System Operation
System Diagram - Conventional Ignition Switch
E362276 *.sttxt { visibility: hidden; } *.stcallout { visibility: visible; } 1 PCM 2 GWM 3 BCM 4 Ignition Switch 5 Gear Selector Lever 6 Run/Start Relay 7 Ignition Key Inhibit SolenoidItem | Description |
---|---|
1 | PCM |
2 | GWM |
3 | BCM |
4 | Ignition Switch |
5 | Gear Selector Lever |
6 | Run/Start Relay |
7 | Ignition Key Inhibit Solenoid |
Network Message Chart - Conventional Ignition Switch
GWM Module Network Input Messages
Broadcast Message | Originating Module | Message Purpose |
---|---|---|
Ignition status | BCM | This message informs the GWM of the current ignition status; off, on, start, unknown or invalid. |
PCM Module Network Input Messages
Broadcast Message | Originating Module | Message Purpose |
---|---|---|
Ignition status | BCM | This message informs the PCM of the current ignition status; off, on, start, unknown or invalid. |
Ignition Switch System
The BCM controls the ignition modes, including OFF, ACC, ON and START. This allows some systems to be activated without starting the vehicle.
The BCM provides voltage at all times to the ignition switch. Depending on the ignition switch position, voltage may be routed to one or two of the ignition switch input circuits back to the BCM .
OFF
The BCM supplies voltage to the ignition switch at all times. When the ignition switch is in the OFF position, the switch is open, preventing any voltage signals from reaching the BCM . When the BCM does not detect voltage from any of the ignition mode-designated circuits, the BCM interprets this as the ignition off mode.
The BCM communicates the ignition mode to the other modules by sending an ignition status message over the CAN and does not energize any relays to prevent 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 circuit to the BCM . The BCM interprets this as the ignition accessory mode.
The BCM communicates the ignition mode to the other modules by sending an ignition status message over the CAN and energizes the accessory designated relays and provides power to some electrical system.
ON
When the ignition switch is in the ON position, the switch routes voltage through the ACC-designated and ON-designated circuits to the BCM . The BCM interprets this as the ignition on mode.
The BCM communicates the ignition mode to the other modules by sending an ignition status message over the CAN and activates the internal run/start relay, providing ignition power to the various vehicle systems and modules.
START
When the ignition switch is placed in the START position, the switch routes voltage through the ON-designated and START-designated circuits to the BCM .
The BCM interprets this as the ignition start mode and communicates the ignition mode to the other modules by sending an ignition status message over the CAN . Additionally, the ignition switch routes voltage to the PCM indicating a request to start the vehicle.
The START-designated circuit is only used for vehicle starting.
Ignition Key Inhibit
The ignition key cylinder inhibit feature prevents the ignition lock cylinder from being rotated to the OFF/LOCK position when the vehicle is not in PARK.
The key removal inhibit solenoid (part of the ignition switch) receives battery voltage at all times from the BCM fuse 18 (5A). The ground control circuit for the key removal inhibit solenoid is routed to a park detect switch within the selector lever assembly (floor shift) or the brake shift interlock actuator (column shift).
For vehicles equipped with a floor shifter, the ground is controlled by the BCM .
For vehicles equipped with a column shifter, the park detect switch routes the signal directly to ground to activate the ignition key inhibit solenoid.
When the selector lever is in PARK, the park detect switch inside the selector lever assembly (floor shift) or the brake shift interlock actuator (column shift) is open, preventing the solenoid from actuating. When the selector lever is moved out of PARK, the switch closes and completes the circuit to the BCM (floor shifter) or to ground (column shift).
For vehicles with a floor shifter, the BCM controls the ground by means of a Field Effect Transistor (FET). The BCM enables the path to ground when it detects the vehicle is not in PARK based on messages received over the CAN .
When the selector lever is in PARK, the key removal inhibit solenoid deactivates and allows the ignition lock cylinder to be turned to the OFF/LOCK position to remove the key.
