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Retained Accessory Power System Chevrolet Impala VIII

Accessories Control Systems 7 illustrations ~1635 words

SCHEMATIC & ROUTING DIAGRAMS

Note. For wiring schematics, refer to SYSTEM WIRING DIAGRAMS (IMPALA) or SYSTEM WIRING DIAGRAMS (MONTE CARLO) .

Diagnostic Starting Point - Retained Accessory Power

Begin the system diagnosis with a Diagnostic System Check - Retained Accessory Power .

The use of the Diagnostic System Check will identify the correct procedure for diagnosing the system and where the procedure is located.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. 2) - Lack of communication may be due to a partial malfunction of the class 2 serial data circuit or due to a total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.
  2. 4) - The presence of DTCs which begin with U indicate some other module is not communicating. The specified procedure will compile all the available information before tests are performed.

Scheme 47

Scheme 47: Scan Tool Output Controls
Scheme 47: Scan Tool Output Controls

Scheme 48

Scheme 48: Scan Tool Data List
Scheme 48: Scan Tool Data List

Scan Tool Data Definitions

Software Part Number: Part number of component program or the ECU. Used to determine applicability to vehicle RPO content.

Accessory Switch: Input from ignition switch Accessory circuit. Used to determine power mode. Hot in ACCESSORY and RUN.

Driver Door Open Sw.: Input from the driver door indicating door status (Open-Closed).

Door Ajar Switches: Input showing state of the passenger door(s).

Doors Battery Fd: Indicates completion of the power circuit for the door control functions.

Doors System Gnd: Indicates the completion state of the ground circuit for the door functions.

Electronics Battery Fd: Data indicates the voltage detected by the control module on the power circuit for the module internal devices.

Electronics Battery Fd: Input indicates the completion state of the power circuit for the module internal devices.

Electronics System Gnd: Indicates the completion state of the ground circuit for the module internal devices.

Ignition 0: Input to the control module from the ignition switch indicating the Ignition 0 position. Switch closed (HOT) in ignition switch positions Unlock, Accessory, Run, Crank.

Ignition 1: Input to the control module from the ignition switch indicating the Ignition 1 position. Switch closed (HOT) in ignition switch positions Run, Crank.

Inadvertent Power Output: Input indicating the sensed state of the inadvertent power request circuit.

Inadvertent Power Relay: Output indicating the state as commanded by the control module.

Lamp Request: Input telling the control module to initiate inadvertent power management.

Load Management Status: Output indicating the power mode commanded.

Loads Battery Fd: Indicates the completion state of the supply circuit for the high current loads.

Loads System Gnd: Indicates completion state of the ground circuit for the high current loads.

Pass Door Jamb Sw.: Input showing the state of the front passenger door.

RAP Relay: Output indicates state that the control module has commanded.

Scheme 49

Scheme 49: Diagnostic Trouble Code (DTC) List
Scheme 49: Diagnostic Trouble Code (DTC) List

Circuit Description

The BCM interfaces with the vehicle's power distribution system through the RAP relay. The RAP relay allows the BCM to control the application of power to the feed circuits to the sunroof and the power windows. When the ignition switch is in either the ACC or the RUN position, the BCM energizes the RAP relay by applying battery voltage to the RAP relay control circuit.

The BCM turns off the RAP relay when the ignition switch is in the START position. The RAP feature therefore disables during engine cranking.

When the ignition switch turns from ON or ACC to LOCK or OFF, with all of the vehicle doors closed, the BCM leaves the RAP relay energized for 10 minutes, or until any vehicle door opens and the BCM detects a ground signal in one of the door ajar circuits.

Conditions for Setting the DTC

  1. The BCM detects no voltage at the RAP relay control circuit when the BCM is trying to energize the RAP relay.
  2. The above condition must be present for more than 300 milliseconds.

Action Taken When the DTC Sets

  1. The BCM stores DTC B1477 in memory.
  2. The RAP relay powered functions will not operate.
  3. The circuits powered by the RAP relay will never be powered if the relay control circuit is open.

Conditions for Clearing the DTC

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

The numbers below refer to the step numbers on the diagnostic table.

  1. 2) - Listen for an audible click when the RAP relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
  2. 3) - Verifies that the BCM is providing voltage to RAP relay.
  3. 4) - Tests for an open in the ground circuit to the RAP relay.
  4. 5) - Tests if voltage is constantly being applied to the RAP relay.

