Pinpoint Test F: An Individual Demand 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 power to the demand lamps through circuit 705 (LG/OG). The demand lamps are grounded through circuit 57 (BK). The demand lamps remain powered until the battery feature times out. Once that timeout has been reached, then the LCM removes voltage from circuit 705 (LG/OG).

This pinpoint test is intended to diagnose the following:

Wiring, terminals or connectors
Courtesy lamp

PINPOINT TEST F: AN INDIVIDUAL DEMAND 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.

F1 CHECK CIRCUIT 705 (LG/OG) FOR AN OPEN

Key in OFF position.
Disconnect: Inoperative Demand Lamp

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

Inoperative Demand Lamp	Connector-Pin	Circuit
Front courtesy/map lamp assembly	C929-3 and C929-6	705 (LG/OG)
LH vanity mirror	C907-2	705 (LG/OG)
RH vanity mirror	C906-2	705 (LG/OG)
LH vanity mirror (rear)	C950a-1	705 (LG/OG)
RH vanity mirror (rear)	C952a-1	705 (LG/OG)
LH rail lamp	C941-3	705 (LG/OG)
RH rail lamp	C942-3	705 (LG/OG)

Is the voltage greater than 10 volts?

YES : Go to F2.
NO : REPAIR the circuit in question. TEST the system for normal operation.

F2 CHECK CIRCUIT 57 (BK) FOR AN OPEN

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

Suspect Demand Lamp	Connector-Pin	Circuit
Front courtesy/map lamp assembly	C929-4	57 (BK)
LH vanity mirror	C907-1	57 (BK)
RH vanity mirror	C906-1	57 (BK)
LH vanity mirror (rear)	C950b-1	57 (BK)
RH vanity mirror (rear)	C952b-1	57 (BK)
LH rail lamp	C941-2	57 (BK)
RH rail lamp	C942-2	57 (BK)

Is the resistance less than 5 ohms?

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