Volt

Interior Backlighting Malfunction

The instrument panel dimmer switch is used to increase and decrease the brightness of the interior backlighting components. The instrument panel dimmer switch provides a voltage signal to the body control module (BCM) that will increase as the brightness of the lights are increased and decrease as the brightness of the lights are decreased. The BCM provides a low reference, signal, and B+ voltage reference circuits to the instrument panel dimmer switch. When the instrument panel dimmer switch is placed in the desired position, the dimmed voltage setting is applied from the instrument panel dimmer switch through the instrument panel dimmer switch signal circuit to the BCM. The BCM interprets the signal and applies a pulse width modulated (PWM) voltage through the light emitting diode (LED) dimming control circuits illuminating the interior backlighting to the requested level of brightness.

The instrument panel dimmer switch B+ reference circuit is a low current circuit that will not illuminate a test lamp.

Schematic Reference

Connector End View Reference

Component Connector End Views

Description and Operation

Interior Lighting Systems Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

1. Vehicle in Service Mode, sidelights ON, observe the scan tool LED Backlight Dimming Command parameter while operating the dimmer switch from high to low. The reading should change from a high percentage to a low percentage as the switch is activated.

⇒	If the reading does not change, refer to Dimmer Switch Malfunction.

2. Observe the function of the backlighting components while commanding the LED Backlight Dimming ON and OFF with a scan tool. The backlighting components should turn ON and OFF while changing between the commanded states.

⇒	If the backlighting components do not turn ON and OFF, refer to Interior Backlighting Malfunction.

3. Observe the vehicle ON/OFF switch while adjusting the backlighting from low to high with the dimmer switch. The vehicle ON/OFF switch backlighting should change from low to high as the dimmer switch is operated.

⇒	If the vehicle ON/OFF switch backlighting does not change from low to high as the dimmer switch is operated or is always OFF, refer to Vehicle ON/OFF Switch Backlighting Malfunction.

Dimmer Switch Malfunction

1. Vehicle OFF, disconnect the harness connector at the S16 Driver Information Centre Switch.
2. Vehicle in Service Mode, verify that a test lamp illuminates between B+ and the low reference circuit terminal 12.

⇒	If the test lamp does not illuminate, test the low reference circuit for a short to voltage or an open/high resistance.

3. Test for B+ between the B+ reference circuit terminal 11 and ground.

⇒	If less than the specified range, test the B+ reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module.

4. Verify that a test lamp does not illuminate between the B+ reference circuit terminal 11 and ground.

⇒	If the test lamp illuminates, test the B+ reference circuit for a short to voltage. If the circuit tests normal, replace the K9 Body Control Module.

5. Verify the scan tool LED Backlight Dimming Command parameter is greater than 40%.

⇒	If less than the specified range, test the signal circuit terminal 10 for a short to voltage. If the circuit tests normal, replace the K9 Body Control Module.

6. Vehicle OFF, install a 3 A fused jumper wire between the B+ reference circuit terminal 11 and the signal circuit terminal 10.
7. Vehicle in Service Mode, verify the scan tool LED Backlight Dimming Command parameter is less than 40%.

⇒	If greater than the specified range, test the signal circuit terminal 10 for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module.

8. If all circuits test normal, replace the S16 Driver Information Centre Switch.

Interior Backlighting Malfunction

Note: Each component with backlighting may need to be disconnected to isolate a short to voltage or short to ground. Use the schematics to identify the following:

•	Backlighting components the vehicle is equipped with

•	Each components control and ground circuit terminals

•	Component locations on the backlighting control circuit

1. Vehicle OFF, disconnect the harness connector at any component with inoperative backlighting.
2. Vehicle OFF, scan tool disconnected, all doors closed, all accessories OFF, and wait 2 minutes. Test for less than 10 Ω between the appropriate ground circuit terminal listed below and ground:

•	A20 Radio/HVAC Controls - terminal 17

•	S16 Driver Information Centre Switch - terminal 4

•	E37F Dome/Reading Lamps - Front - terminal 6

•	S25 Garage Door Opener - terminal 3

•	S48B Multifunction Switch - Overhead Console amber LED - terminal 6

•	S70R Steering Wheel Controls Switch - Right - terminal 5

•	S70L Steering Wheel Controls Switch - Left - terminal 7

•	S91 Hand Brake Control Switch - terminal 8

•	S48B Multifunction Switch - Overhead Console - terminal 2

•	S52 Outside Wing Mirror Switch - terminal 11

•	S113 Charge Port Door Open Request Switch - terminal 4

•	S117 Refuel Request Switch - terminal 4

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

3. Connect a test lamp between the appropriate control circuit terminal listed below and ground:

•	A20 Radio/HVAC Controls - terminal 18

•	S16 Driver Information Centre Switch - terminal 3

•	E37F Dome/Reading Lamps - Front - terminal 3

•	S25 Garage Door Opener - terminal 2

•	S48B Multifunction Switch - Overhead Console amber LED - terminal 3

•	S70L Steering Wheel Controls Switch - Left - terminal 6

•	S70R Steering Wheel Controls Switch - Right - terminal 4

•	S91 Hand Brake Control Switch - terminal 6

•	S48B Multifunction Switch - Overhead Console - terminal 1

•	S52 Outside Wing Mirror Switch - terminal 1

•	S113 Charge Port Door Open Request Switch - terminal 5

•	S117 Refuel Request Switch - terminal 5

4. Vehicle in Service Mode, command the LED Backlight Dimming ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	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 K9 Body Control Module.

⇒	If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 Body Control Module.

5. If all circuits test normal, replace the component with inoperative backlighting.

Vehicle ON/OFF Switch Backlighting Malfunction

1. Vehicle OFF, disconnect the harness connector at the S83 Vehicle On/Off Switch.
2. Vehicle OFF, scan tool disconnected, all doors closed, all accessories OFF, and wait 2 minutes. Test for less than 5 Ω between the ground circuit terminal 4 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

3. Connect a test lamp between the control circuit terminal 8 and ground.
4. Vehicle in Service Mode, sidelights ON, activate the dimmer switch from low to high. The test lamp intensity should change from low to high as the dimmer switch is activated.

⇒	If the test lamp is always ON full intensity, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 Body Control Module.

⇒	If the test lamp is always OFF, test the control circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the K9 Body Control Module.

5. If all circuits test normal, replace the S83 Vehicle On/Off Switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.