[T3] Brake light switches

Jim Adney jadney at vwtype3.org
Tue Feb 21 19:42:35 PST 2012


It's been so dry and warm here that I took the square out for errands 
last week, but coming home a passing pedestrian warned me that my 
brake lights weren't coming on. Thus another pair of brake light 
switches have bit the dust.

Refusing to sacrifice them 2 at a time, I replaced just one on 
sunday, and took the bad one in to work today to cut it apart on a 
lathe. What I found surprised me.

I expected to find the inner contacts corroded and burned, but 
instead, all the metal parts inside were pristine with no signs of 
corrosion or weathering of any kind, and no sign of brake fluid in 
that part of the switch.

Instead, what i found was that there is a little plastic plunger that 
transfers the movement from the diaphram to the metal switch 
contacts. That plastic plunger had melted, so that it could no longer 
move the switch parts. Thus, at least in this case, the contacts were 
not the problem.

The switch that failed was a rather run of the mill, possibly 
Brazilian, part that had a full length hex body. The replacements I 
now have are from Meyle and Euromax and the bodys are half hex/ half 
round, like the OE parts. I cut one of the Meyles apart last year, 
but I don't remember the details about that part of the construction. 
We'll see how this one does.

This plunger could easily be made of metal, eliminating this problem. 
I know that the OG switches had metal plungers. I'll see if I still 
have the email for the Meyle rep. If I do, I'll forward this info to 
him.

In the meantime, I also drilled holes in 4 switches so I could inject 
conductive grease in there to see if that will help. It might help 
with corrosion, but it shouldn't have any effect on the melting 
plunger problem.

-- 
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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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