Vehicle Speed Signal, Checking
Vehicle Speed Sensor (VSS) Signal, Checking
Special tools and equipment
- VAG1526A
- VAG1527B
- VAG1594A
- VAG1598/31
- VAS5051 with VAG5051/1
or
- VAG1551 with VAG1551/3B
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. Connecting VAS 5051/VAG1551 Scan Tool
Engine must run at idle for this.
WARNING: To reduce the risk of accident during road tests, always observe safety precautions.
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.
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 displayed, 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. Wiring and Component Testing Using VAG1598/31 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 Socket - 54 (Instrument cluster)
- Repair open circuit or short circuit if necessary.