With Manufacturer's Scan Tool

Vehicle Speed Signal, Checking
The speed signal is required for A/C compressor cut-off when accelerating, for the Cruise Control System and to improve driveablity smoothness (jolt damping).

Special tools
- VAG 1551/1552 Scan Tool using VAG 1551/3 Adapter cable
- VAG 1598/22 Test Box (MY 1999)
- VAG 1598/31 Test Box (from MY 2000)
- VW 1594 Adapter kit
- VAG 1527B Voltage tester
- Wiring diagram

Checking requirements
- Speedometer function and speedometer display OK.


WARNING!
Secure Scan Tool to rear seat and operate from this position using a second technician.


Test sequence
- Connect VAG 1551/1552 Scan Tool. Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks" Testing and Inspection
- Start engine and let idle.
- Press -0- and -1- buttons to select Address word 01: "Engine electronics"

Display will appear as shown (example only)


038906018M 1.9l R4 EDC 00AG 1813 ->
Coding 0001 WSC XXXXX


- Press -> button.

Display will appear as shown


Rapid data transfer HELP
Select function XX


- Press -0- and -8- buttons to select Function 08: "Read measuring value block".
- Press Q button to enter input.

Display will appear as shown


Read measuring value block HELP
Input Display group number XXX


- Press -0-, -0- and -6- buttons to select "Display group 6".
- Press Q button to enter input.

Display will appear as shown (1 to 4 = Display zones)


Read measuring value block 6 ->
1 2 3 4


- Take a test drive using a 2nd technician to observe display.
- Observe value in Display zone 1
- Specification: approx. speedometer display

If no speed indicated







- Connect VAG 1598/22 (or 1598/31) Test Box to ECM wiring harness.
- Connect diode test lamp between sockets:

Up to MY 1999
- 1 (Ground) and 51 (road speed signal).

From MY 2000
- 4 (Ground) and 20 (road speed signal).
- Switch ON ignition and turn front left wheel by hand.
- Voltage tester diode must blink (approx. four times per wheel rotation)


NOTE: If necessary, hold the front right wheel to prevent it from turning.


If LED does not blink
- Check wiring for open/short circuit between following ECM harness connector terminals and instrument cluster:

Up to MY 1999
Terminal 51

From MY 2000
Terminal 20

- Display the Readiness code. Refer to "Monitors, Trips and/or Drive Cycle (Readiness Codes)/Displaying Readiness Code" Testing and Inspection

If DTC memory was erased
- Set the Readiness code. Refer to "Monitors, Trips and/or Drive Cycle (Readiness Codes)/Setting Readiness Code" Testing and Inspection