Pinpoint Test B: An Individual Courtesy Lamp Is Inoperative

WARNING: This page is about a different car, the 2010 Lincoln Town Car. 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) provides 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

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

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

Disconnect the inoperative courtesy lamp.

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

Location	Connector-Pin	Circuit
Front dome lamp	C929-5	53 (BK/LB)
LH footwell lamp	C2056-1	53 (BK/LB)
RH footwell lamp	C2057-1	53 (BK/LB)
LH rear reading lamp	C941-1	53 (BK/LB)
RH rear reading lamp	C942-1	53 (BK/LB)
LH front door lamp	C506-1	53 (BK/LB)
RH front door lamp	C606-1	53 (BK/LB)
LH rear door lamp	C713-1	53 (BK/LB)
RH rear door lamp	C812-1	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	C929-4	57 (BK)
LH footwell lamp	C2056-2	57 (BK)
RH footwell lamp	C2057-2	57 (BK)
LH rear reading lamp	C941-2	57 (BK)
RH rear reading lamp	C942-2	57 (BK)
LH front door lamp	C506-2	57 (BK)
RH front door lamp	C606-2	57 (BK)
LH rear door lamp	C713-2	57 (BK)
RH rear door lamp	C812-2	57 (BK)

Is the resistance less than 5 ohms?

YES : INSTALL a new courtesy lamp assembly for the one in question. TEST the system for normal operation.
NO : REPAIR the circuit. TEST the system for normal operation.