Body Control System Chevrolet Chevy Express H2500

Fastener Tightening Specifications

Fastener Tightening Specifications

Schematic and Routing Diagrams

For Chevy Express, see

1. G1500: «BODY CONTROL MODULES»(ref-154376-S33446997372003080900000)
2. G2500: «BODY CONTROL MODULES»(ref-154377-S04509626612003080900000)
3. G3500: «BODY CONTROL MODULES»(ref-154378-S29199591132003080900000)
4. H1500: «BODY CONTROL MODULES»(ref-154379-S06971294512003080900000)
5. H2500: «BODY CONTROL MODULES»(ref-154380-S27042461452003080900000)

For Cutaway 3500, see BODY CONTROL MODULES .

For RV Cutaway 3500, see BODY CONTROL MODULES .

For GMC Savana, see

1. G1500: «BODY CONTROL MODULES»(ref-154351-S24635336482003080900000)
2. G2500: «BODY CONTROL MODULES»(ref-154352-S41757763122003080900000)
3. G3500: «BODY CONTROL MODULES»(ref-154353-S30997533682003080900000)
4. H1500: «BODY CONTROL MODULES»(ref-154354-S01209000342003080900000)
5. H2500: «BODY CONTROL MODULES»(ref-154355-S16804352642003080900000)

For Savana Camper Special 3500, see BODY CONTROL MODULES .

For Savana Special 3500, see BODY CONTROL MODULES .

Scheme 1

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Scheme 10

Begin the diagnosis of the body control system by performing the diagnostic system check for the system in which the customer concern is apparent.

The diagnostic system check will direct you to the correct procedure for diagnosing the system and where the procedure is located.

Scan Tool Output Controls

Scan Tool Output Controls

Scheme 11

Scan Tool Data Definitions

Accessory Switch: Input from ignition switch accessory circuit. Used to determine power mode. Hot in ACC and ON.

Battery Voltage: The scan tool displays 0.0-16.0 volts. The battery voltage input represents the system voltage measured at the BCM ignition feed input.

Ignition Unlock: Input to the control module from the ignition switch indicating the Ignition 0 position. Switch closed (HOT) in ignition switch positions UNLOCK, ACC, ON, and START

Key in Ignition: Input from ignition switch indicating that the ignition key is inserted into the ignition switch. HOT with key in ignition switch.

Module Part Number: Indicates the module part number.

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

Software Design Suffix: Details the software version used.

Software Part Number: Part number of the software.

Diagnostic Trouble Code (DTC) List

Diagnostic Trouble Code (DTC) List

Circuit Description

The internal fault detection is handled inside the control module. No external circuits are involved.

Conditions for Running the DTC

The module runs the program to detect an internal fault when power up is commanded. The only requirements are voltage and ground. This program runs even if the voltage is out of the valid operating range.

Conditions for Setting the DTC

The module has detected an internal malfunction.

Action Taken When the DTC Sets

The module refuses all additional inputs.

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.

Diagnostic Aids

1. This DTC may be stored as a history DTC without affecting the operation of the module. If stored only as a history DTC and not retrieved as a current DTC, do not replace the module.
2. If this DTC is retrieved as both a current and history DTC, replace the module.

Scheme 12

After enter RUN mode, the inflatable restraint sensing and diagnostic module (SDM) receives the VIN from BCM, via class 2 serial data circuit. SDM receives also a message from BCM containing its restraints ID. The restraints ID contains the last four digits of the SDM part number. The module compares the information stored in its memory with the information received from the BCM.

Battery voltage is between 9-16 volts.

The restraints ID that is stored in the SDM does not match the restraints ID that is stored in the BCM or the VIN information that is stored in the SDM does not match the VIN information that is stored in the BCM.

The following module specific actions may occur

1. The SDM commands the AIR BAG indicator ON via class 2 serial data circuit.
2. The SDM disables all deployment loops.

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.

DTC B1001 is an indication that the restraints ID or the VIN stored in both the BCM and SDM do not match. If any of the modules mentioned above were replaced, the replaced module need to be reprogrammed for proper operation.

