Computer/integrating Systems Chevrolet Equinox I

Computer/Integrating Systems Schematic Icons Icon Icon Definition CAUTION: When performing service on or near the SIR components or the SIR wiring, the SIR system must be disabled. Refer to SIR Disabling and Enabling Zones. Failure to observe the correct procedure could cause deployment of the SIR components, personal injury, or unnecessary SIR system repairs. IMPORTANT: Twisted-pair wires provide an effective shield that helps protect sensitive electronic components from electrical interference. In order to prevent electrical interference from degrading the performance of the connected components, you must maintain the proper specification when making any repairs to the twisted-pair wires shown : The wires must be twisted a minimum of 9 turns per 31 cm (12 in) as measured anywhere along the length of the wires. The outside diameter of the twisted wires must not exceed 6.0 mm (0.25 in)

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Body Control Module (BCM) C1

Body Control Module (BCM) C1 Connector Part Information OEM: 12084945 Service: 12084945 16-Way F Micro-Pack 100 Series (GY) Pin Wire Color Circuit No. Function A1 L-GN 1391 Driver Door Lock Relay Control A2 L-BU 195 Door Lock Relay Control A3 WH 194 Door Unlock Relay Control A4 PU/WH 5981 PRNDL A Signal A5 PK/BK 5982 PRNDL B Signal A6 OG/BK 5983 PRNDL C Signal A7 L-GN/WH 5984 PRNDL P Signal A8 YE 1836 Security System Sensor Signal B1 D-BU 1201 Headlamp Low Beam Signal B2 GY 731 Evaporator Temperature Sensor Signal B3 PU 719 Evaporator Temperature Sensor Low Reference B4 YE/BK 1138 DRL Ambient Light Sensor Low Reference B5 L-GN/BK 1137 DRL Ambient Light Sensor Signal B6 BN/WH 230 Instrument Panel Lamp Dimming Control B7 TN 470 Low Reference B8 OG/BK 1057 Low Reference

Body Control Module (BCM) C2

Body Control Module (BCM) C2 Connector Part Information OEM: 12110088 Service: See Catalog 24-Way F Micro-Pack 100 Series (GY) Pin Wire Color Circuit No. Function A1 PU 1807 Class 2 Serial Data A2 BN 96 Windshield Wiper Switch Pulse Delay Signal A3 D-BU 245 Passenger Door Lock Switch Unlock Supply Voltagel A4 BN/WH 1571 Traction Control Switch Signal A5 PK 94 Rear Window Wiper Switch Signal A6 OG 228 Windshield Washer Pump Control A7 PK 339 Ignition 1 Voltage A8 L-GN 80 Key In Ignition Switch Signal A9 - - Not Used A10 TN/BK 2500 High Speed GMLAN Serial Data (+) A11 TN 2501 High Speed GMLAN Serial Data (-) A12 D-GN 113 Windshield Wiper Switch Signal 2 B1-B2 - - Not Used B3 L-BU 74 Park Lamp Switch Signal B4 OG 192 Fog Lamp Switch Signal (T96) B5 TN/WH 746 Passenger Door Ajar Switch Signal B6 YE 43 Accessory Voltage B7 BN 9 Park Lamp Supply Voltage B8 BN 41 Ignition 3 Voltage B9 D-GN 392 Rear Window Washer Pump Control B10 TN/BK 2500 High Speed GMLAN Serial Data (+) B11 TN 2501 High Speed GMLAN Serial Data (-) B12 GY 112 Windshield Wiper Switch Signal 1

Body Control Module (BCM) C3

Body Control Module (BCM) C3 Connector Part Information OEM: 12110244 Service: 12110244 24-Way F Micro-Pack 100 Series (PK) Pin Wire Color Circuit No. Function A1 OG/WH 812 12-Volt Reference A2 WH 1080 Park Lamp Relay Control A3 TN 28 Horn Relay Control A4 TN/WH 816 A/T Shift Lock Solenoid Control A5 WH 352 Headlamp Relay Control A6 OG/BK 6848 Front Wiper Relay Control A7 - - Not Used A8 L-GN/BK 592 DRL Relay Control A9 YE 317 Fog Lamp Relay Control (T96) A10 YE 749 Security Indicator Control A11 YE 5420 Rear Wiper Relay Control A12 WH 193 Rear Defog Relay Control B1 WH 156 Dome Lamp Control B2-B3 - - Not Used B4 L-BU 244 Passenger Door Lock Switch Lock Supply Voltage B5 L-BU 1134 Park Brake Switch Signal B6 L-GN 66 A/C Request Signal B7 L-BU 292 Rear Defog Switch Signal B8 GY/BK 745 Left Front Door Ajar Switch Signal B9 PK 1200 Headlamp High Beam Signal B10 PU 333 Brake Fluid Level Switch Signal B11 - - Not Used B12 OG/BK 744 Liftgate Ajar Switch Signal

Body Control Module (BCM) C4

Body Control Module (BCM) C4 Connector Part Information OEM: 12110626 Service: 12110626 8-Way F Metri-Pack 280 Series, Flexlock (GY) Pin Wire Color Circuit No. Function A OG 1732 Courtesy Lamp Supply Voltage B-D - - Not Used E GY 8 I/P Lamps Dimmer Switch SIgnal F RD/WH 2540 Battery Positive Voltage G BK/WH 151 Ground H RD/WH 1640 Battery Positive Voltage

Data Link Connector (DLC)

Data Link Connector (DLC) Connector Part Information OEM: 348822-2 Service: 89046778 16-Way F Metri-Pack 150 Series (BK) Pin Wire Color Circuit No. Function 1 - - Not Used 2 PU 1807 Class 2 Serial Data 3 - - Not Used 4 BK 550 Ground 5 BK/WH 151 Ground 6 TN/BK 2500 High Speed GMLAN Serial Data (+) 7-13 - - Not Used 14 TN 2501 High Speed GMLAN Serial Data (-) 15 - - Not Used 16 RD/WH 340 Battery Positive Voltage

Splice Pack SP200

Splice Pack SP200 Connector Part Information OEM: 15305291 Service: 15305291 12-Way F M/P 280 Splice Saver SGL (BK) Pin Wire Color Circuit No. Function A-C PU 1807 Class 2 Serial Data D - - Class 2 Serial Data - Not Used E-G PU 1807 Class 2 Serial Data H-K - - Class 2 Serial Data - Not Used L PU 1807 Class 2 Serial Data (U2K) M PU 1807 Class 2 Serial Data (UE1)

DIAGNOSTIC CODE INDEX

DIAGNOSTIC CODE INDEX

Begin the system diagnosis with Diagnostic System Check - Vehicle in Vehicle DTC Information. The Diagnostic System Check - Vehicle will provide the following information

1. The identification of the control modules which are not communicating.
2. The identification of any stored diagnostic trouble codes (DTCs) and their status.

