SRX RWD V8-4.6L VIN A (2006)
Body Control Module: Description and Operation
Body Control System
BODY CONTROL SYSTEM DESCRIPTION AND OPERATION
The body control system consists of the following 2 modules:
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The dash integration module (DIM)
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The rear integration module (RIM)
Each of the 2 body control modules integrate a number of functional systems. Each module is connected to the class 2 serial data circuit, many of the
control signals are implemented by class 2 messages.
Dash Integration Module (DIM)
The various dash integration module (DIM) input and output circuits are described in the corresponding functional areas as indicated on the DIM
electrical schematics.
The DIM functions include the following:
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Cigar lighter relay control
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Class 2 communication requiring DIM interaction
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Exterior lighting control
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Headlamp washer control
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Hood ajar switch input w/export
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Horn relay control
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Interior lighting control
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Load management
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Low side temperature for HVAC compressor
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Park key lock output
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Power moding control over class 2 serial data circuit
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Reverse lockout solenoid control
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Steering wheel controls input
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Storage of the clock settings and sending a message out on the class 2 serial data circuit in response to requests from other modules
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Storage of vehicle options and configuration
Power Mode
The dash integration module (DIM) is the power mode master (PMM). Refer to Power Mode Description and Operation for more information.
Electrical Load Management
The power management function is designed to monitor the vehicle electrical load and determine when the battery is potentially in a high discharge
condition. This is accomplished by using a high accuracy battery voltage reading as an indicator of battery discharge rate. The following 6 levels of
load management will execute in the load management control algorithm when there is a high discharge condition:
1. The first action requests a vehicle idle speed increase to the engine control module (ECM) in order to raise alternator output.
2. The second action requests a greater vehicle idle speed increase to the ECM in order to raise alternator output.
3. The third action begins to shed vehicle loads in an attempt to remedy the heavy discharge condition.
4. The fourth action requests another vehicle idle speed increase to the ECM in order to raise further the alternator output.
5. The fifth action begins to shed further vehicle loads in an attempt to remedy the heavy discharge condition.
6. If the above 5 corrective actions fail, the sixth action of power management further sheds loads in a final attempt to remedy the high discharge
condition.
Loads subject to reduction include the following:
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The A/C clutch
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The heated mirrors
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The heated seats
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The rear defog
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The HVAC blowers
The power mode master (PMM) calculates the battery temperature, voltage and charging rate at all times while the engine is running. The PMM
calculates the battery temperature by factoring in:
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The current intake manifold air temperature compared to the last temperature recorded when the ignition switch was turned OFF
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The current battery voltage compared to the last battery voltage recorded when the ignition switch was turned OFF
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The length of time since the last battery temperature calculation
If the battery temperature is below set limits, the PMM institutes steps to control the load.
The PMM calculates the voltage of the battery by making constant measurements and using the measurements to calculate the true battery voltage. If
the PMM detects a low voltage, the PMM institutes steps to control the load.
