Brake light switch failures

AlanPerry · 02-02-2009, 07:36 PM

I have posted a lot about this on the smart USA insider forums, but it seems a less technical crowd hang out over there.

Around a month ago, my '08 passion locked up in Park. I eventually figured out that it was related to the brake light switch interlock issue. The car was towed to the dealer. They ran a diagnostic scan and found an intermittent brake light switch code and replaced the switch.

As I was driving home, sitting in traffic, the car started beeping and the gear indicator on the dash started flashing. It did this for a few seconds and stopped. Over the next day or so, it did this a few times. Also, the car stalled once. I reported this to the dealer. The service guy suggested that I bring the car back in.

I brought the car in and they scanned it and found that the intermittent brake light switch code was thrown again and replaced the brake light switch again.

In the next day or so, the car did the beeping/flashing thing three more times. I spoke with the dealer and they asked if I could bring the car back in and they would keep it for a week. So, I did (and got a cabrio as a loaner). They looked at it and found nothing wrong, not even a brake light switch failure, even though I had seen the brake light turn off and on while I was holding the brake pedal down.

Here are the two symptoms of the problem:

1. While driving the car, stopped at, for example, a traffic signal or to let pedestrians cross the road, foot firmly on the brake pedal, the car would start beeping and the gear indicator on the dash would flash. At the same time, the brake light would go out. With no change in brake pedal pressure, the beeping/flashing would stop and the brake light would come back on.

2. While driving the car, stopped in a manner similar to the above, the car would stall. I believe that the car was trying to drive because it didn't think that the brake pedal was pressed, but because it was pressed, the car stalled.

I have a hard time believing that the current problem is another brake light switch failure. Maybe is a problem with the brake light switch adjustment. Or, maybe there is a problem with the harness/connector between the brake light switch and the ESP module. I looked around the master cyl assy and the ESP module and the harness doesn't look very substantial but it didn't look damaged either.

At the time that the problems started, the car was less than four months old and had about 2500 miles on it.

I have not observed either problem since I got my car back on Friday, but, since they didn't intentionally fix anything, I don't expect that the problems have been corrected.

Anyone else see an issue like this?

alan

**jwight** · 02-02-2009, 07:59 PM

This is the first one posted here if my memory is correct. If not, someone will correct it!

Old smart · 02-03-2009, 04:10 AM

Yes, it was noted once before. In that case I think it was the result of water getting into the switch from running down the wires, the cure being to loop the wires lower than the switch.

Homework:

Brake Light Switch Failure Locks Shifter.

http://evilution.co.uk/index.php?id=165

AlanPerry · 02-03-2009, 12:50 PM

The brake light switch on the US cars look different from the one in the Evilution how2.

Old smart · 02-03-2009, 01:08 PM

Quote:

Originally Posted by AlanPerry

The brake light switch on the US cars look different from the one in the Evilution how2.

Yeah, that's a W450. But the theory may still be valid.

putzie · 02-03-2009, 01:19 PM

was about to ask if the 451 is the same as the 450? as i dont have a 451 i cant answer that?

AlanPerry · 02-03-2009, 03:21 PM

The US 451 brake master cyl assy looks very similar, if not the same. That looks like a RHD car. I don't see the ESP module in the evilution photos, but it is fairly close to the brake assy, on the left side, in my car.

I didn't open the brake assy up. The parts guy at the dealer showed me a new brake light switch. The plunger was white and did not have the bellows on it.

putzie · 02-03-2009, 05:40 PM

Quote:

Originally Posted by AlanPerry

The US 451 brake master cyl assy looks very similar, if not the same. That looks like a RHD car. I don't see the ESP module in the evilution photos, but it is fairly close to the brake assy, on the left side, in my car.

I didn't open the brake assy up. The parts guy at the dealer showed me a new brake light switch. The plunger was white and did not have the bellows on it.

my smart is lhd and is the same just the box is on the other side of the car, is intresting the one they showed you was white as on the 450's they are brown ,saying that i changed a brake light switch on a friends diesel lhd which was a import and the brake light switch which came out was white which i have never seen one that colour before!

SmartTech · 02-04-2009, 09:52 AM

the brake light switch is located under the access panel directly forward of the brake booster. You have to drop the cover and then you can change switch. How ever smart told us at the tech training that every time you drop the cover you have to replace it (the selaer on the edge is a one shot deal).

AlanPerry · 02-04-2009, 10:21 AM

Just to be clear, I have NO interest in changing the brake light switch at this time. My car is under warranty and the dealer can replace it for the next 21k miles. My situation is that I am on my third brake light switch and want to understand what is going on with my car and whether the problem is now fixed.