Pinpoint Test A: The Courtesy Lamps Are Inoperative

Interior Lighting

Pinpoint Tests

Pinpoint Test A: The Courtesy Lamps Are Inoperative

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

Normal Operation

The Smart Junction Box (SJB) fuse 3 (15A) supplies voltage to the courtesy lamps relay, the demand lamps relay (Fusion, Milan only), and the courtesy lamps Field-Effect Transistor (FET) (MKZ only). When the SJB detects a request from the instrument panel dimmer switch, a door or the luggage compartment lid is open, the SJB supplies voltage to the courtesy lamps on circuit CLN26 (BU). Ground for the courtesy lamps is supplied through circuit GD139 (BK/YE) or circuit GD126 (BK/WH).

- DTC B2499 (Courtesy Lamp Output Failure) - a continuous DTC that sets when the SJB detects a short to ground from the courtesy lighting output circuit. This DTC applies to MKZ only.

This pinpoint test is intended to diagnose the following:

- Fuse
- Wiring, terminals or connectors
- SJB



PINPOINT TEST A: THE COURTESY LAMPS ARE INOPERATIVE

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

NOTE: Failure to disconnect the battery when instructed will result in false resistance readings. Refer to Battery.

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A1 CHECK CIRCUIT CLN26 (BU) FOR AN OPEN


- Ignition OFF.
- Disconnect: SJB C2280e.
- NOTE: If the fuse fails, repair circuit CLN26 (BU) for a short to ground. For MKZ, clear the DTCs and repeat the self-test after the repair.
- Connect a fused jumper wire between the SJB C2280e-16, circuit CLN26 (BU), harness side and battery positive.




- Do the courtesy lamps illuminate?

Yes
REMOVE the jumper wire. VERIFY the SJB fuse 3 (15A) is OK. If OK, GO to A3. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short.

No
REMOVE the jumper wire. VERIFY the SJB fuse 3 (15A) is OK. If OK, GO to A2. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short.

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A2 CHECK CIRCUIT GD139 (BK/YE) FOR AN OPEN


- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Disconnect: Front Interior Lamp C930.
- Measure the resistance between the front interior lamp C930-1, circuit GD139 (BK/YE), harness side and ground.




- Is the resistance less than 5 ohms?

Yes
REPAIR circuit CLN26 (BU) for an open. TEST the system for normal operation.

No
REPAIR the circuit. TEST the system for normal operation.

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A3 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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