Saab: Brake Warning Light on, brake warning light, saab 900s

Question
QUESTION: Hi, I have a SAAB 900s, 1997.  Just recently my brake warning light comes on very quickly and at the same time my spedometer needle goes to zero.  It happens very fast, basically a flicker and the warning signal sounds.  What can this be?

ANSWER: Lisa:
 As stated in my profile,my hands on experience is limited to the older SAABS. Therefore, I can only guess that is a loose electrical connection to the instrument oanel, and because its intermittent, is very difficult to locate. If you could link any other action to this phenomenon, that would help narrow it dowm. In general, since it apparently goes away immediately,and has no effect on any other part of the car's operation, then there is nothing to be concerned about.

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QUESTION: Hi, thanks for the reply.  Someone thought it might be my ABS Control Unit.  Apparently these do fail as the cars get older.  Thoughts?

Answer
Lisa:
 I am inclined to put the fault at the ABS/speedometer sensor itself, again as some intermittentent connection since that would be a point common to both ABS & speedometer functions. Electronic devices, such as the control unit do not usually fail in the manner you described.
        Jerry