Steering Wheel and Column Electrical Components - System Operation and Component Description

System Operation

System Diagram - Conventional Ignition Switch

Conventional Ignition Switch System

The ignition switch controls the ignition states, including OFF, ACC, ON and START. This allows some systems to be activated without starting the vehicle.

OFF

The CJB supplies voltage to the ignition switch. When the ignition switch is in the OFF position, the switch is open, preventing voltage from being distributed to the various electrical systems.

ACC

When the ignition switch is in the ACC position, the switch routes voltage through the ACC-designated circuitry to various vehicle electrical components such as the IPC , the BCM and the CJB to power up specific vehicle systems. This allows functionality of specific electrical systems without placing additional current drain on the battery from the powertrain electrical system when the vehicle is not running.

ON

When the ignition switch is in the ON position, the switch routes voltage through the ACC-designated and ON-designated circuitry to power all the vehicle electrical systems.

START

When the ignition switch is in the START position, the switch routes voltage through the ON-designated circuitry and a separate circuit to the IPC and the PCM to start the vehicle. The circuit designated for the START mode is only used for vehicle starting.

Ignition Key Inhibit

On vehicles with an automatic transmission, the ignition key cylinder inhibit feature prevents the ignition lock cylinder from being rotated to the OFF position when the vehicle is not in PARK.

Battery voltage is supplied to the inhibit solenoid within the ignition switch. A switch within the floor shifter controls the ground side of the inhibit solenoid. When the floor shifter is in PARK, the switch is open, allowing the ignition lock cylinder to rotate through all its positions. When the floor shifter is moved out of PARK, the switch closes and the ignition key inhibit solenoid energizes to prevent the ignition lock cylinder and ignition switch from rotating to the OFF position. This also prevents the key from being removed from the ignition lock cylinder.

System Diagram - Push Button Start

Push-Button Start System

The START/STOP button (ignition switch) is used to control the ON, OFF and START ignition modes.

The RFA module sends 2 voltage signals to the push-button ignition switch to monitor requests to turn the ignition on, off or to start the vehicle. When the button is pressed, the voltage signals are routed to ground indicating a request to change the ignition state. Changing the ignition state from the OFF mode works in conjunction with the PATS . A programmed key is required to change the ignition from OFF to ON. For additional PATS information,
Refer to: Passive Anti-Theft System (PATS) - System Operation and Component Description (419-01C Passive Anti-Theft System (PATS) - Vehicles With: Keyless Entry and Push Button Start, Description and Operation).

The RFA module provides voltage to the same circuits a conventional ignition switch does by using additional relays to achieve 2 of the 3 standard ignition states (ON and START). Unlike a conventional ignition switch system, the push-button start system does not have an ACC mode. The RFA module only utilizes the OFF, ON and START modes.

Refer to the following table for information about achieving the various ignition states.

The RFA module must recognize a programmed key before it changes the ignition state from OFF.

OFF

The RFA module controls the relays providing voltage to the vehicle electrical systems. When the ignition is in the ON mode, a single press and release of the START/STOP button changes the ignition to the OFF mode. No programmed key is required to change the ignition to the OFF mode when the vehicle is running.

If the vehicle is in motion, a momentary press of the START/STOP button does not shut the vehicle off. If the vehicle is moving, the START/STOP button must be pressed and held for longer than one second to turn the ignition off.

ON

The RFA module must recognize a programmed key before it changes the ignition state out of OFF. When the START/STOP button is pressed when the ignition is off, the RFA module checks the vehicle for a programmed key as part of the PATS function. If no programmed key is detected, the ignition remains off. For additional PATS information,
Refer to: Passive Anti-Theft System (PATS) - System Operation and Component Description (419-01C Passive Anti-Theft System (PATS) - Vehicles With: Keyless Entry and Push Button Start, Description and Operation).

When the ignition is in the ON mode, the RFA module activates the smart keyless entry relays to provide voltage to the vehicle electrical systems.

When the vehicle enters ON mode, multiple indicators in the IPC prove out and the IPC displays the gear selection (automatic transmission) and the vehicle mileage.

