Instrument Lighting Inoperative

Conditions For Fault-Tracing:

VDO Instrument Cluster W/Turbo:

- All gauges on instrument panel working.

Sources of Fault:
- Open-circuit in lighting ground.





1) Checking Indicator Lights:
- Ignition on.
- Switch headlights on.
- Turn instrument lighting rheostat to maximum.
- See if dipped rear (fog) light, main beam and flasher indicator lights come on.

If indicator lights come on:
- Open-circuit in lead to lighting ground between instrument panel terminal # A17 and ground point 31/50.
- Check lead to lighting ground for open-circuit. Checking Cables and Terminals

If indicator lights do not come on:
- Check supply voltage from rheostat, see step 2 below.

2) Checking Supply Voltage From Rheostat:





- Ignition off.
- Expose instrument panel. (Remove dash board cover) Service and Repair
- Undo instrument panel connectors.
- Connect test box to cable harness connector and check ground points. Connecting Test (Breakout) Box

Test Box On Dashboard/Cable Harness Dashboard:

- Connect test box between instrument panel and cable harness connectors.





- Ignition on.
- Switch headlights on.
- Turn instrument lighting rheostat to maximum.
- Connect a voltmeter across test box terminals # 10 (# A10) and # 17 (# A17).
- Voltmeter reading should equal battery voltage.

If reading is correct:
- Fault in instrument lighting bulbs in instrument panel.
- Replace bulbs and test. Instrument Panel Bulb

If reading is incorrect:
- Open-circuit in power supply lead from rheostat between instrument panel terminal # A10 and rheostat terminal 4/4.