Pinpoint Test A: No Power in All Ignition Switch Positions

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, Power Distribution for schematic and connector information.

Normal Operation

Fused battery voltage is provided to the ignition switch from battery junction box (BJB) fuse 1 (30A) along circuit 1050 (LG/VT). The ignition switch then provides power to the central junction box (CJB) and the lighting control module (LCM) through several different circuits depending on the ignition switch position. The ignition switch has 4 possible positions:

OFF - No power on any circuits
ACC - Power on circuit 296 (WH/VT)
RUN - Power on circuits:
- 296 (WH/VT)
- 1717 (VT/OG)
- 687 (GY/YE)
START - Power on circuits:
- 1522 (DG)
- 1717 (VT/OG)

This pinpoint test is intended to diagnose the following:

Fuse(s)
Wiring, terminals or connectors
Ignition switch

PINPOINT TEST A: NO POWER IN ALL IGNITION SWITCH POSITIONS

NOTE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multi-meter probes.

A1 CHECK FOR VOLTAGE TO THE IGNITION SWITCH
- Key in OFF position.
- Disconnect: Ignition Switch C250
- Measure the voltage between ground and:
  - ignition switch C250-8, circuit 1050 (LG/VT), harness side.
  - ignition switch C250-9, circuit 1050 (LG/VT), harness side.
- Are the voltages greater than 10 volts?
1. YES : Go to A2.
2. NO : VERIFY BJB fuse 1 (30A) is OK. If OK, REPAIR circuit 1050 (LG/VT). TEST the system for normal operation.
A2 CHECK THE IGNITION SWITCH
- Carry out the Ignition Switch - Electrical Test under Component Tests .
- Is the ignition switch OK ?
1. YES : Go to A3.
2. NO : INSTALL a new ignition switch. REFER to Ignition Switch . TEST the system for normal operation.
A3 CHECK FOR VOLTAGE TO BJB FUSE 1 (30A)
- Measure the voltage between BJB fuse 1 (30A), input side and ground.
- Is the voltage greater than 10 volts ?
1. YES : VERIFY BJB fuse 1 (30A) is OK. If OK, REPAIR circuit 1050 (LG/VT). TEST the system for normal operation.
2. NO : Go to A4.
A4 CHECK FOR VOLTAGE TO THE BJB
- Measure the voltage between BJB C1035 eyelet, circuit 2037 (RD) and ground.
- Is the voltage greater than 10 volts ?
1. YES : INSTALL a new BJB. TEST the system for normal operation.
2. NO : REPAIR circuit 2037 (RD). TEST the system for normal operation.