Hello,

Just enjoying the PreSuper Bowl when I noticed my brake lights were not lighting up?
The rear running lights light up when the lights come on, the turn signals work, the hazards work, the fogs work, The back-up light works.
I checked the fuses all good, I checked the bulbs all good.
I looked at the connections at the rear lights and good on both sides.
I checked under the pedals and the wires are connected to the brake sensor or sending unit. Could the sending unit at the brake pedal maybe have gone bad or is there a relay or something I am missing?


Thanks,

Vysoc

the arm on the light switch may be on the wrong side of the round plate. should be on the rear side. the piston rod free play must be set correctly. p.110 fig 8.4 of your haynes. the correct orientation of the arm is pictured also.

As Kevin pointed out, that switch can be tricky! I spent a lot of time figuring out what was wrong.

For me, it took removing the switch and manually pushing it to convince myself it was not something else. There was a small set screw on mine that I adjusted properly and instant brake lights.

This happened after the replacement of the master cylinder so that likely changed the pedal travel.

Good luck.

Thanks for the ideas, I will get at it later this afternoon, as I was talking about this I had a spare pedal set with an extra switch. I think it is set up in the proper orientation but I will reference the Haynes Manual and get it figured out. Funny you have a forum like this and you forget to check the Haynes book?

Thank you for the suggestions!

Vysoc

Have you worked backwards from the brake light bulb to the switch with a volt meter?

See if you have power at the light bulb
See if you have power at the junction in the engine bay
Power at switch....

Follow the power backwards.

Without looking at the diagram, it should flow power----> fues --->switch ----->lightbulb.

There may be some other feeders going to the blinker switch and the hazard light switch because they use the same bulb.

rich

Thanks for the great leads.

I jumped on this tonight and found nothing wrong with the switch at the pedal, closer investigation showed a dim lighting of the brake bulbs (Testing while the car was running).....would that be a ground problem, my wife was watching at the back said that they got brighter and then dimmer???

Running lights get the same bulbs up to perfect brightness.

I checked the connections again at the rear lights and found nothing amiss.

Like R Towle suggested time to break out the FLUKE Meter.

Any other observations on my Gremlin are welcome.

Thank you,

Vysoc

Bad grounds and possibly corrosion inside the bulb socket.

Brake lights draw more electricity, so bad grounds will show up faster then with tail lights....

Get a multimeter out back test all the connections inside the trunk on the back of the tail light. See if you have power when the brake is applied, use a stick under the seat to hold the brake on while you test.....take two minutes to make one, and less pain than your wife coming out

I had to ream out all my tail lights with a Dremel mounted with a small wire brush....all of the inside (grounds) were corroded enough to have weird issues.

Cleaned all of them, applied dielectric grease to each one, all over the inside.....never had and issue since.

It's a 40 year old socket that has never been cleaned...

instead of that dremel, I make my own sanding "pole".
take a brand new #2 pencil with an unused eraser, a sheet of 400 grit emery paper, a hole puncher, and a glue stick. Glue a dot of sandpaper onto the eraser and use this sanding "pole" to clean the socket contacts, follow up with compessed air to blow out the grindings

Ok,
Took out the running light and brake light bulb, it has two distinct filaments.

Took bulb out looked inside and saw zero signs of corrosion, ran 320 grit over all surfaces that will come in contact. Put on a thin coat of grease (White Lithium).

Started the car up and tested and got the exact same result, all lights work perfect but when I step on the brake I get a weak light up on the brake light left only?

Just tried it again and the running light is up with the lights on but now the weak brake light will not even glow slightly?

Next Step?

Vysoc

Grounds.

Chassis grounds may need to be cleaned.

Look under the relay board in the engine bay, remove it and clean it.
Transmission ground strap...
Fuse panel ground.

Finally, did you check the voltage when you apply the brakes at the light.
Did you follow that back the fuse panel?
Have you removed and cleaned all your fuses...this is a common issue

Look for bad connections of frayed wiring going from the brake lights all the way to the brake switch.

Tomorrow ...Fluke Meter and checking of power all along the way from rear lights forward to the fuse box.

OK thanks r_towle!!!

Vysoc

Are you sure you have the bulbs in correctly? If you look closely, the little pins on the sides of the metal jacket (of the bulb) are in different locations and coincide with the depth of the holders in the socket.

Is it possible the bulbs are installed 180° out?

Basically the bulbs are designed to only go in one way. I think.

Anywho, I got the FLUKE meter out tonight and confirmed the fact that at the rear lights I was receiving the correct voltage for the
+ - Back Up Lights
+ - Wrap around running side markers
+ - Turn Signal lights
+ - Running Lights
The problem is that there is no voltage on either side when the brake is engaged.

So my next step will be to check and see if the brake wire has voltage to the rear brake light.

It's a process, just don't have a lot of time.

Thanks,

Vysoc

OK........... PROBLEM SOLVED

I have been messing with my Fluke Meter and based on no real issues along the line I decided to zone in on the brake light sending unit behind the Pedal Board.
Mine had quite a bit of travel too it.
I found another one I had and messed with it, I thought it was toast because it did not have the range my other one in the car had?

Please reference page 129, figure 9.25 Brake Light Switch adjustment LOCKNUT,
in the Haynes Manual.
I messed with the Fluke meter and received 13 volts while the engine was running, so I knew the switch was working, I made an adjustment to a shorter throw and the next thing I knew my brake lights were fixed.

Oh the sweet feeling of figuring something out with the World's help of course!

So next time someone has tail light brake issues check the adjustment on the Brake Light Adjustment Locknut.

Thanks for a happy ending.

The Bud Light is tasting very good tonight and cannot wait to take the old girl out tomorrow for a spirited romp about the countryside!!!

Happy in Bonita Springs, Florida!!

Vysoc