• | 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. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
B+, BCM X2 terminal 2 | B2652 00 | B2652 00 | -- | -- |
I/P Dimming Voltage Reference | B1395 03, B3600 03 | B1395 03, B3600 03 | -- | -- |
Instrument Panel Lamp Dimming Control | B2652 00 | 2 | 3 | -- |
LED Backlighting Dimming Control | B2610 00 | 4 | 5 | -- |
Instrument Panel Lamp Dimmer Switch Signal | B3600 03 | B3600 03 | 1 | -- |
Ground - Headlamp Switch | -- | 1 | -- | -- |
1. Headlamps and dimmer switch malfunction 2. Incandescent dimming lamps are inoperative 3. Incandescent dimming lamps are always On 4. LED backlighting is inoperative 5. LED backlighting is always ON |
The body control module (BCM) supplies a voltage reference through the instrument panel (I/P) dimming voltage reference circuit to the interior lamp dimmer switch, which is part of the headlamp switch. When the dimmer switch is placed in a desired brightness position, reference voltage is applied through the dimmer switch rheostat and the I/P lamps dimmer switch signal circuit to the BCM. The BCM interprets this voltage signal, then applies a pulse width modulated (PWM) voltage through the instrument panel lamp dimming control circuit and the LED backlighting dimming control circuit illuminating all backlighting lamps.
Interior Lights Dimming Schematics
Interior Lighting Systems Description and Operation
Control Module References for scan tool information
Ignition ON, observe the scan tool Dimming Control Signal parameter while operating the dimmer switch from high to low. The reading should change from a high percent to a low percent as the switch is rotated.
⇒ | If the reading does not change from a high percent to a low percent, refer to the Dimmer Switch Circuit Test. |
⇒ | If the scan tool dimmer control operates normal, refer to the Interior Backlighting Circuit Test. |
⇒ | If the test lamp does not illuminate, test the ground circuit for an open/high resistance. |
⇒ | If less than the specified value, test the voltage reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM. |
⇒ | If greater than the specified range, test the signal circuit terminal 13 for a short to voltage. If the circuit tests normal, replace the BCM. |
⇒ | If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM. |
• | Headlamp Switch terminal 8 |
• | Rear Heater Switch terminal B |
• | Front Auxiliary HVAC Control Panel terminal B |
• | Rear Auxiliary HVAC Control Panel terminal B |
• | Tow/haul Switch terminal C |
• | SIR Disable Switch terminal F |
• | Electronic Traction Control Switch |
• | Driver Door Window Switch terminal F |
• | Driver Power Lock Switch terminal B |
• | Passenger Door Window Switch terminal C |
• | Passenger Power Lock Switch terminal B |
• | Radio terminal 8 X1 |
• | Driver Information Display Switch terminal 5 |
• | Left Steering Wheel Controls terminal 8 |
• | Right Steering Wheel Controls terminal 1 |
⇒ | If the test lamp does not illuminate, test the ground circuit for an open/high resistance. |
• | Headlamp Switch terminal 7 |
• | Tow/haul Switch terminal B |
• | Traction Control Switch terminal D |
• | HVAC Control Module terminal C |
• | Driver Door Window Switch terminal B |
• | Driver Power Lock Switch terminal C |
• | Auxiliary Blower Motor Switch terminal A |
• | Passenger Door Window Switch terminal B |
• | Passenger Power Lock Switch terminal C |
• | Rear Auxiliary HVAC Control Panel terminal A |
• | Front Auxiliary HVAC Control Panel terminal A |
• | Left Steering Wheel Control Switch terminal 6 |
• | Right Steering Wheel Control Switch terminal 2 |
• | Inflatable Restraint I/P Module Disable Switch terminal D |
• | Driver Information Center (DIC) Switch terminal 4 |
• | Radio terminal 7 X1 |
⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM. |
⇒ | 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 |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for BCM, HVAC, IPC, or Radio replacement, setup, and programming |