Pinpoint Test B: An Individual Courtesy Lamp Is Inoperative

WARNING: This page is about a different car, the 2009 Mercury Grand Marquis and 2009 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.

Refer to appropriate SYSTEM WIRING DIAGRAMS article, Interior Lamps for schematic and connector information.

Normal Operation

The lighting control module (LCM) supplies voltage to the courtesy lamps on circuit 53 (BK/LB). The courtesy lamps are grounded through circuit 57 (BK).

This pinpoint test is intended to diagnose the following:

Wiring, terminals or connectors
Interior lamp

PINPOINT TEST B: AN INDIVIDUAL COURTESY LAMP IS INOPERATIVE

B1 CHECK CIRCUIT 53 (BK/LB) FOR AN OPEN

Disconnect: Inoperative Courtesy Lamp

Measure the voltage between the inoperative courtesy lamp, harness side and ground as follows:

Location	Connector-Pin	Circuit
Front dome lamp	C978-1	53 (BK/LB)
Overhead console without roof opening panel (if equipped)	C930-7	53 (BK/LB)
Overhead console with roof opening panel (if equipped)	C9013b-14	53 (BK/LB)
LH footwell lamp	C2056-1	53 (BK/LB)
RH footwell lamp	C2057-1	53 (BK/LB)
Rear reading lamp	C932-2	53 (BK/LB)

Is the voltage greater than 10 volts?

YES : Go to B2.
NO : REPAIR the circuit. TEST the system for normal operation.

B2 CHECK CIRCUIT 57 (BK) FOR AN OPEN

Measure the resistance between the inoperative courtesy lamp, harness side and ground as follows:

Location	Connector-Pin	Circuit
Front dome lamp	C978-2	57 (BK)
Overhead console without roof opening panel (if equipped)	C930-9	57 (BK)
Overhead console with roof opening panel (if equipped)	C9013a-3	676 (PK/OG)
LH footwell lamp	C2056-2	57 (BK)
RH footwell lamp	C2057-2	57 (BK)
Rear reading lamp	C932-3	57 (BK)

Is the resistance less than 5 ohms?

YES : INSTALL a new interior lamp assembly. TEST the system for normal operation.
NO : REPAIR the circuit. TEST the system for normal operation.