The dual brake pressure switches only detect a failure and light the
Brake Warning light on 80-84 models. In the 85 and newer models VW
installed a brake fluid level warning switch instead. The 80-84 brake
switches have an extra wire lead  for a total of 3 wires each so the
warning switch can work. Later models only have the 2 wire switches and
can't detect a failure.

Mark

Evan Mac Donald wrote:

>AHA! This is a classic Volkswagen gotcha! There is no MECHANICAL swich for the brake lights. There are instead TWO hydralic switches on the side of the brake master cylinder. Either of these switches will make the lights work, but if only one of the switches works, but not the other, the Brake Warning switch will also light up. At least in theory! These switches rarely go bad - usually the connectors get knocked off, or just loose...   ...gee, isn't that a rare thing - wiring faults on a Vanagon! ;-)
>1993 Bonneville
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