Using Check Mode With A Scan Tool

Check mode can be used to increase the ability of the powertrain control module (PCM) to detect engine control system malfunctions. The PCM can be requested to operate in check mode by using the Output Controls feature of the scan tool. While in check mode operation the PCM will turn ON the MIL and record freeze frame data even on the first failure of a B type DTC. In order to benefit from the enhanced diagnostics of check mode operation, perform the following procedure:
1. Capture or save any DTCs or Freeze Frame information on the scan tool before entering check mode operation. All DTC and Freeze Frame information will be cleared by the PCM when check mode is entered.
2. Enter check mode operation with a scan tool from the Special Functions selection. Check that the MIL is flashing which indicates that the check mode request was received and accepted. Return to the Data List selection on the scan tool.
3. DO NOT TURN OFF the ignition after requesting check mode operation with a scan tool. The PCM will return to normal operation when the ignition is cycled ON to OFF to ON.
4. Start and operate the vehicle (without cycling the ignition switch) within the conditions under which the original concern was noted or within the Freeze Frame conditions that set the DTC.
5. DO NOT TURN OFF the ignition anytime during or after the operation of the vehicle in check mode. Observe or capture all check mode operation DTCs or Freeze Frame information on the scan tool before turning OFF the ignition. Any DTCs or Freeze Frame information that occurred during check mode operation will be cleared by the PCM when the ignition is turned OFF.