A4 Quattro Wagon L4-1.8L Turbo (ATW) (2000)
Vehicle Speed Sensor: Testing and Inspection
Vehicle Speed Signal, Checking
NOTE:
-
The vehicle speed signal is generated by the speedometer Vehicle Speed Sensor (VSS) -G22- (at transmission) and is 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 control module for engine electronics using "address word". Engine must run at idle.
Refer to "See: Computers and Control Systems/Testing and Inspection
WARNING!
To reduce the risk of accident during road tests, always observe safety precautions.
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
Enter 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 Engine Control Module (ECM), do not connect ECM. Refer to "Scan Tool Testing/Wiring and
Component Testing Using VAG1598/31 Test Box", See: Computers and Control Systems/Testing and Inspection
-
Connect VAG1527B voltage tester to sockets 3 (B+) and 54 (VSS) of VAG1598/31 test box.
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Switch ignition on and turn front left wheel by hand.
-
LED must blink (very brief blink signal).
If LED does not blink:
-
Check following wire connection for open circuit and short circuit to Ground (GND) and B+:
Test box VAG1598/31
Instrument cluster
Socket
Terminal
54
-
Repair open circuit or short circuit if necessary.