WARNING - SAFETY - DEFECTIVE "NEW" PRESSURE SWITCH

[quk@isham-research.demon.co.uk (Phil Payne)]

A new brake servo (# 859 612 107) was recently fitted to 85JA900637.

Subsequent testing of revised diagnostic procedures has discovered that
the brake servo pressure switch (# 443 919 081 C) shipped as part of
the assembly is defective, and registers 'open circuit' whether or
not there is pressure in the system.

Obviously this is potentially _extremely_ dangerous, as the warning
light indicating low or no pressure in the brake servo system would
not be illuminated if the servo pressure failed.

This unit is being returned to Audi with appropriate comments.  The
brake servo (and probably also the sensor) was manufactured in late
1991 and is marked "02 92" by Audi - it therefore qualifies as "New
Old Stock".   The original switch has been temporarily refitted.

My (entirely personal) view is that drivers of any Audis equipped with
the tandem pump system (Pentosin/G 002 000) should deliberately
discharge their brake accumulators (by fully depressing the brake
pedal at least 20 times) and check for continuity across the terminals
of the brake servo pressure monitoring switch.

--
 Phil Payne
 Phone: 0385 302803   Fax: 01536 723021
 (The contents of this post will _NOT_ appear in the UK Newsletter.)