Scheme 13

The internal fault detection is handled inside the control module. No external circuits are involved.

The module microprocessor must be active/awake.

This DTC indicates the KAM in the module has been reset. It is a normal occurrence when battery positive voltage or ground is removed from the module, such as a battery disconnect.

The microprocessor reverts back to the base programmed critical operating data until new data is learned and stored in KAM.

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.

1. This DTC may be stored as a history DTC without affecting the operation of the module. If stored only as a history DTC and not retrieved as, a current DTC, do not replace the module.
2. If this DTC is retrieved as both a current and history DTC, replace the module.

Scheme 14

As part of normal data processing, the module performs a data programming check on its writes to the electrically erasable read only memory (EEPROM). The EEPROM write error detection is handled inside the control module. No external circuits are involved.

The module runs the program to detect an EEPROM write error. The only requirements are battery positive voltage and ground. This program runs even if the battery positive voltage is out of the valid operating range.

The module writes information to a data block in the EEPROM. The module then reads the data and compares it to what was sent to the data block. If the data does not match after 3 consecutive attempts, the module sets the DTC.

The module writes to another area of the EEPROM, this becomes the new permanent area to store the data. The data location is allowed to change until all of the available EEPROM is used. If a B1004 DTC is also set, the module reverts to base operation values programmed for those blocks of data that have failed. The blocks of data that have not failed the checksum test are not affected.

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.

1. This DTC may be stored as a history DTC without affecting the operation of the module. If stored only as a history DTC and not retrieved as a current DTC, do not replace the module.
2. If this DTC is retrieved as both a current and history DTC, replace the module.

Scheme 15

The electrically erasable programmable read-only memory (EEPROM) check sum error detection is handled inside the control module. No external circuits are involved.

The module runs the program to detect an EEPROM checksum error after each wake-up. The only requirements are battery positive voltage and ground. This program runs even if the voltage is out of the valid operating range.

The module retains an inverse copy of the digital value stored in certain blocks of memory in the EEPROM. The module then reads the information from those certain blocks and adds the stored inverse value to the current value. If they do not equal 0, the module sets the DTC.

The module reverts to base operation values programed for those blocks of data that have failed the check sum test. The blocks of data that have not failed the check sum test are not affected.

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.

1. This DTC may be stored as a history DTC without affecting the operation of the module. If stored only as a history DTC and not retrieved as a current DTC, do not replace the module.
2. If this DTC is retrieved as both a current and history DTC, replace the module.

Scheme 16

The BCM monitors the battery voltage through the battery positive voltage circuit.

1. For Chevy Express G1500, refer to «BODY CONTROL MODULES»(ref-154376-S33446997372003080900000) .
2. For Chevy Express G2500, refer to «BODY CONTROL MODULES»(ref-154377-S04509626612003080900000) .
3. For Chevy Express G3500, refer to «BODY CONTROL MODULES»(ref-154378-S29199591132003080900000) .
4. For Chevy Express H1500, refer to «BODY CONTROL MODULES»(ref-154379-S06971294512003080900000) .
5. For Chevy Express H2500, refer to «BODY CONTROL MODULES»(ref-154380-S27042461452003080900000) .
6. For Cutaway G3500, refer to «BODY CONTROL MODULES»(ref-154383-S32308619062003080900000) .
7. For RV Cutaway G3500, refer to «BODY CONTROL MODULES»(ref-154387-S16280956632003080900000) .
8. For Savana G1500, refer to «BODY CONTROL MODULES»(ref-154351-S24635336482003080900000) .
9. For Savana G2500, refer to «BODY CONTROL MODULES»(ref-154352-S41757763122003080900000) .
10. For Savana G3500, refer to «BODY CONTROL MODULES»(ref-154353-S30997533682003080900000) .
11. For Savana H1500, refer to «BODY CONTROL MODULES»(ref-154354-S01209000342003080900000) .
12. For Savana H2500, refer to «BODY CONTROL MODULES»(ref-154355-S16804352642003080900000) .
13. For Savana Camper Special G3500, refer to «BODY CONTROL MODULES»(ref-154356-S42114502422003080900000) .
14. For Savana Special G3500, refer to «BODY CONTROL MODULES»(ref-154357-S17909509172003080900000) .

