GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2000 🢒 Grand Prix 🢒 Body and Accessories 🢒 Data Link Communications 🢒 Scan Tool Does Not Communicate with Class 2 Data Line

Diagnostic Aids

The class 2 serial data circuit may have an intermittent open, short to voltage or short to ground. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Step

Action

Value(s)

Yes

No

1

Does the scan tool power up?

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Go to Step 2

Go to Scan Tool Does Not Power Up

2
  1. Turn ON the ignition leaving the engine OFF.
  2. Attempt to communicate with each module on the class 2 serial data circuit.

Does the scan tool communicate with any module on the Class 2 serial data circuit?

--

Go to Step  3

Go to Step 4

3

Did the scan tool communicate with all the modules on the class 2 serial data circuit from the previous step?

--

Go to Diagnostic Aids

Go to Step 7

4
  1. Turn OFF the ignition.
  2. Disconnect the scan tool from the data link connector (DLC).
  3. Inspect for poor connections at the DLC terminals 2 and 5. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Control Module References for the applicable Diagnostic System Check

Go to Step 5

5

Test the DLC ground circuit terminal 5 for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Control Module References for the applicable Diagnostic System Check

Go to Step 6

6
  1. Disconnect all the modules on the class 2 serial data circuit.
  2. Test the class 2 serial data circuit for a short to ground or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Control Module References for the applicable Diagnostic System Check

Go to Step 8

7

Test the battery positive voltage circuit of the module that is not communicating for an open or a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Control Module References for the applicable Diagnostic System Check

Go to Step 8

8
  1. Turn OFF the ignition.
  2. Test the ground circuit of the module that is not communicating for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Control Module References for the applicable Diagnostic System Check

Go to Step 9

9

Test the class 2 serial data circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 10

10

Inspect for poor connections at the class 2 serial data circuit of the module that is not communicating. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 11

11

Replace the module which is not communicating. Refer to Control Module References for the appropriate repair instructions.

Did you complete the replacement?

--

Go to Step 12

--

12
  1. Reconnect all of the disconnected modules and any disconnected connectors.
  2. Install a scan tool.
  3. Turn ON the ignition leaving the engine OFF.
  4. Wait for 10 seconds. 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 prior to performing this test.
  5. Try to communicate with all of the modules on the class 2 serial data circuit.

Does the scan tool communicate with all the modules on the class 2 serial data circuit?

--

Go to Step 13

Go to Step 2

13
  1. Select the Display DTCs function for each module. (If using a Tech 2, use the Class 2 DTC Check feature in order to determine which modules do have DTCs set).
  2. Record all of the displayed DTCs and the DTC status.

Did you record any DTCs which begin with a "U" and with a current status?

--

Go to Step 15

Go to Step 14

14

Did you record any DTCs which do not begin with a "U"?

--

Go to Step 15

Go to Step 17

15

Diagnose the DTCs as directed by the diagnostic procedures for the particular module or malfunction. Refer to Control Module References for the applicable Diagnostic System Check.

Did you complete the action?

--

Go to Step 16

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16

Did you diagnose all of the DTCs?

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Go to Step 17

Go to Step 15

17

Use the scan tool in order to clear the DTCs.

Did you complete the action?

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System OK

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