System Diagram - Push Button Ignition Switch
*.sttxt { visibility: hidden; } *.stcallout { visibility: visible; } E362282 1 PCM 2 GWM 3 Ignition Switch (Start/Stop Button) 4 Ignition Mode Indicator 5 BCM 6 Run/Start RelayItem | Description |
---|---|
1 | PCM |
2 | GWM |
3 | Ignition Switch (Start/Stop Button) |
4 | Ignition Mode Indicator |
5 | BCM |
6 | Run/Start Relay |
Network Message Chart - Push Button Ignition Switch
GWM Module Network Input Messages
Broadcast Message | Originating Module | Message Purpose |
---|---|---|
Ignition status | BCM | This message informs the GWM of the current ignition status; off, run, start, unknown or invalid. |
PCM Module Network Input Messages
Broadcast Message | Originating Module | Message Purpose |
---|---|---|
Ignition status | BCM | This message informs the PCM of the current ignition status; off, run, start, unknown or invalid. |
Push Button Ignition Switch
The push button ignition switch is used to control the ignition mode.
There are 2 circuits the BCM
monitors from the ignition switch to change the ignition mode. One
circuit is monitored for voltage and the other for a ground signal. When
the START/STOP button is pressed, one circuit routes battery voltage to
the BCM while a voltage signal from the BCM
on the second circuit is routed to ground, indicating a request to
change the ignition mode. Changing the ignition mode out of OFF works in
conjunction with the PATS . The BCM must recognize a valid programmed key before it changes the ignition mode out of OFF.
Refer
to: Passive Anti-Theft System (PATS) - System Operation and Component
Description (419-01B Passive Anti-Theft System (PATS), Description and
Operation).
Refer to the following table for information about achieving the various ignition modes.
Ignition Entry Condition | Desired Ignition Mode | Action To Take |
---|---|---|
Off | ON (engine off) | Press the START/STOP button without applying the brake pedal. |
Off or on | START | Apply the brake pedal and then press the START/STOP button. |
On (engine off) | OFF | Press the START/STOP button. |
On (engine running) | OFF | Press and hold the START/STOP button. |
Ignition Mode LED Indicator
The ignition mode LED indicates the ignition mode of the vehicle. The BCM controls the voltage to the ignition mode LED indicator. Refer to the following table.
Ignition Mode | Ignition Mode LED Indicator |
---|---|
Off | Off |
On (engine off) | Flashing |
On (engine running) | On |
OFF
The BCM 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 at a speed greater than 15 km/h (9 mph), the START/STOP button must be pressed and held for longer than one second (or pressed 3 times within 2 seconds) to turn the ignition off.
When the BCM changes the ignition mode to OFF, it communicates the ignition mode to the other modules by sending an ignition status message over the CAN .
ON
The BCM
must recognize a programmed key before it changes the ignition mode
out of OFF. When the START/STOP button is pressed when the ignition is
off, the BCM checks the vehicle for a valid programmed key as part of
the PATS function. If no valid programmed key is detected, the ignition
remains off.
Refer to: Passive Anti-Theft System (PATS) (419-01B Passive Anti-Theft System (PATS), Diagnosis and Testing).
When the ignition is in the ON mode, the BCM activates the run/start relay to provide voltage to the vehicle electrical systems and communicates the ignition mode to the other modules by sending an ignition status message over the CAN .
When the vehicle enters ON mode, multiple indicators in the IPC prove out and the IPC displays the gear selection and the vehicle mileage.
START
If the brake pedal is applied when the START/STOP button is pressed, the vehicle temporarily goes into the START mode so long as a valid programmed key is detected within the vehicle.
In addition to activating the run/start relay, the BCM communicates the ignition mode to the other modules by sending an ignition status message over the CAN .
After the ignition has completed the vehicle start sequence, the ignition mode returns to ON and the ignition mode indicator in the ignition switch illuminates steadily.
The engine can be started from any ignition mode.