The use of the Diagnostic System Check - Vehicle will identify the correct procedures to begin vehicle diagnosis. These must be performed before system DTC or symptom diagnosis.

Scan Tool Data List

Scan Tool Data List

Circuit Description

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

DTC Descriptor

This diagnostic procedure supports the following DTC

DTC B1000 Electronic Control Unit (ECU) Performance

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.

DTC B1000

The body control module (BCM) stores the last 4 digits of the sensing and diagnostic module (SDM) part number, also called restraints ID. After the BCM is reprogrammed the restraints ID is set to zero. A restraints ID relearn is need to be performed for the BCM.

This diagnostic procedure supports the following DTC

DTC B1001 Option Configuration Error

Battery voltage is between 9-16 volts and data link communications operate normally.

The restraints ID stored in the BCM memory is zero.

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

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

This diagnostic procedure supports the following DTC

DTC B1004 Keep Alive Memory (KAM) Reset

The module microprocessor must be active/awake.

This DTC indicates the keep alive memory (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.

DTC B1004

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

This diagnostic procedure supports the following DTC

DTC B1009 EEPROM Checksum Mismatch

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.

DTC B1009

The body control module (BCM) is the power mode master responsible for sending the power mode message on the data buses. The BCM monitors Ignition 1 (Run/Crank), Ignition 2 (Acc/Run) and Ignition 3 (Run) signals from the ignition switch, and the engine run flag (ERF) in order to determine the present power mode. The following table represents correct BCM input signals corresponding to each ignition switch position.

Correct Ignition Switch Input Signals

DTC Descriptors

This diagnostic procedure supports the following DTCs

1. DTC B1372 Device Ignition 1 (Run/Crank) Circuit Low
2. DTC B1382 Device Ignition 2 (Acc/Run) Circuit Low

The only requirements are voltage and ground.

The following table describes the setting of the DTCs.

DTC B1372 or B1382

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 B1372 or B1382

The body control module (BCM) is the power mode master responsible for sending the power mode message on the data buses. The BCM monitors Ignition 1 (Run/Crank), Ignition 2 (Acc/Run) and Ignition 3 (Run) signals from the ignition switch, and the engine run flag (ERF) in order to determine the present power mode. The following table represents correct BCM input signals corresponding to each ignition switch position.

Correct Ignition Switch Input Signals

This diagnostic procedure supports the following DTCs

1. DTC B1377 Device Ignition 3 (ON) Circuit Low
2. DTC B1378 Device Ignition 3 (ON) Circuit High

The only requirements are voltage and ground.

The following table describes the setting of the DTCs.

DTC B1377 or B1378

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 B1377 or B1378

The powertrain control module (PCM) monitors its ignition 1 voltage circuit. The PCM compares the ignition 1 voltage with the body control module (BCM) Class 2 serial data power mode message. If the ignition 1 voltage signal is detected high while in Off Awake or RAP power modes the PCM will set DTC P2535. The DTC P2535 is a type C DTC. Refer to Diagnostic Trouble Code (DTC) Type Definitions in Engine Controls - 3.4L for more information about DTC types.

This diagnostic procedure supports the following DTC

DTC P2535 Ignition 1 Switch Circuit High Voltage

1. The vehicle is in PARK or NEUTRAL
2. The ignition switch is OFF

The ignition 1 voltage signal is higher than normal for more than 7 seconds.

The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.

A current DTC clears when the malfunction is no longer present.

DTC P2535

Modules connected to the GMLAN serial data circuit monitor for serial data communications on the GMLAN network during normal vehicle operation. Operating information and commands are exchanged among the modules. Each module on GMLAN network maintains a transmit error counter (TEC) and a receive error counter (REC). The counter values increase with detected errors and will decrease with error-free messages. If the TEC value exceeds 255 the controller removes itself from the network and a DTC U0001 will be set.

This diagnostic procedure supports the following DTC

DTC U0001 High Speed CAN Communication Bus

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to Symptoms - Vehicle in Vehicle DTC Information.

DTC U0001

Conditions for Running the DTCs

1. Voltage supplied to the module is in the normal operating voltage range.
2. The vehicle power mode requires serial data communication to occur.

A certain number of no valid transmitted messages on the GMLAN serial data circuits are detected by the module.

Action Taken When the DTCs Sets

1. The module suspends all message transmission.
2. The module uses default values for all parameters received on the GMLAN serial data circuits.
3. The module inhibits the setting of all other GMLAN communication 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. This DTC cannot be retrieved with a current status. Diagnosis of current DTC is accomplished via the symptom, Scan Tool Does Not Communicate with GMLAN Device. Refer to «Scan Tool Does Not Communicate with High Speed GMLAN Device»(/chevrolet/equinox/i-2004-2009/remont/communication-devices/#computerintegrating-systems__scan-tool-does-not-communicate-with) .
2. An intermittent condition is likely to be caused by a short on the GMLAN serial data circuits. Use the Scan Tool Does Not Communicate with GMLAN Device procedure in order to isolate an intermittent condition. Refer to «Scan Tool Does Not Communicate with High Speed GMLAN Device»(/chevrolet/equinox/i-2004-2009/remont/communication-devices/#computerintegrating-systems__scan-tool-does-not-communicate-with) .