The BCM interfaces with the vehicle's power distribution system through the RAP relay. The RAP relay allows the BCM to control the application of power to the feed circuits to the sunroof and the power windows. When the ignition switch is in either the ACC or the RUN position, the BCM energizes the RAP relay by applying battery voltage to control circuit.

The BCM turns off the RAP relay when the ignition switch is in the START position. The RAP feature therefore disables during engine cranking.

When the ignition switch turns from ON or ACC to LOCK or OFF, with all of the vehicle doors closed, the BCM leaves the RAP relay energized for 10 minutes, or until any vehicle door opens and the BCM detects a ground signal in one of the door ajar circuits.

Conditions for Running the DTC

The BCM must be commanding the RAP relay to energize.

  1. The BCM detects a short to battery in the RAP relay control circuit when the BCM is trying to de-energize the RAP relay.
  2. The condition above must be present for more than 300 milliseconds.
  1. The circuits powered by the RAP relay remain powered at all times if the RAP relay control circuit is shorted to battery voltage.
  2. The BCM stores DTC B1478 in memory.
  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

The numbers below refer to the step numbers on the diagnostic table.

  1. 2) - Listen for an audible click when the RAP relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
  2. 3) - Tests for voltage at the coil side of the RAP Relay.
  3. 4) - This step verifies that the body control module (BCM) is providing ground to the RAP relay.
  4. 5) - This step tests if ground is constantly being applied to the RAP relay.

Scheme 50

Scheme 50
Scheme 50

Scheme 51

Scheme 51
Scheme 51

Symptoms - Retained Accessory Power

Important: Review the system operation in order to familiarize yourself with the system functions. Refer to Retained Accessory Power (RAP) Description and Operation. See Retained Accessory Power (Rap) Description & Operation .

Visual/Physical Inspection

  1. Inspect for aftermarket devices which may affect the operation of the retained accessory power system. Refer to «CHECKING AFTERMARKET ACCESSORIES»(/chevrolet/impala/viii-1999-2006/remont/accessories-control-systems/#wiring-systems-general-information__checking-aftermarket-accessories) .
  2. Inspect the easily accessible or visible system components for obvious damage or conditions which may cause the symptom.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to TESTING FOR INTERMITTENT & POOR CONNECTIONS .

Symptom List

see scheme 8and see scheme 9.

Scheme 52

Scheme 52: Symptom List
Scheme 52: Symptom List

Scheme 53

Scheme 53
Scheme 53

Serial Data Control of Retained Accessory Power RAP)

Retained accessory power (RAP) is a vehicle power mode that permits the operation of selected customer convenience items after the ignition switch is turned OFF. These selected items will remain in operation until a passenger compartment door is opened or until the RAP function timer reaches its shut-off limit.

The modules listed below all receive a RAP message from the body control module (BCM) over the serial data circuits. The BCM monitors the ignition switch position, battery condition and passenger compartment door status to determine whether RAP should be initiated. The BCM then sends a message to the listed modules telling them that they are in RAP power mode. The modules then support the operation of the systems under their control as required by their RAP power mode strategy.

RAP will end when one of the following conditions are met

  1. The BCM receives an input (as a hard wired input from the door switches) indicating the opening of a passenger compartment door.
  2. The BCM receives a message from its internal timer indicating the end of the RAP period after 10 minutes.
  3. The BCM detects a decrease in battery capacity below a prescribed limit.
  4. The transition from OFF to RUN/ON or ACC of the ignition switch.

The BCM then sends a serial data message to the listed devices ending the RAP function.

The devices receiving serial data messages for RAP functions are

  1. Auxiliary Power Drop Connector
  2. Driver Information Center (DIC)
  3. Instrument Panel Cluster (IPC)
  4. Radio
  5. Remote CD player (if equipped)
  6. Vehicle Interface Unit (VIU) (if equipped).

Relay Control of Retained Accessory Power (RAP)

Retained accessory power (RAP) is a vehicle power mode that permits the operation of selected customer convenience items after the ignition switch is turned OFF. These selected items will remain in operation until a passenger compartment door is opened or until the RAP function timer reaches its shut-off limit.

The BCM closes the RAP relay in either the RAP function as described above or if the BCM detects a RUN/ON or accessory power mode. This provides power for the following

  1. The power windows
  2. The sunroof control module (if equipped)

The BCM opens the RAP relay to end the RAP function when it ends the RAP function as outlined in the previous text.

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