know what I was thinking). I must have been having a "moment."

 

[Tosh]

Bad ground connection?

 

[MGPD03]

Would the brake lights have a seperate ground? I've checked and rechecked everything that I could think of as a possible cause...

Still nothing.

Does anyone know where the flasher control is on this vehicle?

 

[MGPD03]

Since this is a schizophrenic thread....

I've located the flasher module, replaced it, and still no dice...

The "guy behind the parts counter" recommended that I replace the entire turn signal assembly as they are "prone to failure."

Comments...suggestions?

 

[GMGuy]

I'm not familiar with the cavalier. This flasher module your standard old two prong canister? If it is, changing that will have zero effect on your brake lights. That module only works when you have the turn signal on.
It might be the turn signal assembly. All the wiring for the brakes, hazzards, and turn signals run through the turn signal assembly. All it is is a few moving plastic parts with electrical contacts on it. In the neutral posistion, the brake light signal passes straight through to the bulbs, in a direction indicating posistion the contacts move so that the direction of turn is routed through the signal flasher, and the brake light signal Only goes to the other bulb. If theres a piece of broken plastic its entirely possible to be the cuase of your troubles.

You mention in your initial post that you measured 14volts in the lamp socket. Under what conditions? And where did you ground your voltmeter to take these measurements?
What voltage are you measuring at your brake switch? (ground your voltmeter to a handy metal bit under the dash).

Alex.

 

[kelpie]

Agree with multifunction turnsignal switch.

 

[GMGuy]

Boy, you don't get a lot of time to edit a post. =-)

Another question, what is the bulb arrangement in the cavalier?

Alex.

 

[GMGuy]

One more thing, do the hazzard flashers work?

Alex.

 

[MGPD03]

Bulb arrangement? There is one "dual-filament" bulb on either side of the rear... (Is that what you were asking?)

Yes, the hazards flashers work, BUT the rears won't flash unless you apply pressure to the right and forward on the switch...

I wish I was savvy to the electrical workings on vehicles...heck, the only reason I own a multimeter is for the continuity circuit.

In regards to the reading I got on the bulb socket (I hate to admit that I'm a total idiot, but...) I attempted to reproduce the result only to realize that when I took the initial reading the park lights were on...













...I never claimed to be observant.

 

[GMGuy]

You know its always the seemingly insignificant details that tell the tale, you've found your likely suspect part;
Quote:
BUT the rears won't flash unless you apply pressure to the right and forward on the switch...


You know what part you need to replace.

Not ranting at you here, just directing this at the population at large, but this is a good example of why when describing problems (doesn't matter what the device is) to give a lot of detail in them, as something you mention will stand out like a sore thumb, in this case, having to push on the switch to make things work. In other cases, mentioning everything you have tried doing no matter how small. Saves 20 questions.

Alex.

 

[MGPD03]

I've always been a glutton for doing things the hard way...

I did replace the signal assembly earlier and other that the horn going ape while I was wriggling the new assembly back in...it went pretty well.

Good to go. Thanks for all the help guys.