START

When the clutch is fully applied (manual transmission) or the brake pedal is applied (automatic transmission) when the START/STOP button is pressed , the vehicle temporarily goes into the START mode until the vehicle starts (so long as a programmed key is detected within the vehicle).

In addition to activating the smart keyless entry relays, the RFA module provides voltage through a separate circuit to the PCM to start the vehicle. This circuit is only used for vehicle starting.

FCDIM Messages

The FCDIM can display messages to indicate a potential concern with the push-button start system. The following FCDIM messages pertaining to the push-button start system are:

• TO START PRESS BRAKE — Momentarily displays when the START/STOP button is pressed without the brake pedal applied (automatic transmission).
• TO START SELECT N OR P — Displays when attempting to start the vehicle and the transmission is not in NEUTRAL or PARK (automatic transmission).
• TO START PRESS CLUTCH — Momentarily displays when the START/STOP button is pressed without the clutch pedal fully applied (manual transmission).
• VEHICLE NOT IN PARK SELECT P — Displays when the START/STOP button is pressed to turn off the vehicle with the transmission in any position other than PARK (automatic transmission).
• KEY NOT DETECTED — Displays when the RFA module searches for a passive key inside the vehicle and no programmed key is detected.
  Refer to: Passive Anti-Theft System (PATS) - System Operation and Component Description (419-01C Passive Anti-Theft System (PATS) - Vehicles With: Keyless Entry and Push Button Start, Description and Operation).
  

Component Description

Multifunction Switches

The multifunction switches are used to control various systems (high beam headlamps, flash-to-pass, turn signal, trip computer display and windshield wiper/washer) by grounding various input circuits to BCM or the IPC . When the BCM or IPC detects the ground signal, the appropriate system function activates. The BCM controls the exterior lighting and the windshield wipers/washers. The IPC controls the trip computer display.

• Left multifunction switch - mounted to the left side of the steering column and provides control for the trip computer display (if equipped), the turn signals, the low/high beams and the flash-to-pass function. For additional information regarding the exterior lighting,
  Refer to: Exterior Lighting - System Operation and Component Description (417-01 Exterior Lighting, Description and Operation).
  
• Right multifunction switch - mounted on the right side of the steering column and provides control for the windshield wipers and washers and the rear window wiper and washer. For additional information regarding the wipers and washers,
  Refer to: Wipers and Washers - System Operation and Component Description (501-16 Wipers and Washers, Description and Operation).
  

Steering Wheel Switches

The steering wheel switches are comprised of an upper and lower switch cluster mounted on each side of the steering wheel, facing the driver. The upper and lower switch clusters are integrated into a single switch and cannot be serviced separately.

• Left steering wheel switch - mounted on the left side of the steering wheel and provides control for the audio system. For additional information regarding the audio system, Refer to the appropriate section in Group 415 for the procedure.
• Right steering wheel switch - mounted on the right side of the steering wheel and provides control for the cruise control system. For additional information regarding the cruise control system,
  Refer to: Cruise Control - System Operation and Component Description (419-03 Cruise Control, Description and Operation).
  

Conventional Ignition Switch

The ignition switch is a multiple position rotary switch that is controlled by a lock cylinder and a key. The ignition switch provides voltage to the various electrical systems depending on the position it is placed.

The key removal inhibit solenoid (internal to the ignition switch) is an electronically controlled solenoid that prevents the ignition lock cylinder from being turned to the OFF position unless the gear selector lever is in the PARK position. This also prevents the key from being removed from the ignition lock cylinder.

Push-Button Ignition Switch

The push-button ignition switch is used instead of a conventional ignition switch to achieve the various ignition modes. The push-button ignition switch is a momentary dual contact switch. Both sets of contacts are normally open and receive voltage at all times. When the START/STOP button is pressed, the voltage signals sent from the RFA module are routed to ground, pulling the signals low to indicate a button press.

The ignition switch has a LED for switch illumination when the backlighting is activated.

RFA Module

The RFA module controls all of the ignition modes.

The RFA module requires PMI when replaced.

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