Pinpoint Test B: The Courtesy Lamp Is Inoperative From The Instrument Panel Dimmer Switch

Interior Lighting

Pinpoint Test B: The Courtesy Lamp Is Inoperative From The Instrument Panel Dimmer Switch

Refer to Wiring Diagram Set 89, Interior Lamps for schematic and connector information [1][2]Diagrams By Number.

Normal Operation

The Smart Junction Box (SJB) monitors the instrument panel dimmer switch status to determine if the courtesy lamp is requested. Based on the instrument panel dimmer switch status, the SJB (Smart Junction Box) supplies voltage to the courtesy lamp.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors

- Instrument panel dimmer switch

- SJB (Smart Junction Box)

PINPOINT TEST B : THE COURTESY LAMP IS INOPERATIVE 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 DIMMABLE BACKLIGHTING OPERATION

- Place the headlamp switch in the PARKLAMP position.

- Monitor the instrument panel dimmable backlighting while rotating the instrument panel dimmer switch from full on to full off.

Does the dimmable backlighting intensity change with the instrument panel dimmer switch position?

Yes
GO to B2.

No
REFER to Instrument Panel, Gauges and Warning Indicators.

B2 CHECK THE INSTRUMENT PANEL DIMMER SWITCH

- Ignition OFF.

- Disconnect: Instrument Panel Dimmer Switch C2298.

- Connect a fused jumper wire between the instrument panel dimmer switch C2298-2, circuit CLN28 (GN/BU), harness side and the instrument panel dimmer switch C2298-4, circuit RLN29 (WH/OG), harness side.





Does the courtesy lamp illuminate?

Yes
REMOVE the jumper wire. INSTALL a new instrument panel dimmer switch. TEST the system for normal operation.

No
REMOVE the jumper wire. GO to B3.

B3 CHECK THE DOME LAMP REQUEST INPUT CIRCUIT FOR AN OPEN

- Disconnect: SJB (Smart Junction Box) C2280B.

- Measure the resistance between the SJB (Smart Junction Box) C2280B-51, circuit CLN28 (GN/BU), harness side and the instrument panel dimmer switch C2298-2, circuit CLN28 (GN/BU), harness side.





Is the resistance less than 5 ohms?

Yes
GO to B4.

No
REPAIR circuit CLN28 (GN/BU) for an open. TEST the system for normal operation.

B4 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.