Diagnostic Procedure

STEP	INSPECTION		ACTION
1	Turn the light switch to the ON position. Does the instrument cluster illumination dim according to the illumination setting?	Yes	Troubleshooting completed. (The system is normal.)
1		No	Go to the next step.
2	Inspect the ROOM and ILLUMI fuse. Are the fuses normal?	Yes	Go to the next step.
2	Inspect the ROOM and ILLUMI fuse. Are the fuses normal?	No	Replace the fuse. If the fuse is melted, inspect the wiring harness for short to ground. Repair or replace the wiring harness, then replace the fuse.
3	Retrieve DTCs from the instrument cluster and BCM using the M-MDS. (See DTC INSPECTION [INSTRUMENT CLUSTER] .) (See DTC INSPECTION [BCM] .) Can DTCs be verified?	Yes	Go to the applicable DTC inspection. (See DTC TABLE [INSTRUMENT CLUSTER] .) (See DTC TABLE [BCM] .)
3		No	Go to the next step.
4	Monitor the BCM PID TNS_SW using the M-MDS. (See PID/DATA MONITOR INSPECTION [BCM] .) Does the M-MDS monitored value correspond to the light switch position?	Yes	Replace the instrument cluster. (See INSTRUMENT CLUSTER REMOVAL/INSTALLATION .)
4		No	Inspect the following and repair or replace the malfunctioning location. Light switch (See LIGHT SWITCH INSPECTION .) Vehicle wiring harness between light switch and BCM