Test sequence

WARNING:

Test equipment must always be secured to the rear seat and operated from there by a second person.
If test and measuring equipment is operated from the passenger seat, the person seated there could be injured in the event of an accident involving deployment of the passenger-side airbag.

If a malfunction of the RPM display at tachometer is detected, signal at the tachometer must be checked.

Read measuring value block display group 001:
See MEASURING VALUE BLOCK 001 .
Perform a road test.
Check indication in display field -1-.
- Specification: The current speed must be indicated (compare with speedometer)

Fig 1: Scan Tool Display - Checking Speed Signal

Courtesy of AUDI OF AMERICA, INC.

If the speed is being indicated, but not at instrument cluster:

If the speed is not indicated:

Remove instrument cluster. See INSTRUMENT CLUSTER, REMOVING AND INSTALLING .
Connect VAG 1598A test box to blue 32-pin multi-pin harness connector using VAG 1598/25 adapter.
Raise vehicle -via lift if possible-, until the front left wheel is free.
Connect multimeter between terminal 28 and 9 for continuity test:
Turn left front wheel.
- The multimeter must deliver short whistling signals.

If test is not OK:

Check wire connection between instrument cluster and speed sensor according to wiring diagram.

If no malfunctions are found in wire: