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HOMESERVICE MANUALSCHEVROLET2006COBALT SS, 4D SEDAN, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 593 (DATA COMMUNICATION SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESSCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICETEST DESCRIPTION
2006 Chevrolet Cobalt SS, 4D Sedan, Standard

Test Description

2006 Chevrolet Cobalt SS, 4D Sedan, StandardSECTION Test Description
WARNING: This page is about a different car, the 2007 Pontiac G5 Pursuit, 2007 Pontiac G5, and 2007 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.

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

  1. 2:  A partial loss or intermittent loss of communication in the class 2 serial data circuit uses a different procedure than a total loss of communication of the class 2 serial data circuit.
  2. 10:  If there are no current DTCs that begin with the letter "U", the communication concern has been repaired.
  3. 11:  The communication concern may have prevented diagnosis of the customer complaint.
Scan Tool Does Not Communicate with Class 2 Device

Step Action Yes No
Schematic Reference: Data Communication Schematics 
Connector End View Reference: Master Electrical Component List
1 Does the scan tool power up? Go to Step 2  Go to Scan Tool Does Not Power Up 
2 
  1. Turn ON the ignition, with the engine OFF.
  2. Attempt to communicate with the powertrain control module (PCM) on the class 2 serial data circuit.
Does the scan tool communicate with PCM on the class 2 serial data circuit?		 Go to Testing for Intermittent Conditions and Poor Connections Go to Step 3 
3
  1. Turn the ignition OFF.
  2. Remove the scan tool from the data link connector (DLC).
  3. Remove the harness connector from the PCM that contains the class 2 serial data connector.
  4. Test for an open between the DLC terminal 2 and the terminal on the PCM harness connector that contains the class 2 serial data circuit.
Did you find and correct the condition?		 Go to Step 9  Go to Step 4 
4
IMPORTANT: Turn ON the ignition, with the engine OFF, when testing for a short to voltage. Use the DMM MIN/MAX function to capture intermittent conditions.
Test the class 2 serial data circuit for a short to ground or a short to voltage. Refer to Circuit Testing .Did you find and correct the condition?		 Go to Step 9  Go to Step 5 
5
  1. Turn OFF the ignition.
  2. Inspect for poor connections and terminal tension at the DLC. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 Go to Step 9  Go to Step 6 
6 Test the signal ground circuits of the DLC for an open or high resistance. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 Go to Step 9  Go to Step 7 
7 Inspect for poor connections and terminal tension at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 9  Go to Step 8 
8
IMPORTANT: Perform the module setup procedure if required. Refer to Control Module References .
Replace the suspect module. Refer to Control Module References for the appropriate Repair Instructions for module replacement.Did you complete the replacement?		 Go to Step 9  -
9
  1. Connect the PCM.
  2. Connect all the connectors.
  3. Install a scan tool.
  4. Turn ON the ignition leaving the engine OFF.
    5. IMPORTANT: The scan tool may require a power up reset before communication will occur due to a short on the class 2 serial data circuit. Turn OFF or disconnect the scan tool before you display DTCs.
  5. Wait for 10 seconds.
  6. Select the display DTCs function for the PCM. If using a Tech 2, use the Class 2 DTC Check feature in order to determine if the PCM has DTCs set.
  7. Record all of the displayed DTCs and the DTC status.
Did your record any DTCs which begin with a letter "U" and with a current status?		 Go to Step 11  Go to Step 10 
10  Did you record any DTCs which do not begin with a letter "U"? Go to Step 11  Go to Step 13 
11  Diagnose the DTCs as directed by the diagnostic procedures for the particular concern.
Did you complete the action?		 Go to Step 12  -
12 Did you diagnose all of the DTCs? Go to Step 13  Go to Step 11 
13 Clear the DTCs using the scan tool.
Did you complete the action?		 System OK -
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.