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/equinox/i-2004-2009/remont/oem-general-information/#vehicle-dtc-information) prior to using this diagnostic procedure.
2. Review Strategy Based Diagnosis for an overview of the diagnostic approach.
3. Diagnostic Procedure Instructions provides an overview of each diagnostic category.

1. DTC U0073 00: High Speed Communication Bus
2. DTC U0073 71: Control Module Communication Bus Off Invalid
3. DTC U0073 72: Control Module Communication Bus Off Alive Counter Incorrect

Circuit/System Description

The high speed GMLAN serial data circuits are high speed serial data buses used to communicate information between the control modules. Typical data transmission speeds must be high enough to ensure that a required real-time response is maintained. The high speed GMLAN serial data circuits also connect directly to the data link connector (DLC).

1. Supply voltage to the modules are in the normal operating range.
2. The vehicle power mode requires serial data communications.

The module setting the DTC has attempted to establish communications on the GMLAN circuits more than 3 times.

1. The module suspends all message transmission.
2. The module uses default values for all parameters received on the serial data circuits.
3. The module inhibits the setting of all other communication 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 of 50 , without a repeat of the malfunction.

1. An intermittent condition is likely to be caused by a short on the high speed GMLAN serial data circuits.
2. This DTC cannot be retrieved with a current status. Diagnosis is accomplished using the symptom «Scan Tool Does Not Communicate with High Speed GMLAN Device»(/chevrolet/equinox/i-2004-2009/remont/communication-devices/#computerintegrating-systems__scan-tool-does-not-communicate-with) .
3. Refer to Data Link References for the specific modules using high speed GMLAN serial data.

Modules connected to the high speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. The supervision time-out period is 250 ms. Each message contains the identification number of the transmitter module.

This diagnostic procedure supports the following DTCs

1. DTC U0101 Lost Communication With Transmission Control Module (TCM)
2. DTC U0121 Lost Communication With Electronic Brake Control Module (EBCM)
3. DTC U0140 Lost Communication With Body Control Module (BCM)

1. Voltage supplied to the modules is in the normal operating voltage range.
2. The vehicle power mode requires serial data communication to occur.
3. The DTC U0001 does not have a current status.

A supervised periodic message that includes the transmitter module availability has not been received.

The module uses a default value for the missing parameter.

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. A poor connection at the inoperative module may cause this code to set.
2. An improperly powered module may cause this code to set.

DTC U0100-U0299

Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. When a module receives a message for a critical operating parameter, the module records the identification number of the module which sent the message for State of Health monitoring. A critical operating parameter is one which, when not received, requires that the module use a default value for that parameter. When a module does not associate an identification number with at least one critical parameter within 5 seconds of beginning serial data communication, DTC U1000 or U1255 is set. When more than one critical parameter does not have an identification number associated with it, the DTC will only be reported once.

The following modules communicate on the class 2 serial data circuit

1. The body control module (BCM)
2. The digital radio receiver (DRR)
3. The inflatable restraint sensing and diagnostic module (SDM)
4. The instrument panel cluster (IPC)
5. The power steering control module (PSCM)
6. The radio
7. The vehicle communication interface module (VCIM)

The BCM emulates the control modules that are on high speed GMLAN serial data circuits to the modules on class 2 serial data circuit. The BCM transmits multiple node alive messages using source IDs that correspond to each of the GMLAN nodes. This is in addition to the BCM behaving itself as a real node. The following module communicate on high speed GMLAN serial data circuits and are emulated by BCM on class 2 serial data circuit

1. The electronic brake control module (EBCM)
2. The engine control module (ECM)
3. The transmission control module (TCM)

This diagnostic procedure supports the following DTCs

DTC U1000 or U1255 Class 2 Data Link

1. Voltage supplied to the module is in the normal operating voltage range of 9-16 volts.
2. DTCs U1300, U1301 or U1305 do not have a current status.
3. The vehicle power mode requires serial data communication to occur.

A message containing a critical operating parameter has not been received within the last 5-10 seconds after establishing class 2 serial data communication.

The module uses a default value for the missing parameter.

When a malfunction such as an open fuse to a module occurs while modules are communicating, a DTC U1001-1254 Loss of XXX Communications is set current. When the modules stop communicating the current DTC U1001-1254 Loss of XXX Communications is cleared but the history DTC remains. When the modules begin to communicate again, the module with the open fuse will not be learned by the other modules so U1000 or U1255 is set current by the other modules. If the malfunction occurs when the modules are not communicating, only U1000 or U1255 is set.

Test Description

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

1. 2: A DTC U1001 - U1254 "Lost Communications with XXX" with a history status may indicate the cause of U1000 or U1255. A non communicating GMLAN module can cause the DTC setting, besides other DTC in the range of U2105-U2175.
2. 3: The modules not communicating are the likely cause of U1000 or U1255. The modules that are available on the class 2 serial data circuit are listed in the Circuit Description.
3. 8: The module which was not communicating due to a poor connection to the class 2 serial data circuit may have set DTC U1001 - U1254 "Lost Communications with XXX" for those modules that it was monitoring.
4. 10: The modules which can communicate indicate the module which cannot communicate. You must clear the serial data communication DTCs from these modules to avoid future misdiagnosis.
5. 12: If all modules are communicating, the module which set U1000 or U1255 may have done so due to some other condition.
6. 13: If all modules are communicating, the module which set U1000 or U1255 is the likely cause of the malfunction.

DTC U1000 and U1255

Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. When a module receives a message for a critical operating parameter, the module records the identification number of the module which sent the message for State of Health monitoring. A critical operating parameter is one which, when not received, requires that the module use a default value for that parameter. Once an identification number is learned by a module, it will monitor for that module's Node Alive message. Each module on the class 2 serial data circuit which is powered and performing functions that require detection of a communications malfunction is required to send a Node Alive message every 2 seconds. When no message is detected from a learned identification number for 5-10 seconds, a DTC U1xxx where xxx is equal to the 3-digit identification number is set.

