Re: <E28> Brakes

[Jim Cash <j.cash@xxxxxxxxxxxx>]

Harvey Chao writes:

> About half way into the trip down to San Diego from San Jose, on short
> notice, the brake lining warning light started to flicker. 
> 
> Well, the front pads still have about 0.25" or so of material and the sensor
> does not appear to be worn to contact yet.  I did the rear pads about 8-10K
> miles ago and they are fine.
> 
> 1) light flickers when ambient temperatures are above 85 degrees or so and
>    if/when I hit bumps/irregularities in the road.
> 2) light does not come on or flicker when I apply brakes
> 
> Taken in connection with the inspection of the pads (I checked both left front and right rear)
> that showed plenty of pad left and no wear on the sensors, I am thinking of a cold solder joint
> somewhere in the instrument cluster.  


Harvey

When you replaced the rear pads I assume you replaced the sensor as
well.

Did you get the correct sensor "with the long wiring tail" or the short
one that does not allow you to get the electrical connector plug into
the
support clamp ?? (the front and rear sensors are different part numbers)

This happened to me - done by the garage even when the brakes were
rebuilt  ( I have them do it when I need new rotors because I can never
budge the bolts that hold the carriers ).  After about 8 months I was
getting the lamp flashing on bumps.

Turned out that the "unsupported" connector was moving up and down on
every bump.
This finally caused the wiring to breakdown just as it enteres the
connector (car side of trhe wiring).
And any open, or ground,  in the circuit brings on the lamp.

This can also happen if the connector support clamp had broken away, or
the connector has somehow come out of the clamp so that it is no longer
supported.


I had to cut the connector open (that is where the wiring was breaking
down - inside the cable) and then splice/solder in a new piece of wire. 
Then I went back to the dealer and got the long tail sensor.

You can easily test it by manually moving the connector (tug and bend
the wiring) while someone watches the lamp.


Cheers

Jim Cash
London, Ontario, Canada
BMW CCA 102929

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