The voltage supplied to the body control module is in the range of 7-26 volts.

The BCM senses a battery voltage below or above the specified range of 9-16 volts.

The above condition lasts for at least 1 second.

1. The BCM will disable all its outputs when a high voltage condition is detected.
2. The setting of this DTC inhibits the setting of other DTCs.

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.

1. The following may cause an intermittent: A damaged terminal A backed out terminal A poor terminal tension A chafed wire A broken wire inside the insulation
2. When diagnosing for an intermittent short or an open, manipulate the wire harness while watching the test equipment for changes.

Scheme 17

The body control module (BCM) is the power mode master responsible for sending ignition switch position information on the class 2 serial data link. The BCM monitors 3 discrete wires from the ignition switch contacts and the engine run flag (ERF) in order to determine the present power mode. The BCM communicates this power mode information to all class 2 modules on the class 2 serial data link. The following table represents correct BCM power mode data

Scheme 18

The only requirements are voltage and ground.

One of the 3 monitored ignition switch circuits has malfunctioned. The DTC will set, if one of the following situations is present

Scheme 19

The BCM implements default actions for each ignition switch position when faults are detected.

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.

Scheme 20

Scheme 21

The internal fault detection is handled inside the control module. No external circuits are involved.

The microprocessor runs the program to detect an internal fault when power up is commanded. The only requirements are voltage and ground. This program runs even if the voltage is out of the valid operating range.

1. The control module detects an internal write malfunction.
2. The control module detects an internal checksum malfunction.

If equipped, the following module specific actions may occur

1. The ABS indicator turns on.
2. The BRAKE Warning indicator turns on.
3. The SERVICE 4WD indicator turns on and the system will be disabled.
4. The Service 4 Wheel Steering indicator turns on and the system will be disabled.
5. The SERVICE RIDE SYS or SERVICE RIDE CONTROL message is displayed.
6. The SERVICE SUSPENSION SYS message is displayed.
7. The TCS indicator turns on.

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.

1. This DTC may be stored as a history DTC without affecting the operation of the module. If stored only as a history DTC and not retrieved as a current DTC, do not replace the module.
2. If this DTC is retrieved as both a current and history DTC, replace the module.

Scheme 22

Important: Review the system operation in order to familiarize yourself with the system functions. Refer to Body Control System Description and Operation .

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the body control system. Refer to «CHECKING AFTERMARKET ACCESSORIES»(/chevrolet/chevy-express-h2500/2003-2003/remont/electrical-component-locations/#wiring-systems-general-information__checking-aftermarket-accessories) .
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Intermittent

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

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom: Power Mode Mismatch .

Normal vehicle class 2 communications and module operations will not begin until the system power mode has been identified. Discrete wires from the ignition switch contacts are monitored by the power mode master (PMM) module in order to determine the correct power mode. The PMM communicates the system power mode to all class 2 modules on the class 2 serial data line. Refer to Body Control System Description and Operation to identify which module is the PMM and the applicable power mode look up table.

Test Description

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

1. 6. This step tests for battery voltage on the signal circuits that are not required.
2. 7. This step tests for no battery voltage on the required signal circuits.
3. 8. If any ignition switch parameters that should be inactive in the present ignition switch position are active, 2 ignition switch signal circuits may be shorted together.
4. 9. This step eliminates open circuits as the cause of the malfunction.

Scheme 23

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Scheme 28

1. Remove the right side knee bolster trim panel. Refer to «KNEE BOLSTER REPLACEMENT - RIGHT»(/chevrolet/chevy-express-h2500/2003-2003/remont/gauges-instrument-panels/#instrument-panel-gages-and-console__knee-bolster-replacement-right) .
2. Disconnect the electrical connectors (2) from the Body Control Module (BCM) (1).
3. Release the tabs (2) retaining the BCM (1) to the bracket.
4. Remove the BCM (1) from the vehicle.

