brake light issue

[smoothandlow84]

So sometimes both brake lights illuminate while driving and other times the drivers side quits working.

In an ongoing effort to find the problem...

1) checked the brake light bulb....functions as it should
2) checked the bulb socket....functions as it should, good contacts and wiring
3) opened up the tail light wiring loom and traced the power feed wire to the brake light and turn signal to the driver side light (yellow).
4) verified that there is 12v power to the yellow wire when brake pedal is pressed.
5) traced yellow wire all the way up to the firewall and verified 12v power ( I was convinced that I had a break in the wire somewhere between the brake switch and the bulb socket).

......so here is the issue or at least I think.....

I replaced the brake light switch and adjusted it to the pedal to activate when the pedal is pressed. The brake light (drivers side) will illuminate but not alll of the time. Sometimes it works when driving...other times is stops working and I only end up with a passenger side brake light. All other functions work such as turn signal, hazzard lights and running lights.

what have I missed here?

I am still convinced that the problem is the brake switch itself.....or ??? I still have turn signals, but brake light comes and goes. I noticed that there is a plunger type mechanism inside the switch housing. Is it possible for these to be bad right out of the box?

There is also a vacuum line attached to the driver side brake switch as well. I am told that this controls the kickdown for the cruise contol.
The second brake switch behind the pedal controls the passenger side tail light and does not have the vacuum line connection related to the cruise control.

Any input is appreciated

 

[HotRodPC]

Being in intermittent problem, I'd be making sure the ground is good to the light assembly itself too. It is possible to have tail lights and not brake lights or turn signals if the ground is not strong.

But, so how is the turn signals doing? Working all the time everytime?

 

[smoothandlow84]

I will double check the ground connections next. The turn signals both work flawlessly. ....thats why i was thinking it was a power and not ground issue. I tinkered with it today after work and rapidly pressed the brake pedal to see if it decided NOT to work again (thinking the the switch behind the pedal was sticking intermittently )..so far its working...at least for now. I also crawled under the truck and wiggled the power lead (yellow wire -turn signal- brake light lead) to see if i had a loose connection where we had to splice in after the long bed to short bed swap. Brake lights still work.

As far as the ground connection...are you referring to the ground immediately below the tail light on the inside of the rear quarter panel? I removed the driver side tail light housing and saw what appears to be a ground lug/bracket. Im wondering it that could be the problem area.

 

[smoothandlow84]

The last time the driver side brake light didnt didn't work I checked for voltage on the yellow brake light feed and Im not always getting voltage.

 

[HotRodPC]

The last time the driver side brake light didnt didn't work I checked for voltage on the yellow brake light feed and Im not always getting voltage.

So that would lead me to believe also that it's the brake light switch. But how about this? Doesn't the brake light switch actually ground itself through it's mounting bracket? Is it possible where the brake light switch mounts, that the metal is rusty or corroded? Maybe you need to take the switch out, clean up the mounting area with some sandpaper then remount the switch and try it again.

Do both the left and right wires run separate through the brake light switch? If so and one side is working, and one is not, that again would tend to lean toward that side of the switch is defective and it's getting ground just fine since the right side is working OK.

Not sure where our resident electrical experts are on this matter, but one of them need to show up. I'm not a walking Squarebody Schematic like some of us are.

 

[smoothandlow84]

I don't believe so...the brake light switch (both of them) are plastic and have a threaded neck which attaches to the metal bracket behind the brake pedal through a barbed sleeve. There are seperate switches , one for each tail light. The only difference between the two is that the drivers side has a vacuum line on it which deactivates the cruise control when the pedal is pressed. Each switch has a pigtail that connects to each brake light as far as I can determine.
When I i stalled the new switch I also made sure to adjust the length in order for the plunger to extend out when the pedal was pressed (it protrudes out identical to the passenger side switch)

What are the odds that a brand new switch intermittently fails?

Maybe the Chinese kids fell asleep on the assembly line?

 

[smoothandlow84]

So as an update. ...


What are the odds that the brake light problem is related to the hazard light switch? I was performing more troubleshooting last night. I double checked the brake light switch...it works. The bulbs...work, turn signals...work.

so.....since the brake light on the drivers side would not illuminate, i switched on the hazards.....then switched off after verifying that both the front lights and both brake lights flash. I then turned off the hazard switch and pressed the brake pedal. Now both brake lights work as they should. I am beginning to wonder if the hazard lght switch or the wiring to the hazard switch is loose somewhere.

I think this may be the issue since damn near everything else has been checked.

Any suggestions or input on this theory?

I know that whenever the hazard lights are on and the brake pedal is pressed, the flashing stops only to return flashing when the brake pedal is released.

I am also wondering that if the hazard circuit is the issue...maybe the hazard relay is sticking? The hazard relay makes a click on...click off sound. I did replace the hazard relay last year because my lights were not flashing when the hazard switch was on.

 

[Georgeb]

This sounds legit the brake light circuit passes through. Oth the hazard and tun signal switches.

 

[bavoda]

I'm messing with mine and researched my butt off before realizing my break switch just had too much play in it. Now I'm just stuck....how do I take the play out of a 94 chevy non adjustable switch? Like it depresses a bit like it should but I need another good 1/8 of an inch for it to actuate. Anybody know of any fixes?

 

[chengny]

I'm messing with mine and researched my butt off before realizing my break switch just had too much play in it. Now I'm just stuck....how do I take the play out of a 94 chevy non adjustable switch? Like it depresses a bit like it should but I need another good 1/8 of an inch for it to actuate. Anybody know of any fixes?

This applies to a 1991 but it might be the same procedure:

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[smoothandlow84]

I found out that the brake light issue that I have been having is due to the turn signal switch NOT returning to the neutral position after completing a turn. I have to manually push it up to the neutral postion after making LEFT turns or the brake light on the drivers side wont always work.

 

[Honky Kong jr]

Did you pull your wheel yet to take a peek at what's broken?

 

[smoothandlow84]

No, I havent. It's been just too damn hot to gather up the energy to tear down my steering column. Hell, I finally got my hood back from paint (4th time it has been completely stripped down and painted/cut & polished by the paint shop). Im sure the owner of the shop is sick of me coming back time and again, but I have my expectations and spent plenty of money to have the job done to my satisfaction. They have been patient and never charged me any extra since it was their in house issues that caused the problems with the paint. I think that they are more embarrassed then anything else that there were problems.

I damn near sweat off 10 lbs putting the hood back on and aligning it.

I will end up getting into the steering column in September before the carshows start up again.