Orlando

Interior Backlighting Malfunction

The body control module (BCM) supplies a voltage reference through the 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 through the dimmer switch signal circuit to the BCM. The BCM interprets this voltage signal, then applies a pulse width modulated (PWM) voltage through the backlight lamp control circuit, and the LED dimming control circuit illuminating the LEDs and instrument panel cluster lamps.

Schematic Reference

Interior Lights Dimming Schematics

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. Ignition ON, turn the parking lamps ON, observe the scan tool Indicator LED Backlight Dimming Command parameter while operating the dimmer switch from high to low. The parameter should indicate between 5-48% when the backlight switch is moved up and down.

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

2. Command the LED Backlight Dimming test with the scan tool. The appropriate incandescent lighting items should go ON and OFF.

⇒	If the backlighting does not go ON and OFF, refer to Interior Backlighting Circuit Test.

Dimmer Switch Circuit Test

1. Ignition OFF, disconnect the X1 and X3 harness connectors at the K9 Body Control Module.
2. Ignition ON, test for less than 0.3 V between the signal circuit terminal 9 X1 and ground.

⇒	If greater than the specified value, test the circuits listed below for a short to voltage. If the circuit tests normal, replace the S30 Headlamp Switch.

•	Signal circuit terminal 9 X1

•	12 V reference voltage circuit terminal 4 X3

3. Ignition OFF, test for infinite resistance between the signal circuit terminal 9 X1 and ground.

⇒	If less than infinite resistance, test the circuits listed below for a short to ground. If the circuit tests normal, replace the S30 Headlamp Switch.

•	Signal circuit terminal 9 X1

•	12 V reference voltage circuit terminal 4 X3

4. Test for 7.4-7.9 kΩ between the signal circuit terminal 9 X1 and the 12 V reference voltage circuit terminal 4 X3.

⇒	If less than 7.4 kΩ, test the signal circuit and the 12 V reference circuit for a short circuit. If the circuit tests normal, replace the S30 Headlamp Switch.

⇒	If greater than 7.9 kΩ, test the signal circuit and the 12 V reference circuit for an open/high resistance. If the circuit tests normal, replace the S30 Headlamp Switch.

5. Test for 3.7-4.1 kΩ between the signal circuit terminal 9 X1 and the 12 V reference voltage circuit terminal 4 X3 while turning the thumbwheel for dimming up.

⇒	If not the specified range, replace the S30 Headlamp Switch.

6. Test for 5.1-5.5 kΩ between the signal circuit terminal 9 X1 and the 12 V reference voltage circuit terminal 4 X3 while turning the thumbwheel for dimming down.

⇒	If not the specified range, replace the S30 Headlamp Switch.

7. If all circuits test normal, replace the K9 Body Control Module.

Interior Backlighting Circuit Test

1. Ignition OFF, disconnect the harness connector at the appropriate inoperative backlighting component.
2. Disconnect the negative terminal of the C1 Battery.
3. Test for less than 5 Ω between the ground circuit terminal black wire and ground.

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

4. Reconnect the negative terminal to the C1 Battery.
5. Connect a test lamp between the control circuit terminal yellow wire and ground.
6. Ignition ON, command the LED Backlight Dimming test 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.

7. If all circuits test normal, test or replace the appropriate component with the inoperative backlighting.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.