Pinpoint Test B: The Courtesy Lamps Do Not Illuminate From The Instrument Panel Dimmer Switch
Interior Lighting
Pinpoint Test B: The Courtesy Lamps Do Not Illuminate From The Instrument Panel Dimmer Switch
Normal Operation
The Steering Column Control Module (SCCM) sends 3 voltage signals to the instrument panel dimmer switch to monitor the DIM UP, DIM DOWN and DOME LAMP request inputs. The SCCM (Steering Column Control Module) sends a message over the communication network to the Body Control Module (BCM) to indicate the instrument panel dimmer switch position.
The BCM (Body Control Module) turns the courtesy lamps on and off by monitoring the dimmer switch and dome lamp request input circuits. When the instrument panel dimmer switch is pressed to the second detent up, the SCCM (Steering Column Control Module) receives signals indicating DIM UP and DOME LAMP request circuits at the same time, indicating a request to turn the courtesy lamps on. When the instrument panel dimmer switch is pressed to the second detent down, the SCCM (Steering Column Control Module) receives signals indicating DIM DOWN and DOME LAMP request circuits at the same time, indicating a request to turn the courtesy lamps off. When the SCCM (Steering Column Control Module) detects these inputs from the instrument panel dimmer switch, the SCCM (Steering Column Control Module) sends the appropriate message to the BCM (Body Control Module) and voltage is supplied to the courtesy lamps.
If the SCCM (Steering Column Control Module) detects a fault with any of the 3 inputs from the switch (circuit shorted to ground for example), the SCCM (Steering Column Control Module) sets DTC B1124:09 (Lamp Fade Control: Component Failure). The BCM (Body Control Module) then defaults the dimmable backlighting to a preset level that cannot be adjusted.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Instrument panel dimmer switch
- SCCM (Steering Column Control Module)
PINPOINT TEST B : THE COURTESY LAMPS DO NOT ILLUMINATE FROM THE INSTRUMENT PANEL DIMMER SWITCH
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
B1 CHECK THE OPERATION OF THE COURTESY LAMPS FROM A DOOR
- Place the headlamp switch in the OFF position.
- Open any door and observe the interior courtesy lamps.
Do the interior courtesy lamps illuminate?
Yes
GO to B2.
No
GO to Pinpoint Test C. Pinpoint Test C: One Or More Interior Courtesy Lamp Is Inoperative
B2 CHECK THE DIMMABLE BACKLIGHTING OPERATION
- Place the headlamp switch in the PARKING LAMPS ON position.
- Monitor the instrument panel dimmable backlighting while pressing (and holding) the instrument panel dimmer switch to the first detent up and then the first detent down.
Does the dimmable backlighting intensity change with the instrument panel dimmer switch position?
Yes
GO to B3.
No
REFER to Instrument Panel, Gauges and Warning Indicators.
B3 CHECK FOR A VOLTAGE SIGNAL TO THE INSTRUMENT PANEL DIMMER SWITCH
- Ignition OFF.
- Disconnect: Instrument Panel Dimmer Switch C2298.
- Measure the voltage between the instrument panel dimmer switch C2298-2, circuit VLN36 (GY/OG), harness side and ground.
Is the voltage approximately 5 volts?
Yes
INSTALL a new instrument panel dimmer switch. TEST the system for normal operation.
No
GO to B4.
B4 CHECK THE DOME LAMP REQUEST INPUT CIRCUIT FOR A SHORT TO VOLTAGE
- Disconnect: SCCM (Steering Column Control Module) C2414A.
- Ignition ON.
- Measure the voltage between the instrument panel dimmer switch C2298-2, circuit VLN36 (GY/OG), harness side and ground.
Is any voltage present?
Yes
REPAIR circuit VLN36 (GY/OG) for a short to voltage. TEST the system for normal operation.
No
GO to B5.
B5 CHECK THE DOME LAMP REQUEST INPUT CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between the SCCM (Steering Column Control Module) C2414A-23, circuit VLN36 (GY/OG), harness side and the instrument panel dimmer switch C2298-2, circuit VLN36 (GY/OG), harness side.
Is the resistance less than 5 ohms?
Yes
GO to B6.
No
REPAIR circuit VLN36 (GY/OG) for an open. TEST the system for normal operation.
B6 CHECK FOR CORRECT SCCM (Steering Column Control Module) OPERATION
- Disconnect all the SCCM (Steering Column Control Module) connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SCCM (Steering Column Control Module) connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new SCCM (Steering Column Control Module). 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.