Checking Instrument Cluster

For Troubleshooting:
^ Use ammeter and/or digital multimeter Fluke 83 (US 7179) for all electrical checks.
^ Use connector test box V.A.G 1598.
^ Test adapter V.A.G 1598/8.

NOTE: Check battery ground strap connections for tight seating before troubleshooting.

Calling up Test Mode of Instrument Cluster
- The electronic components and instruments in the instrument cluster must be installed in accordance with the respective vehicle equipment. A test mode is integrated in the electronics of every instrument cluster with which it is possible to determine whether the installed instrument cluster is equipped with the proper electronic components and instruments to be able to correctly process and display the vehicle-specific input signals. This test mode can also be used for troubleshooting the instrument cluster and should be interrogated for all complaints pertaining to its function.

Calling Up Test Mode:
- Switch on ignition.
- Press trip odometer button.
- Switch ignition off and then on again while holding down trip odometer button.

NOTE:
- The numbers and data for the selected function appear in the speedometer display. Now every time the trip odometer button is pressed, the next function listed in the table below can be called up in sequence.
- Switching off the ignition exits the test mode.

Troubleshooting - Test Mode Functions - Instrument Cluster:

Distance pulse number:
- If the displayed value does not match the distance pulse number in the table, the distance is incorrectly calculated.
- The distance pulse number is a constant, engine-specific set point value with which the distance pulses of the driven distance can be calculated.

Example: Distance pulse number (from the table) x driven distance = 5482 x 0.5 km = 2741 distance pulses.

Checking Voltages, LEDs and Bulbs on Instrument Cluster
- If a lamp for illuminating (L 10) the instrument cluster or illumination for the digital display light (L 75) fails to light up, first check the respective bulb in the instrument cluster and replace if necessary.

NOTE:
- The warning lamps in the instrument cluster are designed as LEDs (exception: Headlight high beam indicator light). Defective LEDs cannot be replaced.
- If a warning lamp is defective, first troubleshooting must be continued by checking the wiring to the instrument cluster.

Checking Wiring to the Instrument Cluster

Test Conditions:
^ Battery voltage OK.
^ Fuses OK.

Preparations for Checking:
- Use digital multimeter Fluke 83 or 1526 A, test lamp and test box 1598 with adapter cable 1598/8 for checking. The socket designations of the test box V.A.G 1598 are identical to the contact designations on the instrument cluster.
- Switch off ignition.
- Remove instrument cluster.
- Pull multiple connector off instrument cluster.
- Connected test box V.A.G 1598 to 28-pin connector of instrument cluster with adapter cable V.A.G 1598/8 (plug must be felt to engage). Do not connect the instrument cluster to the test box-the adapter connection remains free.
- Set measuring range selector switch of hand multi meter to 20 VDC.

Troubleshooting - Checking The Wiring To The Instrument Cluster:

Test Results:
- If the set point/test result in the test steps is achieved, the wiring to the instrument cluster is OK and the instrument cluster must be replaced.
- If the set point/test result is not achieved, check the wiring to the instrument cluster with the valid wiring diagram.
- If the wiring loom is defective, it must not be repaired. Defective instrument cluster wiring looms must be replaced.