The control module ID number list below provides a method for determining which module is not communicating. A module with a class 2 serial data circuit malfunction or which loses power during the current ignition cycle will have a Loss of Communication DTC set by other modules that depend on information from that failed module. The modules that can communicate will set a DTC indicating the module that can not communicate. The following modules communicate on class 2 serial data circuit

DTC U1001-U1254

The BCM emulates the control modules that are on high speed GMLAN serial data circuit to the modules on class 2 serial data circuit. The BCM transmits multiple Node Alive messages using source IDs that correspond to each of those high speed GMLAN nodes. This is in addition to the BCM behaving itself as a real node. The following module communicate on high speed GMLAN serial data circuit and are emulated by BCM on class 2 serial data circuit

DTC U1001-U1254

When more than one Loss of Communication DTC is set in either 1 module or in several modules, diagnose the DTCs in the following order

1. Current DTCs before history DTCs unless told otherwise in the diagnostic table.
2. The DTC which is reported the most times.
3. From the lowest number DTC to the highest number DTC.

1. The following diagnostic trouble codes do not have a current status: U1300 U1301 U1305
2. The vehicle power mode requires serial data communication to occur.

A node alive message has not been received from a module with a learned identification number within the last 5-10 seconds.

The module uses a default value for the missing parameter.

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. An intermittent open between the inoperative module and a star connector may cause these codes.
2. A poor connection at the inoperative module or a star connector may cause these codes.
3. An intermittent open in a star connector may cause these codes.
4. An improperly powered module may cause these codes.
5. An improperly communication on the high speed GMLAN serial data circuit may cause these codes.

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

1. 2: A module that does not communicate in high speed GMLAN link may cause the setting of the class 2 DTCs.
2. 3: A module which loses power during an ignition cycle will cause other modules to set lost communication DTCs.
3. 4: A module which loses power during an ignition cycle will cause other modules to set lost communication DTCs.
4. 5: The malfunction is due to an open in the class 2 serial data circuit or an open in the module.
5. 9: The module which was not communicating may have set lost communication DTCs for those modules that it was monitoring.
6. 11: The modules which can communicate indicate the module which cannot communicate. You must clear the DTC from these modules to avoid future misdiagnosis.

DTC U1001-U1254

Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. In addition to this, Node Alive messages are transmitted by each module on the class 2 serial data circuit about once every 2 seconds. When the module detects one of the following conditions on the class 2 serial data circuit for approximately 3 seconds, the setting of all other class 2 serial communication DTCs is inhibited and a DTC will set.

This diagnostic procedure supports the following DTCs

1. DTC U1300 Class 2 Data Link Low
2. DTC U1301 Class 2 Data Link High

1. Voltage supplied to the module is in the normal operating voltage range.
2. The vehicle power mode requires serial data communication to occur.

Conditions for Setting the DTCs

1. No valid messages are detected on the class 2 serial data circuit.
2. The voltage level detected on the class 2 serial data circuit is in one of the following conditions: High Low
3. The above conditions are met for approximately 3 seconds.

The module uses default values for all parameters received on the class 2 serial data circuit.

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. These DTCs cannot be retrieved with a current status. Diagnosis of current DTC is accomplished via the symptom, Scan Tool Does Not Communicate with a Class 2 Device. Refer to «Scan Tool Does Not Communicate with Class 2 Device»(/chevrolet/equinox/i-2004-2009/remont/communication-devices/#computerintegrating-systems) .
2. An intermittent condition is likely to be caused by a short on the class 2 serial data circuit. Use the Scan Tool Does Not Communicate with a Class 2 Device procedure in order to isolate an intermittent condition. Refer to «Scan Tool Does Not Communicate with Class 2 Device»(/chevrolet/equinox/i-2004-2009/remont/communication-devices/#computerintegrating-systems) .

Modules connected to the GMLAN serial data circuit monitor for serial data communications on the GMLAN network during normal vehicle operation. Operating information and commands are exchanged among the modules. The body control module (BCM) maintains a transmit error counter (TEC) and a receive error counter (REC). The counter values increase with detected errors and will decrease with error-free messages. If the TEC value exceeds 255 the BCM removes itself from the high speed GMLAN network and a DTC U2100 will be set.

This diagnostic procedure supports the following DTC

DTC U2100 High Speed CAN Communication Bus

1. Voltage supplied to the module is in the normal operating voltage range.
2. The vehicle power mode requires serial data communication to occur.

A certain number of no valid transmitted messages on the GMLAN serial data circuits are detected by the module. The engine will not start when there is a total malfunction of the high speed GMLAN serial data circuits while the engine is not running. The following conditions may cause a total loss of high speed GMLAN data communication

1. A short between high speed GMLAN (+) and high speed GMLAN (-) circuits
2. Any of the high speed GMLAN serial data circuits shorted to ground or voltage
3. A module internal malfunction that causes a short to voltage or ground on the high speed GMLAN circuits
4. Any of the high speed GMLAN serial data circuits open

1. The module suspends all message transmission.
2. The module uses default values for all parameters received on the high speed GMLAN serial data circuits.
3. The module inhibits the setting of all other high speed GMLAN communication 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.

The BCM can set this DTC as current because it is the gateway between the class 2 and high speed GMLAN serial data circuits, and the BCM diagnostics is performed on class 2 data link. Refer to Data Link Communications Description and Operation for more information about data link communication.

The high speed GMLAN serial data bus uses two 120 ohms terminating resistors that are in parallel with the high speed GMLAN (+) and (-) circuits. One of the resistors is connected at the BCM and the other is at the engine control module (ECM). When testing for a short between high speed GMLAN (+) and (-) a reading of 60 ohms is normal. If the high speed GMLAN serial data is open testing the resistance between high speed GMLAN (+) and (-) will read about 120 ohms.

DTC U2100

Modules connected to the GMLAN serial data circuit monitor for serial data communications on the GMLAN network during normal vehicle operation. Operating information and commands are exchanged among the modules. Each module on GMLAN network maintains a transmit error counter (TEC) and a receive error counter (REC). The counter values increase with detected errors and will decrease with error-free messages. If the TEC value exceeds 255 the controller removes itself from the network and a DTC U2100 will be set.

