Instrument Lighting

Fault symptoms
The instrument background lighting is inoperative when the rheostat is activated but the other instrument lighting is OK.

Diagnostic procedure
1 Unplug the main instrument display panel's 3 connectors and connect the Scan Tool's test leads to pin 12 (12p-2) and ground. Then select "TEST" followed by "PULSE".
If in proper working order, the reading obtained should be between 53 and 93 Hz.
The ignition should be switched on.
2 If the reading obtained is not OK, check the wiring for continuity/shorting by measuring the resistance across pin 2 (12p-2) of the main instrument display panel and pin 2 of the rheostat.
The resistance reading obtained should be < 1 ohm.