Catastrophic brake light switch failure

[tmadden2]

From left to right:

1. The brake light switch I replaced to try to get some better brake light response time. Worked fine. Should have let sleeping dogs lie.

2. The new switch that lasted two weeks. Had to make a very forceful panic stop to avoid an accident when a driver pulled out in front of me in an intersection. It looked like the switch essentially exploded when the force of the brake fluid pushed it apart. Pushing the brake pedal just pushed fluid out around the switch. Emptied the reservoir during the process of trying to figure out why there was no pressure in the brake pedal. It didn’t fall to the floor, but 90% of the pedal travel did nothing. The last 10% actually slowed the car down a little.

3. The $2 stainless metric bolt from Ace Hardware that held the pressure in the system until the replacement switch could arrive.

4. The new switch.

[GeorgeK]

What brand is the bad switch?

[tmadden2]

Originally Posted by GeorgeK

What brand is the bad switch?

No brand indicated. The only markings on the part are CST081. This was NOT purchased from Pelican, but I wanted to let people know that this type of part failure was possible under a hard braking circumstance.

[manbridge 74]

There really is a difference between makers with seemingly a simple part. Even Porsche branded parts are not exempt but do seem to have less failures (I install Porsche parts daily).

[Jonny H]

Happened to mine on first inspection test after rebuild. Test guy stamped on the pedal as part of braking test and switch burst open just like that.

The genuine Porsche switch costs 10 times the aftermarket one but it's not worth risking your life for.

After this happened to me, I started looking at the aftermarket switches in more detail and discovered that some (meant for VWs) are also not the same pin configuration. Although they will fit the connector, the internal wiring is such that the brake warning light will always come on even after a reset. In my case, the reseller didn't even realise they were selling incompatible parts.

I wrote it up on impact bumpers here:

https://www.impactbumpers.com/forum/index.php?/topic/19911-resetting-the-brake-warning-light/&tab=comments#comment-222859

[Jdub]

What I noted in replacing my OEM with VW versions was that the switch simply did not last as long. Because the price of a pair of real Porsche OEM switches is as expensive as it is, I always suggest you look hard at your M/C and, if old, replace it with a new OEM one with the good switches already in place at a cost less than that of all the pieces.

[tmadden2]

Thanks for the detailed write-up Jonny! It’s amazing how much variance there can be in otherwise-identical parts.

[porsche930dude]

I had problems with them on my jeep. After replacing 4 or 5 I got one from the junk yard an oem part from something and its been good. The aftermarket ones are a joke.