For 1990-2009 cars

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Establish communication with the same system on a different vehicle. Did you establish communication? | -- | Go to Step 2 | Go to Step 3
2 |

1. Turn the ignition switch off.
2. Inspect for a proper connection of the scan tool to the data link connector (DLC).

Is the scan tool properly connected?

--

Go to Step 4

Go to Step 5

3 | Refer to scan tool diagnosis. Is the scan tool malfunctioning? | -- | System OK | --
4 |

1. Turn the ignition switch on.
2. Establish communication with the modules that are connected to the serial data line.

Did you establish communication?

--

Go to Step 6

Go to Step 7

5 |

1. Repair the connector.
2. Reconnect the scan tool.

Did you establish communication?

--

System OK

--

6 |

1. Turn the ignition switch off.
2. Disconnect the module that does not communicate.
3. Inspect for a proper connection at the serial data line terminals.

Repair as necessary.

4. If OK, measure the resistance from the data link connectors to the module harness connector.

Does the resistance measure within the specified range?

0-5 ohms

Go to Step 8

Go to Step 9

7 |

1. Turn the ignition switch off.
2. Disconnect the scan tool.
3. Connect a test lamp between the data link connector and the battery power.

Does the test lamp light?

--

Go to Step 10

Go to Step 11

8 |

1. Inspect for power and ground to the module.
2. If OK, replace the module.

Is the repair complete?

--

System OK

--

9 | Repair the open in the serial data circuit. Is the repair complete? | -- | System OK | --
10 |

1. Turn the ignition switch off.
2. Disconnect all of the modules that are connected to the terminals.
3. Measure the resistance on the data link connector from the terminals.

Does the DMM display OL (infinite)?

--

Go to Step 12

Go to Step 13

11 | Repair the open in CKT 451. Is the repair complete? | -- | System OK | --
12 |

1. Turn the ignition switch on.
2. Measure the voltage on the data link connector from the terminals.

Is any voltage measured?

--

Go to Step 14

Go to Step 15

13 | Repair the short from the serial data line to ground. Is the repair complete? | -- | System OK | --
14 |

1. Turn the ignition switch off.
2. Repair the short from the serial data line to voltage.

Is the repair complete?

--

System OK

--

15 |

1. Turn the ignition switch off.
2. Reconnect the disconnected module.
3. Turn the ignition switch on.
4. Establish communication.

Replace the most recently connected module if communication cannot be established.

5. Repeat this procedure until the malfunctioning module is isolated and repaired.

Did you establish communication?

--

System OK

--