All OBDII scan tools support the powertrain control module (PCM) reset.

The PCM Reset allows the scan tool to command the PCM to clear all emission-related diagnostic information. When resetting the PCM, a DTC P1000 will be stored in the PCM until all the OBD II system monitors or components have been tested to satisfy a drive cycle, without any other faults occurring. For more information about a drive cycle, refer to Drive Cycles.

The following events occur when a PCM reset is performed:

• Clears the number of Diagnostic Trouble Codes (DTCs).
• Clears the DTCs.
• Clears the freeze frame data.
• Clears diagnostic monitoring test results.
• Resets status of the OBD II system monitors.
• Sets DTC P1000.

Note: When using the New Generation Star (NGS) Scan Tool to perform a PCM reset, press the CLEAR button. This function is performed only after retrieval of continuous DTC's.

Refer to the manufacturer's manual for specific instructions on how to perform PCM reset.

Resetting Keep Alive RAM will return PCM memory to its default setting. Adaptive learning contents such as idle and fuel trim are included. A PCM Reset (described above) is also part of a KAM Reset.

After Keep Alive RAM has been reset, the vehicle may exhibit certain driveability concerns. It will be necessary to drive the vehicle to allow the PCM to relearn values for optimum driveability and performance.

A Keep Alive Random Access Memory Reset is done as follows:

During key on, engine off with the scan tool, use the Reset Keep Alive Memory function. This is found in the Active Command Modes menu on the New Generation Star scan tool.

If a generic scan tool is used, this function may not be supported. Refer to scan tool manufacturer's instruction manual.

If an error message is received or the scan tool does not support this function, disconnecting the battery ground cable for a minimum of 5 minutes may be used as an alternative procedure.