Brake Pad Problem

[powellae at attbi.com]

sherrow at westol.com asked:

> >Orange warning light came on last week indicating brake pad wear.
> >Checked pad thickness and measured pad wires with a multimeter. Pads
> >measured Ok. Made a shorting plug from old pad connectors and installed
> >in place of pad connector. No change lightr is still lit. Great. Is
> >there a common spot that the wiring from the pads frays and breaks? Any
> >BTDT before I chase the wires all over the engine compartment?

And Tom Christiansen <tomchr at ee.washington.edu> answered...

> That's a pesky one. From either sjmautomatic or 20v.org I gathered that the
> test current runs from the auto check system through the left brake pad,
> then the right brake pad to ground somewhere. You can probably find a more
> accurate definition of "somewhere" in the Bentley Manual... :-) If you
> don't care about the test system and basically just want it to stop beeping
> at you, then I suggest grounding the appropriate wire in the harness for
> the left brake pad. But, obviously, the right way of repairing the system
> would include tracing the wires around and fixing either the bad ground,
> the broken wire, or both.

My Husky list-colleague is right.  That's a pain, but the good news is that Tom
has nailed it - at least on my 1990 200, the circuit comes into the left front
brake pad and goes downstream to the right side from there.  I had the
identical problem and temporarily jumpered (cut and connected) the wires at the
pads, but the real fix was to find the broken wire.

The manual gave me just enough info to follow the circuit - and if memory
serves, what I ended up doing was finding the connector in that circuit above
the LF fender well, plugging in a basic meter to check for continuity, then
wiggling the wire inch by inch between the chassis and the LF pad set.  I found
a broken wire in the 6 inches above the pad set, which makes sense because
that's the part of the wiring that is flexed the most.  It was pretty easy to
cut the bad part of the wiring and replace it with 6" of wire in the center,
keeping both ends intact. Hopefully that's where your break also is.

I recommend using good soldering technique for the repair and using heat-shrink
tubing insulation over the solder connections.  Electrical tape won't last in
that location, but heat-shrink tubing will last just about forever. If you
don't have any, you can get it at Radio Shack or any electronic parts store.
It's cheap and easy to heat with a match.

And BTW - Go Cougs!

Al Powell
Fort Collins, CO
1990 200
WSU '73, '79