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Data Link Communications System: Diagnosis Pontiac Vibe I

Communication Devices ~838 words

Diagnostic Starting Point - Data Link Communications

Begin the diagnosis of the data link communications 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 within the Data Link Communications section when a communication malfunction is present.

Symptoms - Data Link Communications

Important: Review the Scan Tool operation in order to familiarize yourself with the system functions. Refer to the scan tool user manual.

Visual/Physical Inspection

Inspect the DLC connector for obvious damage or conditions which could cause the symptom.

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»(ref-186704-S38611323192005083100000)
  2. «SCAN TOOL DOES NOT COMMUNICATE WITH VCM/PCM»(ref-186704-S27672706902005083100000)
  3. «SCAN TOOL DOES NOT COMMUNICATE WITH EBCM»(ref-186704-S25250918422005083100000)
  4. «SCAN TOOL DOES NOT COMMUNICATE WITH SDM»(ref-186704-S08471159492005083100000)

Circuit Description

The data link connector (DLC) provides operating power for the scan tool at terminal 16 (battery positive voltage) and at terminal 4 (ground). The DLC provides the class 2 serial data signals at terminal 7. The scan tool will power up with the ignition OFF. Many modules, however, will not communicate unless the DIM detects that the ignition is ON and sends the appropriate power mode message.

The provision for communicating with the powertrain control module (PCM) is the data link connector (DLC). The DLC is located under the instrument panel (IP). The DLC is used to link a scan tool to the PCM serial data stream. Some common uses of the scan tool are listed below

  1. Identifying the stored diagnostic trouble codes (DTCs)
  2. Reading the serial data stream
  3. Clearing the DTCs
  4. Storing the Freeze Frame data

Diagnostic Aids

Some scan tools may require an external power supply. Ensure the scan tool is correctly connected to the power feed.

Ensure that the correct application (model year, carline, VIN code) has been selected on the scan tool. If communications are still not established, try the scan tool on another vehicle in order to ensure that the scan tool or the connecting cables are not the cause of the malfunction. Always try the scan tool on a vehicle that uses the same DLC terminal for serial data communication.

An intermittent malfunction may be caused by a fault in the Heated Oxygen Sensor (HO2S) circuit. Inspect the wiring harness and components for an intermittent condition. Refer to INTERMITTENT CONDITIONS in Engine Controls.

The provision for communicating with the brake pressure modulator valve (BPMV) is the data link connector (DLC). The DLC is located under the instrument panel. The DLC is used to link a scan tool to the BPMV serial data stream. Some common uses of the scan tool are listed below

  1. Identifying the stored diagnostic trouble codes (DTCs)
  2. Reading the serial data stream
  3. Clearing the DTCs
  4. Storing the Freeze Frame data

Some scan tools may require an external power supply. Make sure your scan tool is using the correct power feed.

Ensure that the correct application (model year, carline, VIN code) has been selected on the scan tool. If communications are still not established, try the scan tool on another vehicle in order to ensure that the scan tool or the connecting cables are not the cause of the malfunction. Always try the scan tool on a vehicle that uses the same DLC terminal for serial data communication.

Any circuitry that is suspect to an intermittent complaint should be thoroughly inspected for the following

  1. Backed-out terminals
  2. Improper mating of terminals
  3. Broken electrical connector locks
  4. Improperly formed or damaged terminals
  5. Faulty terminal-to-wiring connections
  6. Physical damage to the wiring harness
  7. A broken conductor inside the wire insulation
  8. Corrosion of the electrical connections, the splices, or the terminals

The provision for communicating with the inflatable restraint sensing and diagnostic control (SDM) is the data link connector (DLC). The DLC is located under the instrument panel. The DLC is used to link a scan tool to the SDM serial data stream. Some common uses of the scan tool are listed below

  1. Identifying the stored diagnostic trouble codes (DTCs)
  2. Reading the serial data stream
  3. Clearing the DTCs
  4. Storing the Freeze Frame data

Some scan tools may require an external power supply. Make sure your scan tool is using the correct power feed.

Ensure that the correct application (model year, carline, VIN code) has been selected on the scan tool. If communications are still not established, try the scan tool on another vehicle in order to ensure that the scan tool or the connecting cables are not the cause of the malfunction. Always try the scan tool on a vehicle that uses the same DLC terminal for serial data communication.

Any circuitry that is suspect to an intermittent complaint should be thoroughly inspected for the following

  1. Backed-out terminals
  2. Improper mating of terminals
  3. Broken electrical connector locks
  4. Improperly formed or damaged terminals
  5. Faulty terminal-to-wiring connections
  6. Physical damage to the wiring harness
  7. A broken conductor inside the wire insulation
  8. Corrosion of the electrical connections, the splices, or the terminals

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