System Diagram - Heated Steering Wheel
*.sttxt { visibility: hidden; } *.stcallout { visibility: visible; } 1 Heated Steering Wheel E362365 2 BCM 3 PCM 4 SCCM 5 APIM 6 FCIM 7 GWM 8 FDIM 9 IPC 10 Heating Element 11 Temperature SensorItem | Description |
---|---|
1 | Heated Steering Wheel |
2 | BCM |
3 | PCM |
4 | SCCM |
5 | APIM |
6 | FCIM |
7 | GWM |
8 | FDIM |
9 | IPC |
10 | Heating Element |
11 | Temperature Sensor |
Network Message Chart - Heated Steering Wheel
SCCM Network Input Messages
Broadcast Message | Originating Module | Message Purpose |
---|---|---|
Engine power status | PCM | This message indicates to the SCCM whether the engine is running. |
Ignition status | BCM | Indicates which ignition mode is active. |
Transport mode | BCM | Message is used to reduce the drain on the battery during long periods when the vehicle is not used, such as shipping from the factory to the dealership. |
Steering wheel heat request | FCIM | Message is used to activate the heated steering wheel function when the touchscreen button is pressed on the FDIM , or when the conditions are met to activate the heated steering wheel (and heated seats) during a remote start. |
FCIM Module Network Input Messages
Broadcast Message | Originating Module | Message Purpose |
---|---|---|
Heated steering wheel button status | APIM | This message informs the FCIM that the heated steering wheel touchscreen button was pressed on the FDIM . |
Ambient exterior temperature data | IPC | This message is used by the FCIM when determining if outside conditions are cold enough to request the heated steering wheel be activated during remote start operation. |
Heated Steering Wheel
When the SCCM receives a request to heat the steering wheel, the SCCM applies voltage and ground to the steering wheel heating elements (integral to the steering wheel) to heat the steering wheel to a temperature of approximately 28-34°C (82-94°F). The heated steering wheel temperature is maintained by the SCCM using a temperature sensor in the steering wheel.
The SCCM is designed to remain on, heating the steering wheel and maintaining the temperature until switched off on the FDIM or the ignition is turned off.
The controls and indicators for the heated steering wheel system are located on the FDIM (touchscreen) only. The FDIM does not communicate on any network and is connected directly to the APIM . The SCCM recieves signals from the FDIM and APIM via the GWM over the MS-CAN .
Remote Start System
The heated steering wheel system (along with the heated front seats) may be configured using the message center to activate when the remote start feature is used, based on outside air temperature. During remote start, the outside air temperature is continually evaluated by the HVAC system. The heated steering wheel system activation changes if the outside air changes from cold to moderate or warm temperatures or back from moderate or warm to cold temperatures.
Component Description
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 is monitored by the BCM , which controls the voltage to the various electrical systems depending on input from the ignition switch.
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/LOCK position unless the 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 a momentary dual contact switch that provides direct input to the BCM and PCM . Both sets of contacts are normally open. When the START/STOP button is pressed, one set of contacts provides a ground signal to the BCM and the other set of contacts supplies voltage to the BCM and the PCM .
The ignition mode LED indicator is located near the top of the START/STOP button and is controlled by the BCM .
SCCM
The SCCM controls the steering wheel heating elements. The SCCM uses the steering wheel temperature sensor to maintain the steering wheel temperature. The SCCM is designed to remain on, heating the steering wheel and maintaining temperature until switched off using the FDIM or the ignition is turned off.
The SCCM requires PMI when replaced.
BCM
The BCM controls the run/start relays and sets the vehicle ignition mode based on inputs from the ignition switch. It communicates the ignition mode to other modules over the CAN . If a fault is detected with the ignition switch system, Diagnostic Trouble Codes (DTCs) are set in the BCM .
The BCM requires at least 2 keys to be programmed and PMI when replaced. Additionally, the parameter reset procedure must be carried out.
Special Tool(s) / General Equipment
Wheel Alignment SystemActivation
NOTICE: Suspension fasteners are critical parts that affect the performance of vital components and systems. Failure of these fasteners may result in major service expense. Use the same or equivalent parts if replacement is necessary. Do not use a replacement part of lesser quality or substitute design. Tighten fasteners as specified.
Using alignment equipment and the manufacturer's instructions, measure the rear camber.