Pinpoint Test C: All Dimmable Switch Illumination Is Always On

Instrument Cluster and Panel Illumination

Pinpoint Test C: All Dimmable Switch Illumination Is Always On

Refer to Wiring Diagram Set 71, Cluster and Panel Illumination for schematic and connector information. [1][2]Diagrams By Number

Normal Operation

When the parking lamps are on, the Smart Junction Box (SJB) sends a Pulse Width Modulated (PWM) voltage to the hardwired dimmable illumination sources based on the input received from the instrument panel dimmer switch.

- DTC B2A32 (LED Backlighting Output Circuit Open)- an on-demand DTC that sets when the SJB (Smart Junction Box) detects a short to voltage from the backlighting output circuit.

- DTC B29B7 (White Lighting Output Circuit Open)- an on-demand DTC that sets when the SJB (Smart Junction Box) detects a short to voltage from the white lighting (backlighting) output circuit.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors

- SJB (Smart Junction Box)

PINPOINT TEST C : ALL DIMMABLE SWITCH ILLUMINATION IS ALWAYS ON

NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.

C1 CHECK THE EXTERIOR LIGHTING

- Ignition ON.

- Observe the exterior lighting components.

Are any exterior lighting components illuminated?

Yes
REFER to Lighting and Horns.

No
GO to C2.

C2 CHECK THE SJB (Smart Junction Box) BACKLIGHTING OUTPUT CIRCUIT FOR A SHORT TO VOLTAGE

- Ignition OFF.

- Disconnect: SJB (Smart Junction Box) C2280B.

- Ignition ON.

Do the dimmable backlighted components continue to illuminate?

Yes
REPAIR circuit VLN04 (VT/GY) (Fusion) or circuit VLN37 (BU/WH) (MKZ) for a short to voltage. CLEAR the DTCs. REPEAT the self-test.

No
GO to C3.

C3 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.