DIAGNOSIS AND TESTING

LAMPS/LIGHTING - INTERIOR

WARNING: To avoid personal injury or death, on vehicles equipped with airbags, disable the supplemental restraint system before attempting any steering wheel, steering column, airbag, occupant classification system, seat belt tensioner, impact sensor, or instrument panel component diagnosis or service. Disconnect and isolate the battery negative (ground) cable, then wait two minutes for the system capacitor to discharge before performing further diagnosis or service. This is the only sure way to disable the supplemental restraint system. Failure to take the proper precautions could result in accidental airbag deployment.

NOTE: When diagnosing the interior lighting circuits, remember that high generator output can burn out bulbs rapidly and repeatedly; and, that dim or flickering bulbs can be caused by low generator output or poor battery condition. If one of these symptoms is a problem on the vehicle, be certain to diagnose the battery and charging system, then repair as necessary.

NOTE: A good ground is necessary for proper lighting operation. If a lighting problem is being diagnosed that involves multiple symptoms, systems, or components, the problem can often be traced to a loose, corroded, or open ground.

The lamps and the hard wired circuits between components related to the interior lighting system may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, details of wire harness routing and retention, connector pin-out information and location views for the various wire harness connectors, splices and grounds.

However, conventional diagnostic methods will not prove conclusive in the diagnosis of the interior lighting system or the electronic controls or communication between modules and other devices that provide some features of the interior lighting system. The most reliable, efficient, and accurate means to diagnose the interior lighting system or the electronic controls and communication related to interior lighting system operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.

COURTESY LAMP CIRCUIT

CONDITION	POSSIBLE CAUSES	CORRECTION
A SINGLE LAMP IN THE COURTESY LAMP CIRCUIT DOES NOT ILLUMINATE	1. Ineffective or missing bulb.	1. Test and replace the courtesy lamp bulb if required.
	2. Ineffective lamp switch.	2. Test and replace a map/reading lamp switch, cargo lamp switch, or sunvisor (vanity lamp switch) if required.
	3. Ineffective ground circuit.	3. Test and repair the open courtesy lamp driver circuit if required.
	4. Ineffective ground circuit (independently switched lamps only).	4. Test and repair the open courtesy lamp load shed circuit if required.
	5. Ineffective feed circuit.	5. Test and repair the open feed circuit if required.
ALL LAMPS IN THE COURTESY LAMP CIRCUIT DO NOT ILLUMINATE	1. Ineffective or missing fuse.	1. Test and replace the fuse if required.
	2. Ineffective ground circuit.	2. Test and repair the open ground circuit if required.
	3. Ineffective feed circuit.	3. Test and repair the open feed circuit if required.
	4. Ineffective cargo lamp (courtesy defeat switch).	4. Test and replace the cargo lamp if required.
	5. Ineffective rear courtesy lamp control circuit.	5. Test and repair the shorted courtesy lamp control circuit if required.
	6. Ineffective multi-function switch.	6. Test and replace the multi-function switch if required.
	7. Ineffective Body Control Module (BCM) inputs or outputs.	7. Use a diagnostic scan tool to test the BCM inputs and outputs. Refer to the appropriate diagnostic information.
A SINGLE LAMP IN THE COURTESY LAMP CIRCUIT DOES NOT EXTINGUISH	1. Ineffective lamp switch.	1. Test and replace a map/reading lamp switch, cargo lamp switch, or sunvisor (vanity lamp, switch and wiring) if required.
	2. Ineffective ground circuit.	2. Test and repair the shorted courtesy lamp driver (ground) circuit if required.
ALL LAMPS IN THE COURTESY LAMP CIRCUIT DO NOT EXTINGUISH	1. Ineffective ajar switch.	1. Test and replace a door, tailgate, or liftglass ajar switch if required.
	2. Ineffective ajar switch sense circuit.	2. Test and repair the shorted ajar switch sense circuit if required.
	3. Ineffective ground circuit.	3. Test and repair the shorted courtesy lamp driver (ground) circuit if required.
	4. Ineffective BCM inputs or outputs.	4. Use a diagnostic scan tool to test the BCM inputs and outputs. Refer to the appropriate diagnostic information.

PANEL LAMPS DIMMER CIRCUIT

CONDITION	POSSIBLE CAUSES	CORRECTION
A SINGLE LAMP DOES NOT ILLUMINATE	1. Ineffective or missing bulb.	1. Test and replace lamp bulb if required.
	2. Ineffective ground circuit.	2. Test and repair open lamp ground circuit if required.
	3. Ineffective feed circuit.	3. Test and repair open fused panel lamps dimmer switch signal circuit if required.
A SINGLE LAMP DOES NOT EXTINGUISH	1. Ineffective feed circuit.	1. Test and repair shorted fused panel lamps dimmer switch signal circuit if required.
ALL LAMPS DO NOT ILLUMINATE	1. Ineffective fused park lamp relay output circuit.	1. Test and repair open fused park lamp relay output circuit if required.
	2. Ineffective or missing park lamp relay.	2. Test and replace park lamp relay if required.
	3. Ineffective fused panel lamps dimmer switch signal circuit.	3. Test and repair open fused panel lamps dimmer switch signal circuit if required.
	4. Ineffective BCM inputs or outputs.	4. Use a diagnostic scan tool to test the BCM inputs and outputs. Refer to the appropriate diagnostic information.
	5. Ineffective ElectroMechanical Instrument Cluster (EMIC) inputs or outputs.	5. Use a diagnostic scan tool to test the EMIC inputs and outputs. Refer to the appropriate diagnostic information.
	6. Ineffective multi-function switch.	6. Test and replace the multi-function switch if required.
ALL LAMPS EXCEPT CLUSTER ILLUMINATION DO NOT EXTINGUISH	1. Ineffective feed circuit.	1. Test and repair shorted fused panel lamps dimmer switch signal circuit if required.