This diagnostic procedure supports the following DTC

DTC U2104 Controller Area Network (CAN) Bus Reset Counter Overrun

1. Voltage supplied to the module is in the normal operating voltage range.
2. The vehicle power mode requires serial data communication to occur.

A certain number of no valid transmitted messages on the GMLAN serial data circuits are detected by the module. The engine will not start when there is a total malfunction of the high speed GMLAN serial data circuits while the engine is not running. The following conditions may cause a total loss of high speed GMLAN data communication

1. A short between high speed GMLAN (+) and high speed GMLAN (-) circuits
2. Any of the high speed GMLAN serial data circuits shorted to ground or voltage
3. A module internal malfunction that causes a short to voltage or ground on the high speed GMLAN circuits
4. Any of the high speed GMLAN serial data circuits open

1. The module suspends all message transmission.
2. The module uses default values for all parameters received on the high speed GMLAN serial data circuits.
3. The module inhibits the setting of all other high speed GMLAN communication 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. This DTC cannot be retrieved with a current status. Diagnosis of current DTC is accomplished via the symptom, Scan Tool Does Not Communicate with high speed GMLAN Device. Refer to «Scan Tool Does Not Communicate with High Speed GMLAN Device»(/chevrolet/equinox/i-2004-2009/remont/communication-devices/#computerintegrating-systems__scan-tool-does-not-communicate-with) .
2. An intermittent condition is likely to be caused by a short on the high speed high speed GMLAN serial data circuits. Use the Scan Tool Does Not Communicate with high speed GMLAN Device procedure in order to isolate an intermittent condition. Refer to «Scan Tool Does Not Communicate with High Speed GMLAN Device»(/chevrolet/equinox/i-2004-2009/remont/communication-devices/#computerintegrating-systems__scan-tool-does-not-communicate-with) .

Modules connected to the high speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. The supervision time-out period is 250 ms. Each message contains the identification number of the transmitter module.

This diagnostic procedure supports the following DTCs

1. DTC U2105 Lost Communication With Engine Control Module (ECM)
2. DTC U2106 Lost Communication With Transmission Control Module (TCM)
3. DTC U2107 Lost Communication With Body Control Module (BCM)
4. DTC U2108 Lost Communication With Electronic Brake Control Module (EBCM)

1. Voltage supplied to the modules is in the normal operating voltage range.
2. The vehicle power mode requires serial data communication to occur.
3. The DTC U2100 does not have a current status.

A supervised periodic message that includes the transmitter module availability has not been received.

The module uses a default value for the missing parameter.

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. A poor connection at the inoperative module may cause this code to set.
2. An improperly powered module may cause this code to set.

DTC U2105-U2199

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/equinox/i-2004-2009/remont/oem-general-information/#vehicle-dtc-information) in Vehicle DTC Information before using the symptom tables in order to verify that all of the following are true: There are no DTCs set. The control modules can communicate via the serial data links.
2. Review the system operation in order to familiarize yourself with the system functions. Refer to: «Data Link Communications Description and Operation»(/chevrolet/equinox/i-2004-2009/remont/communication-devices/#computerintegrating-systems) «Body Control System Description and Operation»(/chevrolet/equinox/i-2004-2009/remont/communication-devices/#computerintegrating-systems) «Retained Accessory Power (RAP) Description and Operation»(/chevrolet/equinox/i-2004-2009/remont/communication-devices/#computerintegrating-systems)

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the systems. Refer to «Checking Aftermarket Accessories»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__checking-aftermarket-accessories) in Wiring Systems.
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 Conditions and Poor Connections in Wiring Systems.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. «Scan Tool Does Not Power Up»(/chevrolet/equinox/i-2004-2009/remont/communication-devices/#computerintegrating-systems)
2. «Scan Tool Does Not Communicate with Class 2 Device»(/chevrolet/equinox/i-2004-2009/remont/communication-devices/#computerintegrating-systems)
3. «Scan Tool Does Not Communicate with High Speed GMLAN Device»(/chevrolet/equinox/i-2004-2009/remont/communication-devices/#computerintegrating-systems__scan-tool-does-not-communicate-with)
4. «Power Mode Mismatch»(/chevrolet/equinox/i-2004-2009/remont/communication-devices/#computerintegrating-systems)
5. «Retained Accessory Power (RAP) On After Timeout»(/chevrolet/equinox/i-2004-2009/remont/communication-devices/#computerintegrating-systems__retained-accessory-power-rap-on-after)
6. «Retained Accessory Power (RAP) Inoperative»(/chevrolet/equinox/i-2004-2009/remont/communication-devices/#computerintegrating-systems__retained-accessory-power-rap-inoperative)

The data link connector (DLC) is a standardized 16 cavity connector. Connector design and location is dictated by an industry wide standard, and is required to provide the following

1. Scan tool power battery positive voltage at terminal 16
2. Scan tool power ground at terminal 4
3. Common signal ground at terminal 5

The scan tool will power up with the ignition OFF. Some modules however, will not communicate unless the ignition is ON and the power mode master (PMM) module sends the appropriate power mode message.

The number below refers to the step number on the diagnostic table.

1. 4: If the battery positive voltage and ground circuits of the DLC are functioning properly, the malfunction must be due to the scan tool.

Scan Tool Does Not Power Up

Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. Connecting a scan tool to the data link connector (DLC) allows communication with the modules for diagnostic purposes.

The following conditions will cause a total loss of class 2 serial data communication

1. A class 2 serial data circuit shorted to ground.
2. A class 2 serial data circuit shorted to voltage.
3. An internal condition within a module or connector on the class 2 serial data circuit, that causes a short to voltage or ground to the class 2 serial data circuit.

