Vehicle Speed Signal, Checking

Vehicle Speed Signal, Checking


Special Tools and Equipment







- VAG1526A
- VAG1527B
- VAG1594A
- VAG1598/31
- VAS5051 with VAG505/1
- or
- VAG1551 with VAG155/3B


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.


Test requirement:
- Function and display of speedometer OK. Troubleshooting:

Test sequence
- Connect VAS5051 tester or VAG1551 scan tool and select the control module for engine electronics using "address word" 01. [1][2]Scan Tool Connecting and Initial Checks
Engine must run at idle for this.


WARNING! Observe safety precautions to reduce the risk of accidents during road test


When indicated on display:

Rapid data transfer HELP
Select function XX


- Press buttons -0- and -8- to select "Read Measuring Value Block" and press -Q- button to confirm input.

When indicated on display:


Read Measuring Value Block Q
Input display group number XXX


- Press buttons -0-, -0- and -5- to select "display group number 005" and press -Q- button to confirm input.

Indicated on display:


Read Measuring Value Block 5 ->
1 2 3 4


- Determining via road test whether vehicle speed is displayed in display field 3.
- If vehicle speed is not display, lift vehicle-if possible using a vehicle lift-until front left wheel is free.
- Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. Connecting VAG 1598/31 Test Box
- Connect VAG1527B voltage tester to sockets 3 (B+) and 54 (VSS) of VAG1598/31 test box.
- Switch ignition on and turn front left wheel by hand.
- LED must blink (very brief blink signal).

If LED does not blink:
- Check the following wire connection for open circuit and short circuit to Ground (GND) and B+:

Test box VAG1598/31 Instrument cluster Terminal
54 -


- Repair open circuit or short circuit if necessary.