GM Service Manual Online
For 1990-2009 cars only

Clearing DTCs: To prevent any future misdiagnosis, all history DTCs should be cleared after diagnosing a system problem.

Disconnecting the battery or module connectors will not clear a history DTC. A DTC can only be cleared by one of the following methods:

    • A scan tool.
    •  A module will clear a history DTC after 50 ignition cycles.

Most of the diagnostic tables will refer to the scan tool for diagnostic support.