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

1. 2: A partial malfunction in the class 2 serial data circuit uses a different procedure from a total malfunction of the class 2 serial data circuit. The following modules communicate on the class 2 serial data circuit: Body control module (BCM) Digital radio receiver (DRR) Inflatable restraint sensing and diagnostic module (SDM) Instrument panel cluster (IPC) Power steering control module (PSCM) Radio Vehicle communication interface module (VCIM)
2. 3: The following DTCs may be retrieved with a history status, but are not the cause of the present condition. U1300 U1301 U1305
3. 6: A state of health DTC with a history status may be present along with a U1000 or U1255 code having a current status. This indicates that the malfunction occurred when the ignition was ON.
4. 7: Data link connector terminals 2 and 5 provide the connection to the class 2 serial data circuit and the signal ground circuit respectively.
5. 10: A poor connection at DLC terminal of the splice pack - SP200 would cause this condition but will not set a DTC.
6. 11: An open in the class 2 serial data circuit between the DLC and splice pack - SP200 will prevent the scan tool from communicating with any module. This condition will not set a DTC.
7. 12: The class 2 serial data circuit is shorted to voltage or ground. The condition may be due to the wiring or due to a malfunction in one of the modules. When testing the wire for a short, make sure there is not a module connected to the wire being tested. This test isolates the BCM class 2 serial data circuit.
8. 14: The BCM detects that the ignition is ON and sends the appropriate power mode message to the other modules. Therefore, the BCM must remain connected to the DLC for any other module to communicate with the scan tool. This test isolates the splice pack - SP200 serial data circuits.

Scan Tool Does Not Communicate with Class 2 Device

Scan Tool Does Not Communicate with High Speed GMLAN Device

Modules connected to the high speed GMLAN serial data circuits monitor for serial data communications on the high speed GMLAN network during normal vehicle operation. Operating information and commands are exchanged among the modules. When a module detects a bus-off condition a DTC U0001, U2100 or U2104 will be set. Generally these DTCs can be retrieved as history only, with the exception of body control module (BCM) that can set DTC U2100 as current, because it communicates with the scan tool on class 2.

The high speed GMLAN serial data bus uses two 120 ohms terminating resistors that are in parallel with the high speed GMLAN (+) and (-) circuits. One of the resistors is connected at the body control module (BCM) and the other is at the engine control module (ECM). If testing for a short between high speed GMLAN (+) and (-) a reading of 60 ohms is normal. If the high speed GMLAN serial data is open testing the resistance between high speed GMLAN (+) and (-) will read about 120 ohms.

The engine will not start when there is a total malfunction of the high speed GMLAN serial data circuits while the engine is not running. The following conditions may cause a total loss of high speed GMLAN data communication

1. A short between high speed GMLAN (+) and high speed GMLAN (-) circuits
2. Any of the high speed GMLAN serial data circuits shorted to ground or voltage
3. A module internal malfunction that causes a short to voltage or ground on the high speed GMLAN circuits
4. Any of the high speed GMLAN serial data circuits open

Scan Tool Does Not Communicate with High Speed GMLAN Device

The body control module (BCM) is the power mode master responsible for sending the power mode message on the data buses. The BCM monitors Ignition 1 (Run/Crank), Ignition 2 (Acc/Run) and Ignition 3 (Run) signals from the ignition switch, and the engine run flag (ERF) in order to determine the present power mode. Refer to Body Control System Description and Operation for the applicable power mode look up table.

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.

Power Mode Mismatch

Retained Accessory Power (RAP) On After Timeout

Retained Accessory Power (RAP) On After Timeout

Retained Accessory Power (RAP) Inoperative

Retained Accessory Power (RAP) Inoperative

Control Module References

Control Module References

Data Link References

This table identifies which serial data link that a particular module uses for in-vehicle data transmission. Some modules may use more than one data link to communicate. Some modules may have multiple communication circuits passing through them without actively communicating on that data link. This table is used to assist in correcting a communication malfunction. For the description and operation of these serial data communication circuits, refer to Data Link Communications Description and Operation .

Data Link References

Removal Procedure

1. Rotate the ignition switch to the OFF position.
2. Remove the radio bezel. Refer to «Radio Replacement»(/chevrolet/equinox/i-2004-2009/remont/entertainment-systems/#entertainment-systems) in Entertainment.
3. Disconnect the body control module (BCM) electrical harnesses.
4. Remove the BCM from the instrument panel (I/P) retainer: Pry the BCM tabs from the locking tabs on the underside of the restraint. Slide the BCM out of the retainer.

Installation Procedure

1. Install the BCM.
2. Install the radio bezel. Refer to «Radio Replacement»(/chevrolet/equinox/i-2004-2009/remont/entertainment-systems/#entertainment-systems) in Entertainment.
3. Slide the BCM tabs into the slots in the I/P retainer until the tabs lock into place.
4. Connect the electrical connectors.
5. Program a new or a remanufactured BCM. Refer to «Body Control Module (BCM) Programming/RPO Configuration»(/chevrolet/equinox/i-2004-2009/remont/communication-devices/#computerintegrating-systems__body-control-module-bcm-programmingrpo-configuration) .

1. Disable the SIR system. Refer to «SIR Disabling and Enabling Zone 8»(/chevrolet/equinox/i-2004-2009/remont/airbag/#supplemental-inflatable-restraint-system) .
2. Remove the console assembly. Refer to «Console Replacement»(/chevrolet/equinox/i-2004-2009/remont/gauges-instrument-panels/#instrument-panel-gages-and-console) in Instrument Panel, Gages, and Console.
3. Remove the retainers from the connector position assurance (CPA) and disconnect the electrical connectors.
4. Remove the nuts and remove the SDM.

1. Remove any dirt, grease, or other contaminants from the mounting surface.
2. Install the SDM to the vehicle with the nuts. Tighten: Tighten the nuts to 10 N.m (89 lb in).
3. Install the console assembly. Refer to «Console Replacement»(/chevrolet/equinox/i-2004-2009/remont/gauges-instrument-panels/#instrument-panel-gages-and-console) in Instrument Panel, Gages, and Console.
4. Enable the SIR system. Refer to «SIR Disabling and Enabling Zone 8»(/chevrolet/equinox/i-2004-2009/remont/airbag/#supplemental-inflatable-restraint-system) .
5. Reprogram the BCM. Refer to «Body Control Module (BCM) Programming/RPO Configuration»(/chevrolet/equinox/i-2004-2009/remont/communication-devices/#computerintegrating-systems__body-control-module-bcm-programmingrpo-configuration) .

