Power Mode Description and Operation
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Power Mode Description and Operation
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Serial Data Power Mode Master
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Power to many of this vehicles circuits is controlled by the module that is designated the power mode master. The main control module for current mode is the BCM. The ignition switch is a low current switch with multiple discrete ignition switch signals to the power mode master for determination of the power mode that will be sent over the serial data circuits to the other modules that need this information. The power mode master will also activate relays and other direct outputs of the power mode master as needed. The power mode master determines which power mode (Off, Accessory, Run, Crank Request) is required, and reports this information to other modules via serial data. Modules which have switched voltage inputs may operate in a default mode if the power mode serial data message does not match what the individual module can see from its own connections.
The power mode master receives ignition switch signals to identify the operators desired power mode. The Power Mode Parameters table below illustrates the correct state of these input parameters (circuits) in correspondence to the ignition switch position:
Power Mode Parameters
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Ignition Switch Position
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Power Mode Trans- mitted
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Ignition Off/Run/Crank
(Off / Run Crank Voltage Circuit)
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Ignition Accessory / Run
(Accessory Voltage Circuit)
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Ignition Run/ Crank
(Ignition 1 Voltage Circuit)
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Off Key Out
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Off
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Key Out/ ACC
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Inactive
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Inactive
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Off Key IN
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Off
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Key In/Off
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Inactive
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Inactive
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Acces-sory
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Acces-sory
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Key Out/ ACC
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Active
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Inactive
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Run
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Run
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Run
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Active
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Active
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Starting
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Crank Request
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Crank
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Inactive
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Active
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Relay Controlled Power Mode
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The BCM uses the discrete ignition switch inputs Off/Run/Crank Voltage, Accessory Voltage, and Ignition 1 Voltage, to distinguish the correct power mode. The BCM, after determining the desired power mode, will activate the appropriate relays for that power mode.
The retained accessory power relay remains on for a timed period after the Ignition key is removed. Refer to
Retained Accessory Power Description and Operation
for more information on the retained accessory power function.
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Button start (certain variants)
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The ignition mode switch has 2 LED"s that indicate the vehicle power mode. When the vehicle is in the off mode, both LED"s will be off. Pressing the ignition mode switch button once (without the brake pedal applied), the vehicle enters the accessory mode and the amber LED (ACC) will illuminate. The accessory mode has a 5 minute timeout to reduce battery drain. When you press the start button a second time (without brake pedal depressed) the car moves to drive/start mode(without the engine running) and the green lamp (driving/start) lights. If the start button is pressed and held in for at least 5 seconds the car moves to driving/start mode (without the engine running) and the green lamp (driving/start) lights. With ignition OFF (with the brake pedal pressed), one push of the start button and the car moves to driving/start mode (without the engine running) and the green lamp (driving/start) lights. This will start the engine. Both LEDs receive current from the BCM. The ignition mode switch sends the ignition mode switch status to the passive entry passive start module (PEPS) and to the BCM. The PEPS module sends a redundant signal to the BCM with the ignition mode switch status.
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Battery save mode (certain variants)
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The battery saver mode reduces the parasitic load of some modules during overseas shipment or during vehicle storage conditions. Thanks to this the battery drain time is extended (up to 70 days without complete discharge). When the car is transported/is in storage certain functions are restricted as a result of the battery being in save mode, for example. disengaging the remote control function actuators or anti-theft alarm function.
The battery saver mode incorporates a latching relay that when enabled disconnects some modules from their ignition off power or memory power sources. Battery save mode is initiated when the hazard warning lights are activated, the car is started and the ignition key is turned to start position or the start button is pressed (where applicable) for more than 15 seconds. The mode is disengaged by repeating the previous process causing the relay to latch in the other direction. This feature can be used as many times as necessary if the vehicle is to be stored for an extended period of time.
The BCM is able to control or perform all of the BCM functions in the awake state. The BCM enters the sleep state when active control or normal monitoring of system functions has stopped and a time limit has passed. The BCM must detect certain wake-up inputs before entering the awake state. The BCM monitors for these inputs during the sleep state.
The BCM will enter the awake state if any of the following wake-up inputs are detected:
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Activity on the serial data line
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Detection of a battery reconnect
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Keyless entry or remote start message
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The BCM will enter a sleep state when all of the following conditions exist:
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The ignition switch is OFF, key out.
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No activity exists on the serial data line.
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No outputs are commanded.
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No delay timers are actively counting.
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No wake-up inputs are present.
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If all these conditions are met, the BCM will enter a low power or sleep condition.
