Pinpoint Test A: The Control Illumination Is Inoperative - All Hardwired Illumination
Instrument Cluster and Panel Illumination
Pinpoint Tests
Pinpoint Test A: The Control Illumination Is Inoperative - All Hardwired Illumination
Refer to Wiring Diagram Set 71, Cluster and Panel Illumination for schematic and connector information. Diagrams By Number
Normal Operation
When the parking lamps are on, the Smart Junction Box (SJB) sends a pulse-width modulated voltage to the dimmable illumination sources on circuits VLN04 (VT/GY) and CLN04 (BU/BN) based on the input received from the instrument panel dimmer switch.
- DTC B2026 (Incandescent Backlighting Output Circuit Failure) - a continuous DTC that sets when the SJB detects a short to ground from the incandescent lighting output circuit.
- DTC B2027 (LED Backlighting Output Circuit Failure) - a continuous DTC that sets when the SJB detects a short to ground from the LED backlighting output circuit.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Instrument panel dimmer switch
- SJB
PINPOINT TEST A: THE CONTROL ILLUMINATION IS INOPERATIVE - ALL HARDWIRED ILLUMINATION
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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A1 CHECK FOR RECORDED SJB DTCs FROM THE SELF-TEST
- Use the recorded results from the SJB self-test.
- Is the DTC B2026 or B2027 recorded?
Yes
GO to A3.
No
GO to A2.
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A2 CHECK THE INSTRUMENT PANEL DIMMER SWITCH
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: SJB DataLogger.
- Monitor the SJB dimmer switch PID (DSWSTAT) while rotating the instrument panel dimmer switch from the lowest setting to the highest setting.
- Does the PID indicate the switch is operating correctly?
Yes
GO to A4.
No
INSTALL a new instrument panel dimmer switch. REFER to Instrument Panel Dimmer Switch Service and Repair. CLEAR the DTCs. REPEAT the self-test.
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A3 CHECK THE ILLUMINATION OUTPUT CIRCUITS VLN04 (VT/GY) AND CLN04 (BU/BN)
NOTE: If the fuse in the jumper wire fails, refer to the Wiring Diagrams to identify the possible causes of the short circuit.
- Ignition OFF.
- Disconnect: SJB C2280d.
- Connect a fused jumper wire between the SJB C2280d-2, circuit VLN04 (VT/GY), harness side and battery; or between the SJB C2280d-3, circuit CLN04 (BU/BN), harness side and battery.
- Do the backlighting components illuminate?
Yes
REMOVE the jumper wire. GO to A4.
No
REMOVE the jumper wire. REPAIR the circuit. RUN the self-test (required to clear certain DTCs). CORRECT any unresolved DTCs. CLEAR all DTCs. TEST the system for normal operation.
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A4 CHECK FOR CORRECT SJB OPERATION
- Disconnect all the SJB connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SJB 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 SJB. REFER to Body Control Systems. 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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