Pinpoint Test M: The Ambient Lighting Does Not Cycle Through Brightness Settings

Interior Lighting

Pinpoint Test M: The Ambient Lighting Does Not Cycle Through Brightness Settings

Normal Operation

The Interior Lighting Control Module (ILCM) sends a voltage reference signal to the ambient lighting switch. When the ambient lighting switch (a momentary contact switch) is pressed, the voltage signal is routed to the ground indicating a request for the module to cycle the ambient lighting to the next brightness setting.

- DTC B2B18 (Ambient Light Switch Input Fault)- a continuous and on-demand DTC that sets when the ILCM (Interior Lighting Control Module) detects a short to ground from the ambient lighting switch input circuit.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors

- Ambient lighting switch

- ILCM (Interior Lighting Control Module)

PINPOINT TEST M : THE AMBIENT LIGHTING DOES NOT CYCLE THROUGH BRIGHTNESS SETTINGS

NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.

M1 CHECK THE INPUT FROM THE AMBIENT LIGHTING SWITCH

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: ILCM (Interior Lighting Control Module) DataLogger.

- While pressing and releasing the ambient lighting switch up and down, monitor the ILCM (Interior Lighting Control Module) ambient lighting switch PID (AmbiDim).

Does the PID agree with the switch positions?

Yes
GO to M6.
No
If the PID indicates the switch is always pressed, GO to M2.

If the PID indicates idle when the switch is pressed, GO to M4.

M2 CHECK THE AMBIENT LIGHTING SWITCH FOR A SHORT TO GROUND

- Ignition OFF.

- Disconnect: Ambient Lighting Switch C3348.

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: ILCM (Interior Lighting Control Module) DataLogger.

- Monitor the ILCM (Interior Lighting Control Module) ambient lighting switch PID (AmbiDim).

Does the PID still indicate the switch is pressed?

Yes
GO to M3.
No
INSTALL a new ambient lighting switch. REFER to Ambient Lighting Switch . TEST the system for normal operation.

M3 CHECK THE AMBIENT LIGHTING SWITCH INPUT CIRCUITS FOR A SHORT TO GROUND

- Ignition OFF.

- Disconnect: ILCM (Interior Lighting Control Module) C3498.

- Measure the resistance between the ILCM (Interior Lighting Control Module) C3498-9, circuit CLN61 (WH/VT), harness side and ground.






Is the resistance greater than 10,000 ohms?

Yes
GO to M6.
No
REPAIR circuit CLN61 (WH/VT) for a short to ground. CLEAR the DTCs. REPEAT the self-test.

M4 BYPASS THE AMBIENT LIGHTING SWITCH

- Ignition OFF.

- Disconnect: Ambient Lighting Switch C3348.

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: ILCM (Interior Lighting Control Module) DataLogger.

- Monitor the ILCM (Interior Lighting Control Module) ambient lighting switch PID (AmbiDim).

- Connect and remove a fused jumper wire between the ambient lighting switch C3348-6, circuit CLN61 (WH/VT), harness side and ground.






Does the PID indicate the switch is pressed with the jumper wire connected?

Yes
INSTALL a new ambient lighting switch. REFER to Ambient Lighting Switch . TEST the system for normal operation.
No
GO to M5.

M5 CHECK THE AMBIENT LIGHTING SWITCH INPUT CIRCUIT FOR AN OPEN

- Ignition OFF.

- Disconnect: ILCM (Interior Lighting Control Module) C3498.

- Measure the resistance between the ILCM (Interior Lighting Control Module) C3498-9, circuit CLN61 (WH/VT), harness side and the ambient lighting switch C3348-6, circuit CLN61 (WH/VT), harness side.






Is the resistance less than 5 ohms?

Yes
GO to M6.
No
REPAIR circuit CLN61 (WH/VT) for an open. TEST the system for normal operation.

M6 CHECK FOR CORRECT ILCM (Interior Lighting Control Module) OPERATION

- Disconnect the ILCM (Interior Lighting Control Module) connector.

- Check for:
- corrosion

- damaged pins

- pushed-out pins


- Connect the ILCM (Interior Lighting Control Module) connector and make sure it seats correctly.

- Operate the system and verify the concern is still present.

Is the concern still present?

Yes
INSTALL a new ILCM (Interior Lighting Control Module). REFER to Interior Lighting Control Module (ILCM) . TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.