Brake lights

shootupbuddie101 · Post by **shootupbuddie101** » Wed Aug 12, 2009 8:16 pm

It seems as if my brake switch has gone bad and as a result I have 0/3 brake lights working. On my message display it says "brake light circuit" and I have had problems in the past with this message appearing and then finding that all three brake lights are functional. The reason this message appears in the first place is that there is a small piece of melted plastic on one of the fixtures and I think that throws everything off. Also if it is the switch, I will need to find out if it is a 2 or 4 pin. Any insight on my problem?

m20power · Post by **m20power** » Wed Aug 12, 2009 8:58 pm

What car? Is there voltage at the light fixture? Basic t/s will go a long way here. Bob

RealM3E30 · Post by **RealM3E30** » Thu Aug 13, 2009 6:42 am

Bob, talked to Andrew last night, it is a 735-i, E-32??? He has no brake lights at all, I suggested checking the switch first, but with that melted part who knows. R

colin · Post by **colin** » Thu Aug 13, 2009 7:26 am

I actually have a very similar problem (93 740iL). All three brake lights work fine. But as soon as I step on the brake pedal the first time after starting the car, I get the "1 Brake Light' message on the check control.

Last time I messed with this, the passenger side brake light socket did in fact have a melted contact. Actually the whole socket was deformed and I had trouble pulling it out to replace it.

I think if you file off one small tab on the reverse-light socket, it's a perfect replacement for the brake light socket. Cheap way to diagnose before you spend money on parts.

shootupbuddie101 · Post by **shootupbuddie101** » Fri Aug 14, 2009 8:24 pm

Ok so I have done some work. I replaced 4 bulbs that were either blown or didn't look so hot and then checked the continuity from socket to socket and everything seemed to be fine. This means it's probably the brake switch right? Bav auto sells a 4 pin switch and a 2 pin switch, I guess I will need to do some investigating to find out which one I need. If I replace this and the rear brake lights still do not work am I going to have to bring it to the dealer

?

Thanks Robert, yes the car is an e32 735.

m20power · Post by **m20power** » Sat Aug 15, 2009 7:59 am

Is there voltage at the light fixture? If not, check for voltage at the switch.

Bob

shootupbuddie101 · Post by **shootupbuddie101** » Sat Aug 15, 2009 8:35 pm

I just pulled out the brake switch forcefully after fighting with it for about an hour and it broke. Luckily before I did this I figured out that this was what was causing the brakes to malfunction. When the switch is in, the lights are supposed to be off and when it is out, they are supposed to be on. I played around with the mechanism in-out-in-out and discovered a very intermittent pattern that proved the switch went bad. Only sometimes would the lights come on and this is when I PULLED the plunger out all the way. I ordered the new (4 pin) switch overnight and should have it by Tuesday. If anyone wants to help install it, dinner will be on me. I will update once fixed..

colin · Post by **colin** » Sat Aug 15, 2009 9:46 pm

shootupbuddie10 wrote: If anyone wants to help install it, dinner will be on me.

What county are you in? I'm in Middlesex but will be in Atlantic County by Tuesday night.

m20power · Post by **m20power** » Sun Aug 16, 2009 7:34 am

Andrew, when you get your new switch (if it's like the one's I've seen/recall) you'll see that it is held in place by a set of prongs. These prongs must collapse to snap into the bracket. The prongs are prevented from collapsing by a sliding collar. So, you must slide the collar back (or front depending in your view) to allow the prongs to collapse to remove or install the switch. If the collar is not moved, the switch must be forced out, breaking the prongs.

So, slide collar so prongs can collapse, snap-in switch, reposition collar, plug-in wires.

With this trick, you'll see that the install is a 5 minute job, quicker than you can microwave a dinner!

HTH,

Bob

shootupbuddie101 · Post by **shootupbuddie101** » Sun Aug 16, 2009 8:39 am

I am located in Warren county.

About the tabs that must be pushed in, I could not take the white pin or the red collar off and so I probably will not be able to do the reverse during the installation. There is a metal brake piece that must be disconnected in order to be pushed out of the way to allow the removal/installation of the pin and collar.

victory1auto · Post by **victory1auto** » Sun Aug 16, 2009 8:50 am

That 4-wire, 2-pole stop-lamp switch is common to many E32, E34 and E36 models, and is problematic on all of them. One pole of the switch is used to light the stop lamps, while the other is used for monitoring purposes.

The most common problem is where you get the "brake lamp circuit" warning but the stop lamps are working just fine. This is when the "monitoring" pole fails but the other is still working.

The second most common problem is when you get the circuit warning and the stop lamps are not working. This is either a blown fuse, ignition switch problem, or more frequently as you discovered, a failed stop-lamp switch.

The "brake light" messages are different and are usually caused by a blown bulb, high circuit resistance, or a bad ground tab on the lamp assembly. Although it is possible, I have not seen a bad stop-lamp switch cause a "brake light" message.

HTH

Vic

RealM3E30 · Post by **RealM3E30** » Sun Aug 16, 2009 7:49 pm

Thanks All, especially Bob/Vic, I was asked by Andrew to help and hope for a good Cheez/burg meal with a nice shrimp salad. R

shootupbuddie101 · Post by **shootupbuddie101** » Tue Aug 18, 2009 7:00 pm

EMERGENCY...Bob and I just replaced the brake switch and the car does not start now. It seems as if everything else involving the electrical system is fine. The car needs to be able to take me to Weehawken and back tomorrow starting at 4am...

Anyone who can stop by or give assistance over the phone would be a great help.

908 763 9540
Andrew

m20power · Post by **m20power** » Wed Aug 19, 2009 2:37 pm

Hmm...I recall another example when Biscuit + Electrical Work = Emergency. That was a brake light issue as well.

Hope you got it sorted out.

Bob

New Jersey BMW CCA

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