Volkswagen Workshop Service and Repair Manuals

Special tools, testers, measuring instruments and auxiliary items required

• ◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
• ◆ Test box V.A.G 1598/22
• ◆ Adapter set V.A.G 1594
• ◆ Diode test lamp V.A.G 1527
• ◆ Current flow diagram

Test conditions

• ● Speedometer OK., checking:

=> Repair group 90, Electrical system

Note:

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

Test sequence

• ‒ Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit with the "Address word" 01. When doing this the engine must be running at idling speed.
  (Connecting fault reader and selecting engine electronics control unit .)
• ‒ Press keys 0, 6 and 1 for "Display group number 61" and confirm entry with Q key.

• ‒ Press keys 0 and 8 for the function "Read measured value block" and confirm entry with Q key.

• ‒ Press keys 0, 0 and 5 for "Display group number 5" and confirm entry with Q key.

• ‒ Carry out test drive and when doing this observe display (2nd person necessary).
• ‒ Observe displayed figure in display zone 3:
       Specification: approx. driven speed
• ‒ Press ⇒key.
• ‒ Press keys 0 and 6 for the function "End output" and confirm entry with the Q key.

If no speed is indicated:

• ‒ → Connect test box V.A.G 1598/22 to control unit wiring harness.
• ‒ Connect diode test lamp between socket 3 (positive) and socket 20 (road speed signal).
• ‒ Raise front left side of vehicle.
• ‒ Switch on the ignition and turn the front left wheel by hand.
• ‒ The diode test lamp should flash (very brief flashes).

Note:

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

• ‒ If the diode test lamp does not flash, check the wiring from contact 20 of engine control unit connector to dash panel insert for open/short circuit.

=> Current flow diagrams, Electrical fault finding and Fitting locations binder