Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
LR Park Lamp B+ | 1 | 1 | -- | -- |
I/P Dimmer Switch Signal | 2 | 2 | 2 | -- |
I/P Backlight Signal | 2 | 2 | 2 | -- |
LED Backlight Dimming Control | 1 | 1 | 1 | -- |
Accessory Lamp Backlighting Control | B2622 | 1 | B2623 | -- |
Hazard Switch Backlighting Control | B2622 | 1 | B2623 | -- |
HVAC Control Module Backlighting Control | B2622 | 1 | B2623 | -- |
I/P Dimmer Switch Backlighting Control | B2622 | 1 | B2623 | -- |
Radio Backlighting Control | B2622 | 1 | B2623 | -- |
Rear Window Wiper/Washer Switch Backlighting Control | B2622 | 1 | B2623 | -- |
Sunroof Switch Backlighting Control | B2622 | 1 | B2623 | -- |
Accessory Lamp Backlighting Ground | -- | 1 | -- | -- |
Hazard Switch Backlighting Ground | -- | 1 | -- | -- |
HVAC Control Module Backlighting Ground | -- | 1 | -- | -- |
I/P Dimmer Switch Backlighting Ground | -- | 1 | -- | -- |
Radio Backlighting Ground | -- | 1 | -- | -- |
Rear Window Wiper/Washer Switch Backlighting Ground | -- | 1 | -- | -- |
Sunroof Switch Backlighting Ground | -- | 1 | -- | -- |
I/P Dimmer Switch Low Reference | -- | 2 | -- | -- |
1. Interior Backlighting Malfunction 2. Interior Backlighting Switch Malfunction | ||||
Circuit/System Description
When the ignition switch is turned to the RUN position, the radio VF displays turn ON at maximum brightness. When the park lamps or headlamps are switched ON, all dimmable incandescent back lighting illuminate at the dimming level indicated by the I/P dimmer switch and all the other back lighting lamps illuminate at full intensity. At the same time all VF displays dim to match the indicated dimming level. The panel dimmer switch potentiometer is an input to the BCM. When the driver selects a dimming setting by moving the I/P dimming switch potentiometer, all dimmable incandescent back lighting lamps are provided with a specific voltage. When the I/P dimmer switch is moved from MIN to MAX, all VF displays, as well as all dimmable incandescent back lighting respond from minimum intensity to maximum brightness in response to the I/P dimmer switch The grounding for all of the incandescent back lighting lamps is provided by G105 and G106.
Reference Information
Schematic Reference
Interior Lights Dimming Schematics
Connector End View Reference
Description and Operation
Interior Lighting Systems Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Ignition ON, observe the scan tool Dimming Potentiometer Parameter while operating the dimmer switch from high to low. The voltage reading should change from high to low as the switch is rotated.
| ⇒ | If the reading does not change, refer to Dimmer Switch Circuit Test. |
| ⇒ | If the scan tool dimmer control operates normal, refer to Interior Backlighting Circuit Test. |
Circuit/System Testing
Dimmer Switch Circuit Test
- Ignition OFF, disconnect the headlamp switch connector.
- Verify that a test lamp illuminates between the low reference circuit terminal 3 and B+.
- Ignition ON, verify that the scan tool dimming Potentiometer Parameter displays greater than 4 volts.
- Install a 3A fused jumper wire between the signal circuit terminal 14 and the low reference circuit terminal 3. Verify the scan tool dimming Potentiometer Parameter displays less than 1 volt.
- If the circuits test normal, test or replace the headlamp switch.
| ⇒ | If the test lamp does not illuminate, test the low reference circuit for an open/high resistance. |
| ⇒ | If the parameter displays less than the specified value, test the switch signal circuit for a short to ground. If the circuit tests normal, replace the BCM. |
| ⇒ | If the parameter displays greater than the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM. |
Interior Backlighting Circuit Test
- Ignition OFF, disconnect the harness connector at the inoperative interior backlighting lamp.
- Verify that a test lamp illuminates between the listed component ground circuit and B+.
- Ignition OFF, park lamps ON, verify that a test lamp illuminates between the listed control circuit terminal and ground.
- If all circuits test normal, replace the component with the inoperative backlighting.
| • | Accessory switch terminal 13 |
| • | Hazard switch terminal B |
| • | HVAC control module terminal C |
| • | Rear window wiper/washer switch terminal A |
| • | Radio terminal B5 X1 |
| • | Sunroof switch terminal C |
| • | Headlamp switch terminal 3 |
| ⇒ | If the test lamp does not illuminate, test the ground circuit for a short to voltage or an open/high resistance. |
| • | Accessory switch terminal 12 |
| • | Hazard switch terminal A |
| • | HVAC control module terminal D |
| • | Rear window wiper/washer switch terminal D |
| • | Radio terminal B4 X1 |
| • | Sunroof switch terminal B |
| • | Headlamp switch terminal 6 |
| ⇒ | If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit test normal, replace the BCM. |
| ⇒ | If the test lamp illuminates, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for BCM, HVAC module, or radio replacement, setup, and programming |
