With Manufacturer's Scan Tool

Speed Signal, Testing

Special tools and equipment
- Scan Tool VAG 1551 or vehicle system tester
- VAG 1552 with cable VAG 1551/3
- Test box VAG 1598/31
- Adapter set VAG 1594
- Diode test lamp VAG 1527
- Wiring diagram

Check conditions
- Speedometer must be OK., checking speedometer:
- The battery voltage must be at least 11.5 V.

NOTE: To check the speed signal the vehicle must be driven. To do this a second person is necessary.


WARNING: Secure Scan Tool to rear seat and operate from this position.


Test sequence
- Connect Scan Tool VAG 1551 (VAG 1552) and select engine electronics control unit with the "Address word" 01. When doing this the engine must be running at idling speed. (Connecting Scan Tool and selecting engine electronics control unit. [1][2][3]Connecting VAG 1551 Scan Tool)

Indicated on display:

Rapid data transfer HELP
Select function XX

- Press buttons -0- and -8- for "Read measured value block" and confirm entry with -Q- button.

Indicated on display:

Read measured value block
Enter display group number XXX

- Press buttons -0-, -0- and -6- for "Display group number 6" and confirm entry with -Q- button.
- Perform road test with a 2nd person to observe display.

Observe the valid safety precautions when carrying out a road test.

Read measured value block 6 ->
xxxkm/h 0 0 0 000000 255

- Observe figure in display field 1.
Specification: approx. road speed

If no speed is indicated:
- Press -> button.
- Press buttons -0- and -6- for "End output" and confirm with the -Q- button.
- Switch off ignition.
- Remove wiper arms and plenum cover.







- Connect test box VAG 1598/31 to control unit wiring harness.
- Connect multimeter to measure voltage between test box sockets 4/5+20.
- Switch on ignition.
- Lift vehicle at front left.
- Rotate front wheel and observe the LED in the LED test lamp. LED must flash. (approx. four times per wheel rotation).

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

If LED test lamp does not flash:
- Check wiring from engine control unit connector contact 20 to dash panel insert for open/short circuit.
- Check DTC memory and, if necessary, repair any malfunctions and then erase. [1][2]Reading Diagnostic Trouble Codes
- Read-out the readiness code. If the DTC memory has been erased or the Diesel Direct Fuel Injection Engine Control Module - J248- was disconnected from permanent battery positive (B+), the readiness code must be generated again.
Monitors, Trips, Drive Cycles and Readiness Codes
Monitors, Trips, Drive Cycles and Readiness Codes