Scheme 29

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Scheme 31

1. Install the BCM (1) into the bracket. Ensure the BCM (1) is engaged in the bracket, under the retaining tabs (2).
2. Connect the electrical connectors (2) to the BCM (1).
3. Install the right side knee bolster trim panel. Refer to «KNEE BOLSTER REPLACEMENT - RIGHT»(/chevrolet/chevy-express-h2500/2003-2003/remont/gauges-instrument-panels/#instrument-panel-gages-and-console__knee-bolster-replacement-right) .
4. If the BCM has been replaced the module will need to be programed. Program the BCM. Refer to «Body Control Module (BCM) Programming/RPO Configuration»(/chevrolet/chevy-express-h2500/2003-2003/remont/body-cab-control-systems/#body-control-system) .

Introduction

The procedures below are designed to set-up the body control module (BCM) correctly during BCM related service. Before you start, read these procedures carefully and completely.

Important: The following procedures must be followed

1. Read this procedure carefully and completely.
2. The BCM will not function properly if the Setup New BCM procedure is not performed.
3. Perform the «PROGRAMMING THEFT DETERRENT SYSTEM COMPONENTS»(/chevrolet/chevy-express-h2500/2003-2003/remont/door-locks-anti-theft-systems/#theft-deterrent-system) after successfully finishing the Setup New BCM procedure. If the «PROGRAMMING THEFT DETERRENT SYSTEM COMPONENTS»(/chevrolet/chevy-express-h2500/2003-2003/remont/door-locks-anti-theft-systems/#theft-deterrent-system) procedure is not performed after a BCM replacement, one of the following conditions will occur: The vehicle will not be protected against theft by the PASSLOCK system. The engine will not crank nor start.

Setup New Body Control Module (BCM)

Important: After the procedure is completed, the personalization settings of the BCM are set to a default setting. Inform the customer that the personalization must be set again.

For 4.3L, refer to REMOTE PROGRAMMING or PASS-THRU PROGRAMMING or OFF-BOARD PROGRAMMING or OFF-BOARD PASS-THRU PROGRAMMING .

For 4.8L, 5.3L or 6.0L, refer to REMOTE PROGRAMMING or PASS-THRU PROGRAMMING or OFF-BOARD REMOTE PROGRAMMING or OFF-BOARD PASS-THRU PROGRAMMING .

Important: After programming, perform the following to avoid future misdiagnosis

1. Turn the ignition OFF for 10 seconds.
2. Connect the scan tool to the data link connector.
3. Turn the ignition ON with the engine OFF.
4. Use the scan tool in order to retrieve history DTCs from all modules.
5. Clear all history DTCs.

BCM Functions

The Body Control Module (BCM) performs multiple body control functions. The BCM can control devices directly connected to its outputs based on input information. The BCM evaluates this information and controls certain body control systems by commanding outputs on or off. The BCM control inputs can be

1. Sensors and switches that are directly connected to the BCM
2. Class 2 serial data received from other control modules connected to the class 2 serial data link.

The BCM is also capable of controlling other vehicle systems that are not directly wired to the BCM.

The BCM does this by sending specific messages on the class 2 serial data link. The control module capable of performing the required function will respond to the BCM message.

