Brake Lights

[Elaine D]

Hi Guys

In January you guys help me solve my problem with the car running badly. It was actually a combination of the leads and dirty fuel.

We noticed that the brake lights only seem to come on when you press the pedal very hard. It you just touch the brake pedal lightly the brake lights don't work. I have been looking at the manual and there is a stop light switch on the master cylinder, before i go and buy two switches can you tell me if this would be my problem.

Thanks and I can't wait to hear from you.
ED

[slodave]

What year is your car? It does sound as though the car has pressure switches and one has gone bad.

[Elaine D]

Sorry not with it can't believe I forgot to tell you what type of car i have!
Its a 1978 Porche 911 SC Targa

[slodave]

You should have two pressure switches. Replace both.

[911pcars]

Originally Posted by slodave

You should have two pressure switches. Replace both.

The pressure switches still won't allow the brake lights to come on at will. They're preset for a threshold pressure before the contacts meet. The options include adjustable pressure switches (expensive) or use a mechanical switch activated by the brake pedal as used in earlier 911s.

Sherwood

[Rev-it 84]

I had the same problem with my brakes. I replaced the pressure swithes on the master cyl. with new ones only to have the same problem. Finally after a long hard look and a beer I noticed that the switches themslves need to be bleed. That solved the problem for me. Take your pressure switch submerse it in clean brake fluid and take a small rod or nail (no sharp point) and stick it in the orfice (hole), actuate the spring inside to evacuate the air inside and that should do the trick. What causes the problem is that the air inside the switch does not compress at the same rate as the hydro-fluid.

[DRACO A5OG]

Hi Elaine D,

Welcome Back!

Well, I have a solution that will no longer need the replacing of the Brake Light Switch (BLS) ever again and it is not a manual switch at the pedal.

I've developed and tested a relay that will work off of the OEM BLS and Connection Harnesses with out any modifcations. I designed it so you can always go back to OEM Setup for Concours or wanting to kill the BLS again.

You do need to replace the bad BLS's to use my relay at time of installation. 15% Discount for Pelicans

If you are interested please PM me.

[scarceller]

Originally Posted by DRACO A5OG

Hi Elaine D,

Welcome Back!

Well, I have a solution that will no longer need the replacing of the Brake Light Switch (BLS) ever again and it is not a manual switch at the pedal.

I've developed and tested a relay that will work off of the OEM BLS and Connection Harnesses with out any modifcations. I designed it so you can always go back to OEM Setup for Concours or wanting to kill the BLS again.

You do need to replace the bad BLS's to use my relay at time of installation. 15% Discount for Pelicans

If you are interested please PM me.

OK, so how does this relay work?

[DRACO A5OG]

Originally Posted by scarceller

OK, so how does this relay work?

Well, our P-car's brake light system produce too much amps to the brake light switches (BLS), resulting in melting of the internal components. Simply changing out to new BLS's will not address the issue of excessive amps and will most likely last no more than 2-3 months before slow brake light respone re-appears or worse BLS failure.

My Brake Light Switch Arc Suppressor will protect the switches from damage. It is simple to install with Color Coded Diagram and Step by Step Instructions. We also have a Warranty but requires new switches to be installed. Our Host sells the BLS's

Our Device will not repair your current slow brake lights, unfortunately they are damaged and need to be replaced.

PM me for more details, I will do my very best to explain.

[Zeke]

I wish you had these when I had my '77. I went thru BLS's like crazy. Seemed like 3-4 months and I'd have to replace one. I checked them with a meter to make sure I was replacing the correct one. I've never understood why there are two.

[DRACO A5OG]

Hey Milt, sorry, we were kind of slow in developing it. But if your '88 BLS's ever responds slowly our device will fix it. Knock on Wood, I hope they will be true for a long time.

The Secondary BLS were placed as a redundent backup. Unfortunately, the engineers were a bit insecure so they over enginneered the design and allowed too much current to those switches melting both switches at the same time.

[911pcars]

Originally Posted by DRACO A5OG

Hey Milt, sorry, we were kind of slow in developing it. But if your '88 BLS's ever responds slowly our device will fix it. Knock on Wood, I hope they will be true for a long time.

The Secondary BLS were placed as a redundent backup. Unfortunately, the engineers were a bit insecure so they over enginneered the design and allowed too much current to those switches melting both switches at the same time.

