To avoid serious or fatal injury 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.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.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.CONDITIONPOSSIBLE CAUSESCORRECTIONA SINGLE LAMP IN THE COURTESY LAMP CIRCUIT DOES NOT ILLUMINATE1. 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 if required.3. Ineffective ground circuit.3. Test and repair the open ground circuit if required.4. Ineffective feed circuit.4. Test and repair the open feed circuit if required.ALL LAMPS IN THE COURTESY LAMP CIRCUIT DO NOT ILLUMINATE1. Ineffective ground circuit.1. Test and repair the open ground circuit if required.2. Ineffective feed circuit.2. Test and repair the open feed circuit if required.3. Courtesy DEFEAT feature turned ON.3. Turn courtesy DEFEAT feature OFF.4. Ineffective courtesy lamp control circuit.4. Test and repair the courtesy lamp control circuit if required.5. Ineffective EMIC inputs or outputs.5. Use a diagnostic scan tool to test the EMIC inputs and outputs. Refer to the appropriate diagnostic information.A SINGLE LAMP IN THE COURTESY LAMP CIRCUIT DOES NOT EXTINGUISH1. Ineffective lamp switch.1. Test and replace a map/reading lamp switch if required.ALL LAMPS IN THE COURTESY LAMP CIRCUIT DO NOT EXTINGUISH1. Ineffective ajar switch.1. Test and replace a door ajar or liftgate ajar switch if required.2. Ineffective ajar switch sense circuit.2. Test and repair the shorted ajar switch sense circuit if required.3. Ineffective TIPM inputs or outputs.3. Use a diagnostic scan tool to test the TIPM inputs and outputs. Refer to the appropriate diagnostic information.4. Ineffective EMIC inputs or outputs.4. Use a diagnostic scan tool to test the EMIC inputs and outputs. Refer to the appropriate diagnostic information.As part of the exterior lighting failsafe feature, upon ignition ON, all of the panel lamps dimmer circuit lamps will illuminate at full intensity and the exterior park lamps and headlamp low beams will illuminate regardless of the left multi-function switch control knob position if the Steering Control Module (SCM) cannot detect an input from the left multi-function switch, or if there is a loss of data bus communication.CONDITIONPOSSIBLE CAUSESCORRECTIONA SINGLE LAMP DOES NOT ILLUMINATE1. Ineffective or missing bulb or Light Emitting Diode (LED) unit.1. Test and replace the lamp bulb or LED unit if required.2. Ineffective ground circuit.2. Test and repair the open lamp ground circuit if required.3. Ineffective feed circuit.3. Test and repair the open lamp feed circuit if required.A SINGLE LAMP DOES NOT EXTINGUISH1. Ineffective feed circuit.1. Test and repair the shorted lamp feed circuit if required.ALL LAMPS DO NOT ILLUMINATE1. Ineffective ground circuit.1. Test and repair the open lamp ground circuit if required.2. Ineffective feed circuit.2. Test and repair the open lamp feed circuit if required.3. Ineffective EMIC inputs or outputs.3. Use a diagnostic scan tool to test the EMIC inputs and outputs. Refer to the appropriate diagnostic information.ALL LAMPS ILLUMINATE AT FULL INTENSITY AT IGNITION ON 1. Ineffective EMIC inputs or outputs.1. Use a diagnostic scan tool to test the EMIC inputs and outputs. Refer to the appropriate diagnostic information.2. Loss of data bus communication.2. Use a diagnostic scan tool to test the data bus. Refer to the appropriate diagnostic information.