The BCM controls these functions

1. Audible warnings, refer to «AUDIBLE WARNINGS DESCRIPTION AND OPERATION»(/chevrolet/chevy-express-h2500/2003-2003/remont/gauges-instrument-panels/#instrument-panel-gages-and-console__audible-warnings-description-and-operation) .
2. Automatic door locks, refer to «POWER DOOR LOCKS DESCRIPTION AND OPERATION»(/chevrolet/chevy-express-h2500/2003-2003/remont/door-locks-anti-theft-systems/#door-system-mirror-system-window-system) .
3. Automatic headlamp control, refer to «EXTERIOR LIGHTING SYSTEMS DESCRIPTION AND OPERATION»(/chevrolet/chevy-express-h2500/2003-2003/remont/exterior-lights/#lighting-systems) .
4. Interior lighting, refer to «INTERIOR LIGHTING SYSTEMS DESCRIPTION AND OPERATION»(/chevrolet/chevy-express-h2500/2003-2003/remont/exterior-lights/#lighting-systems) .
5. Keyless entry (AUO option), refer to «KEYLESS ENTRY SYSTEM DESCRIPTION AND OPERATION»(/chevrolet/chevy-express-h2500/2003-2003/remont/door-locks-anti-theft-systems/#keyless-entry-system) .
6. Passlock theft deterrent, refer to «VEHICLE THEFT DETERRENT (VTD) DESCRIPTION AND OPERATION»(/chevrolet/chevy-express-h2500/2003-2003/remont/door-locks-anti-theft-systems/#theft-deterrent-system) .
7. Retained Accessory Power (RAP), refer to «RETAINED ACCESSORY POWER (RAP) DESCRIPTION AND OPERATION»(/chevrolet/chevy-express-h2500/2003-2003/remont/accessories-control-systems/#retained-accessory-power-system) .

Serial Data Power Mode

On vehicles that have several control modules connected by serial data circuits, one module is the power mode master (PMM). On this vehicle the PMM is the Body Control Module (BCM). The BCM uses 3 signals from the ignition switch. These are the Ignition 0 (Unlock), Ignition 1 (Run/Crank), and Accessory.

To determine the correct power mode the BCM uses

1. The state of these signals
2. The sequence of switch closures received by the BCM
3. The status of the engine run flag

The chart indicates the power modes detected and transmitted by the BCM

Scheme 32

Fail-safe Operation

Since the operation of the vehicle systems depends on the power mode, there is a fail-safe plan in place should the BCM fail to send a power mode message. The fail-safe plan covers modules with discrete ignition signal inputs as well as those modules using exclusively serial data control of power mode.

Serial Data Messages

The modules that depend exclusively on serial data messages for power modes stay in the state dictated by the last valid BCM message until they receive the engine status from the PCM. If the BCM fails, the modules monitor the serial data circuit for the engine run flag serial data. If the engine run flag serial data is true, indicating that the engine is running, the modules fail-safe to "Run".

In this state the modules and their subsystems can support all operator requirements. If the engine run flag serial data is false, indicating that the engine is not running, the modules fail-safe to "OFF-AWAKE". In this state the modules are constantly checking for a change status message on the serial data circuits and can respond to both local inputs and serial data inputs from other modules on the vehicle.

Discrete Ignition Signals

Those modules that have discrete ignition signal inputs also remain in the state dictated by the last valid BCM message received on the serial data circuits. They then check the state of their discrete ignition input to determine the current valid state. If the discrete ignition input is active, B+, the modules will fail-safe to the "RUN" power mode. If the discrete ignition input is not active, open or 0 voltage, the modules will fail-safe to "OFF-AWAKE". In this state the modules are constantly checking for a change status message on the serial data circuits and can respond to both local inputs and serial data inputs from other modules on the vehicle.

See also:
• CHECKING AFTERMARKET ACCESSORIES
• TESTING FOR INTERMITTENT AND POOR CONNECTIONS
• KNEE BOLSTER REPLACEMENT - RIGHT
• PROGRAMMING THEFT DETERRENT SYSTEM COMPONENTS
• REMOTE PROGRAMMING
• PASS-THRU PROGRAMMING
• OFF-BOARD PROGRAMMING
• OFF-BOARD PASS-THRU PROGRAMMING
• REMOTE PROGRAMMING
• PASS-THRU PROGRAMMING
• OFF-BOARD REMOTE PROGRAMMING
• OFF-BOARD PASS-THRU PROGRAMMING
• AUDIBLE WARNINGS DESCRIPTION AND OPERATION
• POWER DOOR LOCKS DESCRIPTION AND OPERATION
• EXTERIOR LIGHTING SYSTEMS DESCRIPTION AND OPERATION
• KEYLESS ENTRY SYSTEM DESCRIPTION AND OPERATION
• RETAINED ACCESSORY POWER (RAP) DESCRIPTION AND OPERATION
• DTC B1000