Pinpoint Test O: The Ambient Lighting Does Not Cycle Through Brightness Settings
Interior Lighting
Pinpoint Tests
Pinpoint Test O: 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 voltage signals to the ambient lighting dimmer switch to monitor the dim up and dim down input requests. When the switch is pressed up or down, it routes the corresponding circuit to ground, indicating a request to increase or decrease the ambient lighting 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 dimmer switch up or down input circuit.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Ambient lighting harness
- Ambient lighting dimmer switch
- ILCM
PINPOINT TEST O: 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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O1 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 dimmer switch, monitor the ILCM ambient lighting dimmer switch PID (AmbiDim).
- Does the PID agree with the switch positions?
Yes
GO to O7.
No
If the PID always reads active, GO to O2.
If the PID always reads idle, GO to O4.
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O2 CHECK THE AMBIENT LIGHTING DIMMER SWITCH FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: Ambient Lighting Dimmer Switch C2305 .
- 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 read active?
Yes
GO to O3.
No
INSTALL a new ambient lighting dimmer switch. REFER to Ambient Lighting Switch Service and Repair. TEST the system for normal operation.
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O3 CHECK THE AMBIENT LIGHTING DIMMER SWITCH INPUT CIRCUITS FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: ILCM C3256 .
- Measure the resistance between the ILCM C3256-9, circuit CLN55 (YE/VT), harness side and ground; and between the ILCM C3256-19, circuit CLN56 (BN/VT), harness side and ground.
- Are the resistances greater than 10,000 ohms?
Yes
GO to O7.
No
REPAIR the circuit in question for a short to ground. TEST the system for normal operation.
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O4 BYPASS THE AMBIENT LIGHTING DIMMER SWITCH
- Ignition OFF.
- Disconnect: Ambient Lighting Dimmer Switch C2305 .
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: ILCM DataLogger .
- Monitor the ILCM ambient lighting switch PID (AmbiDim).
- Connect a fused jumper wire between the ambient lighting dimmer switch C3256-3, circuit CLN56 (BN/VT), harness side and ground; and between the ambient lighting dimmer switch C3256-7, circuit CLN55 (YE/VT), harness side and ground.
- Does the PID indicate active?
Yes
REMOVE the jumper wire. GO to O5.
No
REMOVE the jumper wire. GO to O6.
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O5 BYPASS THE AMBIENT LIGHTING DIMMER SWITCH USING THE CONNECTOR GROUND
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: ILCM DataLogger .
- Monitor the ILCM ambient lighting switch PID (AmbiDim).
- Connect a fused jumper wire between the ambient lighting dimmer switch C3256-3, circuit CLN56 (BN/VT), harness side and the ambient lighting dimmer switch C3256-4, circuit GD116 (BK/VT), harness side; and between the ambient lighting dimmer switch C3256-7, circuit CLN55 (YE/VT), harness side and the ambient lighting dimmer switch C3256-4, circuit GD116 (BK/VT), harness side.
- Does the PID indicate active?
Yes
REMOVE the jumper wire. INSTALL a new ambient lighting dimmer switch. REFER to Ambient Lighting Switch Service and Repair. TEST the system for normal operation.
No
REMOVE the jumper wire. REPAIR circuit GD116 (BK/VT) for an open. TEST the system for normal operation.
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O6 CHECK THE AMBIENT LIGHTING DIMMER SWITCH INPUT CIRCUITS FOR AN OPEN
- Ignition OFF.
- Disconnect: ILCM C3256 .
- Measure the resistance between the ambient lighting dimmer switch C2305-7, circuit CLN55 (YE/VT), harness side and the ILCM C3256-9, circuit CLN55 (YE/VT), harness side; and between the ambient lighting switch C2305-3, circuit CLN56 (BN/VT), harness side and the ILCM C3256-19, circuit CLN56 (BN/VT), harness side.
- Are the resistances less than 5 ohms?
Yes
GO to O7.
No
REPAIR the circuit in question for an open. TEST the system for normal operation.
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O7 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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