Vehicle Speed Sensor: Testing and Inspection

NOTE: The vehicle speed signal originates from the vehicle speed sensor (on the transmission) and is routed to the instrument cluster as well as to the Engine Control Module (ECM).
- Speedometer in instrument cluster OK


Checking
- Using VAG 1551 scan tool, select "Read Measuring Value Block" function 08, display group 003,

Indicated on display


Read measuring value block 3 ->
1 2 3 4


- Observe display field 4 while accelerating from standstill.
- Specified values:
- 0 mph (at standstill)
- Actual speed (vehicle driven)
- Press -> button.
- Select "End Output" function 06.
- Press -Q- button to confirm input.

If no vehicle speed is displayed between standstill and moving:
- Switch ignition OFF and connect VAG 1598/19 test box.
- Connect VAG 1527B voltage tester between test box sockets 13C (signal) and 10D (B+).
- Raise front of vehicle until left-front wheel is free to rotate.


NOTE: The right front wheel must NOT rotate.


- Switch ignition ON.
- Voltage tester must light up at halt strength
- Rotate left front wheel by hand.
- Voltage tester must become brighter (flash)

If tester does not light up (become brighter) or flash:
- Check wiring between test box socket 13X and vehicle speed sensor, using wiring diagram.







- Find and eliminate open circuit in wiring between terminal C13 and vehicle speed sensor.

If wiring is OK, replace vehicle speed sensor.
If voltage tester does not light up (become brighter) or flash, replace ECM.