Possible causes, elimination, notes

Wire/plug connection between control module and speed sensor not OK (open circuit, short to B+ or short to ground) or the speed sensor itself is damaged.

Check the speed sensor wire and plug connection in the wheel area for damage (visual inspection).

• Check the speed sensor signal with the Porsche System Tester 2 via the Actual values menu (see Test point 2  ). If no speed is displayed when the left front wheel is turned, check the wiring from the control module connector to the speed sensor (following test step).
• Pull off control module connector. Measure internal resistance/continuity between PIN 6 and PIN 7 on the connector (see Connector assignment, control module (ABS and ABS/TC)  .

  Nominal value 1600-1800 ohm.

  If the nominal value is not achieved, check wires and plug connection in the wiring from the front left speed sensor.

  If the nominal value (1600-1800 ohm) is not achieved although the wiring / plug connection is OK, replace the speed sensor.

  Fig 1: Identifying Control Module Connector Pins

  Courtesy of PORSCHE OF NORTH AMERICA, INC.
• Check PIN Inspection for***