Reading Diagnostic Trouble Codes (DTCs) With a Scan Tool
The BCM does not turn the SERVICE ENGINE SOON malfunction indicator lamp (MIL) ON. The BCM turns the SECURITY malfunction indicator lamp (MIL) ON for Passlock™ system-related malfunctions. The recommended method for reading DTCs that are stored in the memory is to use a scan tool plugged into the DTC connector. The DTC connector is located under the instrument panel on the left side. Follow the scan tool instructions that are supplied by the tool manufacturer. The DTCs are stored in the memory of the body control module (BCM) as a current or a history DTC.
Current Codes
Important: The ignition switch should be in the OFF position when connecting or disconnecting the connectors to the BCM. Always disconnect the brown BCM connector FIRST and connect the brown BCM connector LAST. The BCM may set DTC(s) with the ignition switch in the OFF position. Disconnecting the battery or disconnecting the BCM connectors will NOT clear DTC(s). Disconnecting the BCM connectors may cause other DTC(s) to set due to a loss of power or ground to the BCM while the BCM is in the AWAKE mode.
The BCM sets the code as a current DTC when the following conditions exist:
| • | The BCM determines that the test conditions and failure conditions for a particular DTC are true. |
| • | The current wake up cycle is still in effect. |
All DTCs remain current until the following conditions exist:
| • | The next fault-free wake up cycle is performed. |
| • | The BCM finds the test conditions are true. |
| • | The BCM finds the failure conditions are false. |
The current code changes to a history code only when all of the above conditions are true.
History Codes
When a DTC reports a failure and the failure is not in the current wake up cycle, that DTC is stored as a history DTC code. The BCM performs internal diagnostic tests in order to acknowledge that the related systems have reported a pass or fail condition. Each diagnostic test that fails is recorded in the BCM memory. The BCM memory may be accessed with a scan tool in order to determine which DTC circuit is at fault.
Clear a history DTC by using one of the following methods:
| • | Complete 100 subsequent ignition cycles with no diagnostic test reporting a fail. |
| • | Use the scan tool. |
After Diagnosis is Complete
After you diagnose the problem and repair the discovered malfunction, clear any DTCs set and verify proper operation. In order to verify proper operation, duplicate the conditions when the customer's complaint occurred. If a DTC was set, duplicate the test conditions for that DTC. The test conditions are listed above the DTC table. Refer to Conditions for Setting the DTC. The DTC should not re-set after the repair has been completed.
