Pinpoint Test P: The Ambient Lighting Does Not Cycle Through Brightness Settings
Interior Lighting
Pinpoint Tests
Pinpoint Test P: The Ambient Lighting Does Not Cycle Through Brightness Settings
Refer to Wiring Diagram Set 89, Interior Lamps for schematic and connector information. Diagrams By Number
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 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 harness
- Ambient lighting switch
- ILCM
PINPOINT TEST P: 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.
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P1 CHECK THE INPUT FROM THE AMBIENT LIGHTING SWITCH
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: ILCM DataLogger .
- While pressing and releasing the ambient lighting switch up and down, monitor the ILCM ambient lighting switch PID (AmbiDim).
- Does the PID agree with the switch positions?
Yes
GO to P6.
No
If the PID indicates is always pressed, GO to P2.
If the PID indicates idle when the switch is pressed, GO to P4.
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P2 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 DataLogger .
- Monitor the ILCM ambient lighting switch PID (AmbiDim).
- Does the PID still indicate the switch is pressed?
Yes
GO to P3.
No
INSTALL a new ambient lighting switch. REFER to Ambient Lighting Switch Service and Repair. TEST the system for normal operation.
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P3 CHECK THE AMBIENT LIGHTING SWITCH INPUT CIRCUITS FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: ILCM C3498 .
- Measure the resistance between the ILCM C3498-9, circuit CLN61 (WH/VT), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to P6.
No
REPAIR circuit CLN61 (WH/VT) for a short to ground. CLEAR the DTCs. REPEAT the self-test.
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P4 BYPASS THE AMBIENT LIGHTING SWITCH
- Ignition OFF.
- Disconnect: Ambient Lighting Switch C3348 .
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: ILCM DataLogger .
- Monitor the ILCM 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 Service and Repair. TEST the system for normal operation.
No
GO to P5.
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P5 CHECK THE AMBIENT LIGHTING SWITCH INPUT CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: ILCM C3498 .
- Measure the resistance between the ILCM 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 P6.
No
REPAIR circuit CLN62 (BN/BU) for an open. TEST the system for normal operation.
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P6 CHECK FOR CORRECT ILCM OPERATION
- Disconnect the ILCM connector.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the ILCM 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. REFER to Interior Lighting Control Module (ILCM) Service and Repair. 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.
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