Body Control Module (BCM) Programming/RPO Configuration

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.

1. Programming the BCM.
2. Programming Theft Deterrent System Components.
3. Program Key Fobs

Programming the BCM

Pass-Thru programming allows the scan tool to remain connected to the terminal and to the vehicle throughout the programming process. The vehicle must be in close proximity to the terminal while using Pass-Thru. Refer to Service Programming System (SPS) in Programming and Setup for more information.

Programming Theft Deterrent System Components

Perform the Programming Theft Deterrent System Components in Theft Deterrent after successfully finishing the Setup New BCM procedure. If the Programming Theft Deterrent System Components in the Theft Deterrent procedure is not performed after a BCM replacement, one of the following conditions will occur

1. The vehicle will not be protected against theft by the PASSLOCK system.
2. The engine will not crank or start.

Program Key Fobs

Refer to Transmitter Programming in Keyless Entry for the proper procedure.

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.

The communication among modules is performed through the class 2 serial data circuit and high speed GMLAN serial data circuit. The modules that need real time communication are attached to the high speed GMLAN network. The body control module (BCM) is the gateway between the networks. The purpose of the gateway is to transfer information from one network to another. The gateway will interact with each network according to that network's transmission model. Refer to Body Control System Description and Operation for more information about the gateway.

GMLAN Circuit Description

The data link connector (DLC) allows a scan tool to communicate with the high speed GMLAN serial data circuit. The serial data is transmitted on two twisted wires that allow speed up to 500 Kbps. The twisted pair is terminated with two 120 ohms resistors, one is internal to the ECM and the other is internal to the BCM. The resistors are used to reduce noise on the high speed GMLAN bus during normal vehicle operation. The high speed GMLAN is a differential bus. The high speed GMLAN serial data bus (+) and high speed GMLAN serial data (-) are driven to opposite extremes from a rest or idle level. The idle level which is approximately 2.5 volts is considered a recessive transmitted data and is interpreted as a logic 1. Driving the lines to their extremes adds 1 volt to high speed GMLAN serial data bus (+) and subtracts 1 volt from high speed GMLAN serial data bus (-) wire. This dominant state is interpreted as a logic 0. GMLAN network management supports selective start up and is based on virtual networks. A virtual network is a collection of signals started in response to a vehicle event. The starting of a virtual network signifies that a particular aspect of the vehicles's functionality has been requested. A virtual network is supported by virtual devices which represents a collection of signals owned by a single physical device. So, any physical device can have one or more virtual devices. The signal supervision is the process of determining whether an expected signal is being received or not. Failsofting is the ability to substitute a signal with a default value or a default algorithm, in the absence of a valid signal. Some messages are also interpreted as a "heartbeat" of a virtual device. If such a signal is lost, the application will set a no communication code against the respective virtual device. This code is mapped on the Tech 2 screen as a code against the physical device. Note that a loss of serial data DTC does not normally represent a failure of the module that set it.

The interaction between high speed GMLAN and class 2 is assured by BCM, which is the gateway. Any message from the class 2 modules to the high speed GMLAN modules is translated by BCM without carrying the original transmitter ID. Therefore the GMLAN modules consider the BCM as being the originator of all class 2 messages that they receive.

Class 2 Circuit Description

The data link connector (DLC) allows a scan tool to communicate with the class 2 serial data circuit. Class 2 serial data is transmitted on a single wire at an average of 10.4 Kbps. The bus is active at 7.0 volts nominal and inactive at ground potential. Each module communicating on the class 2 serial data line sends a state of health (SOH) message every 2 seconds to ensure that the module is operating properly. When a module stops communicating on the class 2 serial data line, for example if the module loses power or ground, the SOH message it normally sends on the data line every 2 seconds disappears. Other modules on the class 2 serial data line, which expect to receive that SOH message, detect its absence; those modules in turn set an internal DTC associated with the loss of SOH of the non-communicating module. The DTC is unique to the module which is not communicating, for example, when the body control module (BCM) SOH message disappears, several modules set DTC U1064. Note that a loss of serial data DTC does not normally represent a failure of the module that set it.

The BCM emulates the GMLAN modules on the class 2, embedding the original transmitter ID in GMLAN messages to class 2. Therefore the class 2 modules can set specific non communications DTCs against GMLAN modules.

The data link connector (DLC) is a standardized 16 cavity connector. Connector design and location is dictated by an industry wide standard, and is required to provide the following

1. Scan tool power battery positive voltage at terminal 16
2. Scan tool power ground at terminal 4
3. Common signal ground at terminal 5
4. Class 2 signal at terminal 2
5. High speed GMLAN serial data bus (+) at terminal 6
6. High speed GMLAN serial data bus (-) at terminal 14

GMLAN Serial Data Line

The GMLAN serial data communications circuit on this vehicle is in a linear topology. The following modules are connected to the link, in order from DLC to the end of the linear configuration

1. The body control module (BCM)
2. The vehicle communication interface module (VCIM)
3. The electronic brake control module (EBCM)
4. The transmission control module (TCM)
5. The engine control module (ECM)

VCIM communicates functionally and physically on class 2 only. The high speed GMLAN circuits just pass through the module.

Class 2 Serial Data Line

The class 2 serial data communications circuit on this vehicle is in a star configuration. The star has one splice pack, located nearby the DLC.

The following modules communicate on the class 2 serial data circuit

1. The body control module (BCM)
2. The digital radio receiver (DRR)
3. The instrument panel cluster (IPC)
4. The inflatable restraint sensing and diagnostic module (SDM)
5. The power steering control module (PSCM)
6. The radio
7. The vehicle communication interface module (VCIM)

BCM Overview

The main features of the body control module (BCM) are

1. The BCM is the gateway between class 2 serial data circuit and high speed GMLAN serial data circuit.
2. The BCM controls multiple functions.
3. The BCM is the power mode master.

