Vehicle Speed Signal, Checking

Vehicle Speed Sensor (VSS) signal, checking

NOTE:
- The vehicle speed sensor is generated by the Vehicle Speed Sensor (VSS) -G68 at the transmission and processed in the instrument cluster.
- The processed signal is received at terminal 54 by the Engine Control Module (ECM) and is used for idle stabilization and load change damping during gear shift change.

- Connect Vehicle Diagnostic, Testing and Information System VAS5051 or VAG 1551 Scan Tool and select engine electronics control module by entering address word "01", [1][2]Scan Tool Connecting and Initial Checks. When doing this the ignition must be switched on.

Indicated on display

Rapid data transfer HELP
Select function XX

- Press buttons -0- and -8- to select function "Read Measuring Value Block" and confirm entry with -Q- button.

Indicated on display

Read Measuring Value Block
Input display group number XXX

- Press buttons -0-, -0- and -5- to select "display Group number 005" and confirm entry with -Q- button.

Indicated on display

Read Measuring Value Block 5 ->
1 2 3 4

- Perform road test.

WARNING!
- When driving or riding in an airbag equipped vehicle NEVER hold the scan tool or other test equipment in your hands or lap while in motion. Objects between you and the airbag increase the risk of injury in an accident.
- During a test drive in an airbag equipped vehicle, test equipment must always be fastened to and operated from the rear seat by a second technician. Please observe safety precaution.

- Checking specification for vehicle speed

If vehicle speed is not displayed.

- Connect VAG 1598/31 test box to wiring harness for engine control module. DO NOT connect to engine control module itself, Connecting VAG 1598/31 Test Box

The following wiring connection is to be checked for short circuit to B+, short circuit to Ground (GND) and an open circuit.

VAG 1598/31 Instrument cluster,
test box socket terminal
54

Wiring resistance: max. 1.5 Ohm

If no malfunction is identified in the wiring:
- Determine all "Users" of the vehicle speed signal (e.g. Radio, Automatic Transmission, Climate Control etc.) disconnect in sequence their connection to the instrument cluster and repeat test until cause is determined.
- Display readiness code, Readiness Code Reading. Readiness code must be generated if DTC memory was erased, Readiness Code, Generating