Vehicle Speed Sensor: Testing and Inspection

Speed signal, checking

Test is valid only for vehicles up to m.y. 2000.

NOTE:
- The vehicle speed signal is generated by the Vehicle Speed Sensor (VSS) -G68- (at transmission) and processed in the instrument cluster.
- The processed signal enters at terminal 54 of the ECM and is used for idle stabilization and tip-in shock reduction during shifting.
- Connect VAS5051 tester or VAG1551 Scan Tool and select control module for engine electronics 1 using "address word" 01. Engine must run at idle for this.

Indicated on display


Rapid data transfer HELP
Select function XX


- Press buttons -0- and -8- to select "Read measuring value block" function 08. Press -Q- button to confirm input.

Indicated on display


Read measuring value block
Enter display group number XXX


- Press buttons -0-, -0- and -5- to select "Display group number 5". Press -Q- button to confirm input.

Indicated on display


Read measuring value block 5 ->
1 2 3 4


- Perform a road test.

WARNING: Secure the Scan Tool (ST) on the rear seat and it have operated from there by a second technician. For this, please observe safety precautions.

- Check specified value for vehicle speed.

Display Group 5:

If the vehicle speed is not indicated.

- Connect VAG 1598/31 test box at wiring harness to Engine Control Module (ECM), do not connect ECM . Connecting VAG 1598/31 Test Box

The following wire connections must be checked for short circuit to B+, short circuit to Ground (GND) and for open circuit:

VAG1598/31 test box,
socket Instrument cluster Terminal
54

Wire resistance: max: 1.5 Ohm

- Repair open circuit or short circuit if necessary.

If no malfunctions are found in wiring:
- Determine all "users" of speed signal (e.g. radio, automatic transmission, A/C system, etc.), disconnect those with a connection to instrument cluster one after another and repeat test until cause is detected.
- Read readiness code. If DTC memory was erased, readiness code must be re-generated. Readiness Code, Generating