Gateway

The body control module (BCM) communicates functionally on both class 2 and high speed GMLAN serial data buses. The BCM is the gateway between the buses and transfers serial data messages from one subnet to another. Physical communication of the BCM with the scan tool is through class 2 serial data circuit.

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 inputs can be

1. Sensors and switches that are directly connected to the BCM
2. Class 2 serial data messages received from other vehicle systems connected to the class 2 serial data link
3. GMLAN serial data messages received from other vehicles systems connected to the high speed GMLAN 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 or high speed GMLAN serial data link. The system capable of performing the required function will respond to the BCM messages.

Some of the other system functions that BCM controls or contributes to are

1. Audible warnings-Refer to «Audible Warnings Description and Operation»(/chevrolet/equinox/i-2004-2009/remont/gauges-instrument-panels/#instrument-panel-gages-and-console__audible-warnings-description-and-operation) in Instrument Panel, Gages, and Console.
2. Exterior lighting control-Refer to «Exterior Lighting Systems Description and Operation»(/chevrolet/equinox/i-2004-2009/remont/exterior-lights/#lighting-systems) in Lighting Systems.
3. Interior lighting-Refer to «Interior Lighting Systems Description and Operation»(/chevrolet/equinox/i-2004-2009/remont/exterior-lights/#lighting-systems) in Lighting Systems.
4. Automatic door locks-Refer to «Power Door Locks Description and Operation»(/chevrolet/equinox/i-2004-2009/remont/door-locks-anti-theft-systems/#door-system-mirror-system-window-system) in Doors.
5. Keyless entry-Refer to «Keyless Entry System Description and Operation»(/chevrolet/equinox/i-2004-2009/remont/door-locks-anti-theft-systems/#keyless-entry-system) in Keyless Entry.
6. Theft deterrent-Refer to «Content Theft Deterrent (CTD) Description and Operation»(/chevrolet/equinox/i-2004-2009/remont/door-locks-anti-theft-systems/#theft-deterrent-system__content-theft-deterrent-ctd-description-and) in Theft Deterrent.
7. Wipers/washers-Refer to «Wiper/Washer System Description and Operation»(/chevrolet/equinox/i-2004-2009/remont/wiperwasher-systems/#wiper-system-washer-system__wiperwasher-system-description-and-operation) in Wipers/Washer Systems.
8. Rear defogger-Refer to «Rear Window Defogger Description and Operation»(/chevrolet/equinox/i-2004-2009/remont/heated-glassdefoggers/#stationary-windows) in Stationary Windows.
9. Horn-Refer to «Horns System Description and Operation»(/chevrolet/equinox/i-2004-2009/remont/horns/#horn-system) in Horns.

Power Mode

The BCM is the power mode master (PMM). Refer to Power Mode Description and Operation for more information.

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 monitors Ignition 1 (Run/Crank), Ignition 2 (Acc/Run), and Ignition 3 (Run) signals from the ignition switch, and the engine run flag (ERF) message from the engine control module (ECM) in order to determine the present power mode.

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

Correct Ignition Switch Inputs

The power mode message is a periodic with event message type and is transmitted by the PMM at every 2 seconds on class 2 link and at every 250 ms on high speed GMLAN link. The power modes are identical transmitted on both class 2 and high speed GMLAN serial data circuits with the exception of retained accessory power (RAP). RAP is transmitted only on class 2 and it is mapped on high speed GMLAN as Off Awake.

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 body control module (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 powertrain control module (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.

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 or liftgate is opened or until the RAP function timer reaches its shut-off limit.

The class 2 RAP power mode is mapped to GMLAN serial data circuit as Off Awake power mode. Refer to Data Link Communications Description and Operation for more information on data link communications. The BCM monitors the ignition switch signals, battery condition and the doors status to determine whether RAP should be initiated. The modules that support the RAP power mode will operate the systems under their control as required by their RAP power mode strategy.

RAP will end when one of the following conditions is met

1. The BCM detects the opening of a passenger compartment door.
2. The RAP timer expires.
3. The battery capacity decreases below a prescribed limit.
4. Any other ignition switch state is chosen.

The function supported in the RAP power mode is the operation of the radio.

See also:
• Diagnostic System Check - Vehicle
• Circuit Testing
• Wiring Repairs
• Testing for Intermittent Conditions and Poor Connections
• Connector Repairs
• Ignition Switch Replacement
• Diagnostic Trouble Code (DTC) Type Definitions
• Power Distribution Schematics
• Master Electrical Component List
• DTC U0107
• Diagnostic Trouble Code (DTC) List - Vehicle
• Checking Aftermarket Accessories
• Symptoms - Lighting Systems
• Symptoms - Body Rear End
• DTC Symptom Description
• Radio/Audio System Schematics (U1C)
• Body Control Module Programming and Setup
• OnStar Schematics
• Communication Interface Module (OnStar) Programming and Setup
• ABS Schematics
• Driver Seat Schematics
• HVAC Schematics
• Re-Calibrating Actuators
• SIR Schematics
• Inflatable Restraint Sensing and Diagnostic Module Programming and Setup
• Inside Rearview Mirror Schematics
• Instrument Cluster Schematics
• Service Programming System (SPS)
• Power Steering System Schematics
• Power Steering Control Module Programming and Setup
• Radio Setup
• Power Sunroof Schematics
• Automatic Transmission Controls Schematics
• Transmission Control Module Programming and Setup
• Fastener Notice
• Programming Theft Deterrent System Components
• Transmitter Programming
• Audible Warnings Description and Operation
• Power Door Locks Description and Operation
• Keyless Entry System Description and Operation
• Content Theft Deterrent (CTD) Description and Operation
• Wiper/Washer System Description and Operation
• Horns System Description and Operation
• DTC B1000
• Control Module References
• Body Control Module (BCM) Programming/RPO Configuration
• Scan Tool Does Not Communicate with High Speed GMLAN Device
• Retained Accessory Power (RAP) On After Timeout
• Retained Accessory Power (RAP) Inoperative