Pinpoint Test B: All Dimmable Illumination Does Not Dim
Instrument Cluster and Panel Illumination
Pinpoint Test B: All Dimmable Illumination Does Not Dim
Refer to Wiring Diagrams Set 71, Cluster and Panel Illumination for schematic and connector information. Electrical Diagrams
Normal Operation
The Smart Junction Box (SJB) monitors the input from the instrument panel dimmer switch by sending a voltage signal to the instrument panel dimmer switch. The return signal is sent back to the SJB (Smart Junction Box). Based on the input from the instrument panel dimmer switch, the SJB (Smart Junction Box) sends a Pulse Width Modulated (PWM) voltage to the dimmable illumination sources. If the SJB (Smart Junction Box) detects a concern with the circuitry to the instrument panel dimmer switch, the SJB (Smart Junction Box) defaults the backlighting to a full intensity level.
The SJB (Smart Junction Box) also sends a message over the Controller Area Network (CAN) to the Front Controls Interface Module (FCIM) (vehicles without navigation), the Front Display Interface Module (FDIM) (vehicles without navigation), the HVAC module (vehicles with navigation), the Audio Control Module (ACM) (vehicles with navigation), the Rear Entertainment Module (RETM) (if equipped) and the Instrument Cluster (IC) to indicate the backlighting intensity level. If the receiving module receives invalid backlighting data from the SJB (Smart Junction Box) for 5 seconds or less, the receiving module defaults the backlighting to the last setting.
If the receiving module does not receive the backlighting status message from the SJB (Smart Junction Box) or if the data received is deemed invalid for more than 5 seconds, the receiving module sets DTC U0140 in continuous memory (except the HVAC module) and defaults the backlighting to full nighttime intensity.
- DTC B2212 (Panel Dim Switch Out Of Range)- an on-demand DTC that sets when the SJB (Smart Junction Box) detects an open or short to voltage on the dimmer switch input circuit.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Instrument panel dimmer switch
- SJB (Smart Junction Box)
PINPOINT TEST B : ALL DIMMABLE ILLUMINATION DOES NOT DIM
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 EXTERIOR LIGHTING OPERATION
- Place the headlamp switch in each of its positions while observing the exterior lamps.
Do the exterior lamps operate correctly?
Yes
GO to B2.
No
REFER to Lighting and Horns.
B2 CHECK THE INSTRUMENT PANEL DIMMER SWITCH
- Ignition OFF.
- Disconnect: Instrument Panel Dimmer Switch C2065.
- Carry out the component test for the instrument panel dimmer switch.
Is the instrument panel dimmer switch OK?
Yes
GO to B3.
No
INSTALL a new instrument panel dimmer switch. REFER to Instrument Panel Dimmer Switch . TEST the system for normal operation.
B3 CHECK THE INSTRUMENT PANEL DIMMER SWITCH INPUT CIRCUIT FOR A SHORT TO VOLTAGE
- Disconnect: SJB (Smart Junction Box) C2280B.
- Start the engine.
- Measure the voltage between the instrument panel dimmer switch C2065-6, circuit VLN18 (BU/WH), harness side and ground.
Is any voltage present?
Yes
REPAIR circuit VLN18 (BU/WH) for a short to voltage. TEST the system for normal operation.
No
GO to B4.
B4 CHECK THE INSTRUMENT PANEL DIMMER SWITCH RETURN CIRCUIT FOR A SHORT TO VOLTAGE
- Measure the voltage between the instrument panel dimmer switch C2065-4, circuit RLN29 (WH/OG), harness side and ground.
Is any voltage present?
Yes
REPAIR circuit RLN29 (WH/OG) for a short to voltage. TEST the system for normal operation.
No
GO to B5.
B5 CHECK THE INSTRUMENT PANEL DIMMER SWITCH INPUT CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between the instrument panel dimmer switch C2065-6, circuit VLN18 (WH/BN), harness side and ground.
Is the resistance greater than 10,000 ohms?
Yes
GO to B6.
No
REPAIR circuit VLN18 (BU/WH) for a short to ground. TEST the system for normal operation.
B6 CHECK THE INSTRUMENT PANEL DIMMER SWITCH INPUT CIRCUIT FOR AN OPEN
- Measure the resistance between the instrument panel dimmer switch C2065-6, circuit VLN18 (BU/WH), harness side and the SJB (Smart Junction Box) C2280B-34, circuit VLN18 (BU/WH), harness side.
Is the resistance less than 5 ohms?
Yes
GO to B7.
No
REPAIR circuit VLN18 (BU/WH) for an open. TEST the system for normal operation.
B7 CHECK THE INSTRUMENT PANEL DIMMER SWITCH RETURN CIRCUIT FOR AN OPEN
- Measure the resistance between the instrument panel dimmer switch C2065-4, circuit RLN29 (WH/OG), harness side and the SJB (Smart Junction Box) C2280B-33, circuit RLN29 (WH/OG), harness side.
Is the resistance less than 5 ohms?
Yes
GO to B8.
No
REPAIR circuit RLN29 (WH/OG) for an open. TEST the system for normal operation.
B8 CHECK FOR CORRECT SJB (Smart Junction Box) OPERATION
- Disconnect all the SJB (Smart Junction Box) connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SJB (Smart Junction Box) 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 (Smart Junction Box). 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.