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 |
|---|---|---|---|---|
TBC 2 Fuse B+ | 2 | 2 | -- | -- |
TBC 5 Fuse B+ | 2 | 2 | -- | -- |
I/P Dimming Voltage Reference | 1 | 1 | 1 | -- |
I/P Dimmer Switch Control | 1 | 1 | 1 | -- |
I/P Lamps Dimmer Switch Signal | 2 | 2 | 2 | -- |
Indicator Dimming Control | B2625 00 | 3 | 3 | -- |
LED Backlight Dimming Signal | B2610 00 | 3 | 3 | -- |
LED Backlight Dimming Control | 3 | 3 | 3 | -- |
Memory Switch Backlight Control | 4 | 4 | 4 | -- |
I/P Dimmer Low Reference | 1 | 1 | 1 | -- |
Memory Switch Backlight Low Reference | -- | 4 | -- | -- |
Headlamp Switch Ground | -- | 1 | -- | -- |
1. Dimmer Switch Malfunction 2. Interior Backlighting Malfunction -- Incandescent 3. Interior Backlighting Malfunction -- LED 4. Memory Switch Indicator Malfunction | ||||
Circuit/System Description
When the ignition switch is turned to the RUN position, the radio's VF displays turn ON at maximum brightness. When the park lamps are ON, all incandescent back lighting turn ON at the dimming level indicated by the instrument panel (I/P) dimmer switch. At the same time all VF displays dim to match the indicated dimming level. The panel dimmer switch potentiometer is an input to the body control module (BCM). When the driver selects a dimming setting by moving the I/P dimming switch potentiometer, all incandescent back lighting lamps are provided with a specific voltage. The incandescent back lighting lamps are then grounded at G201, G302, and G303. When the I/P dimmer switch is moved from MIN to MAX, all vacuum fluorescent (VF) displays, as well as all incandescent back lighting respond from minimum intensity to maximum brightness in response to the I/P dimmer switch.
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 Input 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 Malfunction. |
| ⇒ | If the scan tool dimmer control operates normal, refer to Interior Backlighting Malfunction. |
Circuit/System Testing
Dimmer Switch Circuit Test
- Ignition OFF, disconnect the X1 harness connector from the headlamp switch.
- Test for less than 5.0 ohms between the low reference circuit terminal H and ground.
- Ignition ON, verify that the scan tool Dimming Input parameter displays less than 1.0 volt.
- Install a 3A fused jumper wire between the signal circuit terminal G and the 5.0 volt reference circuit terminal A. Verify the scan tool Dimming Input parameter displays greater than 4.0 volts.
- If the circuits test normal, test or replace the headlamp switch.
| ⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. |
| ⇒ | If the parameter displays greater than the specified value, test the switch signal circuit terminal G for a short to voltage. If the circuit tests normal, replace the BCM. |
| ⇒ | If the parameter displays less than the specified value, test the signal circuit for a short to ground 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 component.
- Ignition OFF, verify that a test lamp illuminates between the listed ground circuit terminal and B+.
- Connect a test lamp between the listed backlighting control circuit terminal and ground.
- Command the dimming test high to low with a scan tool. The test lamp should turn from bright to dim when changing between the commanded states.
- If all circuits test normal, test or replace the inoperative component.
| • | Garage door opener terminal 3 |
| • | Sunroof switch terminal C |
| • | Auxiliary HVAC control module (CJ3) terminal 7 |
| • | Auxiliary HVAC control module (CJ2) terminal A4 |
| • | Transfer case shift control switch terminal D |
| • | IPC terminal A5 |
| • | HVAC control module terminal B9 X1 |
| • | Rear window wiper/washer switch terminal B |
| • | Headlamp switch terminal C X1 |
| • | Upper right SWC switch terminal 5 |
| • | Upper left SWC switch terminal 3 |
| • | Lower left SWC switch terminal 4 |
| • | Lower right SWC switch terminal 4 |
| ⇒ | If the test lamp does not illuminate, test the ground circuit for an open/high resistance. |
| • | Garage door opener terminal 2 |
| • | Sunroof switch terminal B |
| • | Auxiliary HVAC control module (CJ3) terminal 8 |
| • | Auxiliary HVAC control module (CJ2) terminal A5 |
| • | Transfer case shift control switch terminal C |
| • | IPC terminal A7 |
| • | HVAC control module terminal A7 X1 |
| • | Rear window wiper/washer switch terminal C |
| • | Headlamp switch terminal C X2 |
| • | Upper right SWC switch terminal 3 |
| • | Upper left SWC switch terminal 2 |
| • | Lower left SWC switch terminal 1 |
| • | Lower right SWC switch terminal 1 |
| ⇒ | If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM. |
| ⇒ | If the test lamp is always bright, 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, IPC, or HVAC control module replacement, programming, and setup. |
