Steering Column Switches: Overview Ford Escape II

The steering column switches consist of the following

1. Ignition switch
2. Multifunction switch

The ignition switch is mounted to the LH side of the steering column and is used in conjunction with the ignition lock cylinder key and steering column lock module to start the vehicle. When the lock cylinder key is switched to different positions, it moves a mechanical link in the steering column lock module, which enables the ignition switch to send battery voltage to various components.

The integrated multifunction switch is also mounted to the LH side of the steering column and controls the high beam/low beam, flash-to-pass, turn signals, hazard flashers and windshield wiper switches.

Principles of Operation

Note. The Smart Junction Box (SJB) is also identified as the Generic Electronic Module (GEM).

The steering column switches include the ignition switch and the multifunction switch (high beam/low beam, flash-to-pass, turn signal and windshield wiper).

Normal Operation

The ignition switch receives fused battery voltage along circuit SBP27 (BU/RD) from Smart Junction Box (SJB) fuse 27 (20A). The ignition switch then sends that voltage out to various systems depending on ignition switch position. The ignition switch has 4 possible states

1. OFF - No power on any circuits
2. ACC - Power on circuit CDC33 (VT/GN)
3. RUN - Power on circuits CDC33 (VT/GN) and CDC34 (WH/OG)
4. START - Power on circuit CDC34 (WH/OG), CDC35 (BU/WH) and CDC54 (WH/GN) (non-hybrid vehicles)

This pinpoint test is intended to diagnose the following

1. Fuse
2. Wiring, terminals or connectors
3. Ignition switch
4. SJB

When the ignition switch is placed in ACC, fused ignition voltage is sent to the Smart Junction Box (SJB) along circuit CDC33 (VT/GN).

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Ignition switch
3. SJB

When the ignition switch is placed in RUN, fused ignition voltage is sent to the

1. Smart Junction Box (SJB).
2. Battery Junction Box (BJB).
3. PCM.

This pinpoint test is intended to diagnose the following

1. Fuse(s)
2. Wiring, terminals or connectors
3. Ignition switch
4. SJB
5. PCM

When the ignition switch is placed in START, fused ignition voltage is sent to the

1. Battery Junction Box (BJB) fuse 35 (10A)
2. Smart Junction Box (SJB)
3. PCM

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Ignition switch
3. SJB
4. One-Touch Integrated Start (OTIS) diode
5. PCM

The ignition switch is spring-loaded to automatically return to the RUN position after being placed in the START position. A microprocessor in the Smart Junction Box (SJB) monitors the voltage output from the ignition switch while the switch is in the START position. This microprocessor is also connected to the Audio Control Module (ACM) start circuit, so a short to voltage on the ignition switch output circuit or on the ACM start circuit could cause DTC B2A20 to set.

1. B2A20 (Ignition Stuck in START) - The SJB continuously monitors the ignition switch state, if the SJB receives a START signal for more than 30 seconds, DTC B2A20 will be set.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Ignition switch
3. SJB
4. PCM
5. ACM
6. Starter relay

The Smart Junction Box (SJB) contains several microprocessors that monitor the voltage outputs from the ignition switch. The SJB uses these inputs to determine the ignition switch position and then sends that information to various modules over the High Speed Controller Area Network (HS-CAN) bus.

1. DTC B2844 (Ignition Fault) - If the SJB receives an invalid ignition RUN input or cannot receive the ignition RUN input during normal operation, DTC B2844 is set.
2. DTC U2472 (Unexpected Ignition State) - If the SJB does not receive the ignition RUN signal or receives conflicting ignition switch signals while performing an on-demand self test, DTC U2472 is set.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Ignition switch
3. SJB

The key removal inhibit solenoid (part of the ignition switch) receives battery voltage from Smart Junction Box (SJB) fuse 27 (20A) through circuit SBP27 (BU/RD). When the selector lever is moved out of the PARK position, the park range switch (part of the selector lever) closes and connects circuit CDC41 (WH/BN) to circuit GD112 (BK/GN), providing ground to the key removal inhibit solenoid. The key removal inhibit solenoid activates and prevents the ignition lock cylinder from being turned to the OFF position and the key removed.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Ignition switch
3. Ignition lock cylinder
4. Selector lever
5. Steering column lock module

The key removal inhibit solenoid (part of the ignition switch) receives battery voltage from Smart Junction Box (SJB) fuse 27 (20A) through circuit SBP27 (BU/RD). When the selector lever is moved out of the PARK position, the park range switch (part of the selector lever) closes and connects circuit CDC41 (WH/BN) to circuit GD112 (BK/GN), providing ground to the key removal inhibit solenoid. The key removal inhibit solenoid activates and prevents the ignition lock cylinder from being turned to the OFF position and the key removed.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Ignition switch
3. Selector lever

See also:
• SUPPLEMENTAL RESTRAINT SYSTEM