Data Communication System: Overview Chevrolet Malibu VI facelift

Data Communication Schematic Icons

Data Communication 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 . 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 Connector Parts Information

Body Control Module (BCM) - C1 Connector Terminal Identification

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Body Control Module (BCM) - C2 Connector Parts Information

Body Control Module (BCM) - C2 Connector Terminal Identification

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Body Control Module (BCM) - C3 Connector Parts Information

Body Control Module (BCM) - C3 Connector Terminal Identification

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Body Control Module (BCM) - C4 Connector Parts Information

Body Control Module (BCM) - C4 Connector Terminal Identification

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Data Link Connector (DLC) Connector Parts Information

Data Link Connector (DLC) Connector Terminal Identification

Test Description

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

1. 3: If body control module (BCM) will not power up the vehicle cannot establish the correct power mode. This step tests for the correct power supply conditions for the BCM.
2. 4: If DTC U2103 is set as history and you can communicate with the suspect module, the malfunction is an intermittent communication buss, power supply, ground or internal module malfunction.
3. 5: This step tests for the correct power supply conditions of the suspect module or modules.
4. 6: This step identifies which of the GMLAN busses the module or modules use for communication. Use the «Data Link References»(ref-269123-S34565663282007102900000) for identifying the correct buss to analyze.
5. 11: The module which was not communicating due to an open in the GMLAN serial data circuits may have set Loss of Communication DTCs for those modules that it was monitoring.
6. 20: The modules which can communicate indicate the module which cannot communicate. You must clear the DTC from these modules to avoid future misdiagnosis.

DTC U2103

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

1. 3: If the body control module (BCM) will not power up the vehicle cannot establish the correct power mode. This step tests for the correct power supply conditions for the BCM.
2. 4: If DTC U2105 to U2177 are set as history and you can communicate with the suspect module, the malfunction is an intermittent communication buss, power supply, ground or internal module connection.
3. 5: This step tests for the correct power supply conditions of the suspect module or modules.
4. 7: The powertrain control module (PCM) that is used in the 3.5L (LX9) powertrain package can lose communication with the buss if there is a malfunction in the camshaft position (CMP) or the crankshaft position (CKP) sensors 12-volt reference circuit.
5. 8: This step identifies which of the GMLAN busses the module or modules use for communication. Use the «Data Link References»(ref-269123-S34565663282007102900000) for identifying the correct buss to analyze.
6. 13: The module which was not communicating due to an open in the GMLAN serial data circuits may have set Loss of Communication DTCs for those modules that it was monitoring.
7. 14: The modules which can communicate indicate the module which cannot communicate. You must clear the DTC from these modules to avoid future misdiagnosis.

DTC U2105-U2199

Symptoms - Computer/Integrating Systems

1. Perform the «Diagnostic System Check - Vehicle»(ref-269144-S34864310592007102900000) 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»(ref-269123-S11989525502007102900000) «Body Control System Description and Operation»(ref-269123-S27006402142007102900000)

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

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

1. 2: A partial malfunction in the high speed GMLAN serial data circuits uses a different procedure from a total malfunction of the high speed GMLAN data circuits. Refer to «Data Link References»(ref-269123-S34565663282007102900000) to identify which modules communicate on the high speed GMLAN serial data circuits.
2. 3: The DTC U2100 may be retrieved with a history status, but is not the cause of the present condition.
3. 8: Data link connector terminals 6 and 14 provide the connection to the GMLAN serial data high circuit and the GMLAN serial data low circuit respectively.
4. 17: The communication malfunction may have prevented diagnosis of the customer complaint.

Scan Tool Does Not Communicate with High Speed GMLAN Device

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

1. 2: A partial malfunction in the low speed GMLAN serial data circuits uses a different procedure from a total malfunction of the low speed GMLAN data circuits. Refer to «Data Link References»(ref-269123-S34565663282007102900000) to identify which modules communicate on the low speed GMLAN serial data circuits.
2. 3: The DTC U2100 may be retrieved with a history status, but is not the cause of the present condition.
3. 7: Data link connector terminal 1 provides the connection to the GMLAN serial data low circuit and the GMLAN serial data low circuit respectively.
4. 16: The communication malfunction may have prevented diagnosis of the customer complaint.

Scan Tool Does Not Communicate with Low Speed GMLAN Device

Body Control System Description and Operation

This vehicle's body control module (BCM) has a bussed electrical center integrated into the housing. Body control relays and fuses are installed directly on the BCM, which simplifies wiring and junction blocks on the vehicle. The body control system consists of the BCM and its associated controls. Battery positive voltage is provided to the BCM from IBCM BATT 1 fuse and the IBCM BATT 2 fuse in the underhood fuse block. The module grounds are wired to ground G201, G203 and G305. The BCM is wired to the GMLAN High speed serial data buss, and the GMLAN Low speed serial data buss, as well as discrete input and output terminals to control the functions of the vehicle's body.