More likely a case of German bean counting using under-engineered pressure switches. Maybe they had a few hundred thousand to get rid of in their parts inventory. As for engineering, how much current do two stop lamps generate? Can't be that hard to measure, then source the proper BL switches for long life. The electrical current requirements for 1157 brake light circuits are pretty much identical to all vehicles using..... SAE 1157 bulbs (about 2A each).

But I'm glad you have a long term solution.

Sherwood

[DRACO A5OG]

Originally Posted by 911pcars

Can't be that hard to measure, then source the proper BL switches for long life.

Yes, it was quite easy to measure and it actually fluctuated at 2-3 amps, so really not much draw. I tried in vein to source out both a low pressure and higher amp BLS but manufacturers wanted me to go away and quit bothering their engineers or commit to buying 500+ unit plus engineering fee , uh COD to boot

Originally Posted by 911pcars

The electrical current requirements for 1157 brake light circuits are pretty much identical to all vehicles using..... SAE 1157 bulbs (about 2A each).

Yes, indeed about 1-2 amps. Clearly the dedicated 8 amps is way too much for the lower end of the range and us unlucky ones will have slow brake lights over time 20+ years plus the lucky ones will slow down as well. It is inevitable.

Originally Posted by 911pcars

But I'm glad you have a long term solution.

Sherwood

Thanks Sherwood, yes my company warrants the Premium BOSCH BLS Arc Suppressor for Life and Standard one for 2 Years

[911pcars]

Draco,
Just to clarify - I wasn't pointing the finger at you, It was directed at PAG. It shouldn't have been too difficult for them to determine the electrical requirements for a simple brake light circuit and spec the proper brake switches. Nothing directed at your nice solution.

Sherwood

[DRACO A5OG]

Oh No Sherwood, I Know you didn't Brother!

Thank you for your kind post. I wish I designed it for PAG, I would have a GT3 by now

I am just greatfull that I am not alone in my thinking and that you are informed as to similar thoughts on finding a fix for this unacceptable issue with the BLS's.

My buddy has replaced his BLS's and it failed within 2-3 months. Now his works the way PAG intended with a bit of assistance from my device and no slow down on the Brake Lights.

Jim

[Jesse16]

Are you still selling this modification. I'd be interested in knowing whether its right for my 87 Carrera. Maybe add on to my new switches.

[NOLAsc]

I just got off the interstate (in my 82 SC), and the guy who stopped uncomfortably close behind me pulled alongside at the next red light to tell me that my brake lights were out.

Doesn't seem to matter how far I push the brakes, the lights don't come on. (I'll try hitting them hard when I get a break.) Fuse is good. Are there any other things y'all think I should check before looking at the switch(es) on the master cylinder?

I am at work now, and my books and most of my tools are 10 miles away.

[scarceller]

Originally Posted by NOLAsc

I just got off the interstate (in my 82 SC), and the guy who stopped uncomfortably close behind me pulled alongside at the next red light to tell me that my brake lights were out.

Doesn't seem to matter how far I push the brakes, the lights don't come on. (I'll try hitting them hard when I get a break.) Fuse is good. Are there any other things y'all think I should check before looking at the switch(es) on the master cylinder?

I am at work now, and my books and most of my tools are 10 miles away.

Pull the connectors from the switch at the MC and simply short the 2 together, lights should come on. If shorting the 2 connectors activates the lights the trouble is the switches, replace them both.

You can simply short the connectors at just one of the switches, does not matter which one as they are wired in parallel to each other.

Also look back at this thread Brake Light Switch, Again? post #14-21 - also draco offers a pre-built solution as well.
It covers adding a simple relay fix to help prevent the switches from failing early. What I found when I cut open my old switches was that they to have burned contacts and this I conclude is from too much current flowing through them. I simply added a relay that powers the brake lamps and the switches pick the relay. Was a simple mod that can easily be reversed if need be. I did not cut or alter any existing harness to do this.

Good luck.

[NOLAsc]

Thanks,

Before seeing your response, I went down to the parking garage and found that, yes, when I press hard, the lights come on.

Gotta get back to work, but it looks like tonight I'll be at work in my garage at home.

I'll let you know what happens.

[Jesse16]

I found the switches most easily at my local chain auto parts store, they took one day to get them and least cost. Also the electrical connection was exactly same as my existing switches. I only did one switch since they're pretty easy to get to. My car is 87 carrera.
The switch on pelican is for a wide prong spacing, not what was on my car. Plenty of more complicated fixes are available.