Description
All OBD II scan tools display the On-Board System Readiness (OSR) Test. The OSR will display the supported monitors on the vehicle and the status of all monitors (complete or not complete) at that time. Fuel, misfire and comprehensive component monitors run continuously and will always display "CONT" status. Only a PCM reset or a keep alive RAM reset will cause the non-continuous monitors to reinitialize to "NO" status.
Freeze Frame Data allows access to emission-related values from specific generic PIDs. These values are stored the instant an emission-related DTC is stored in Continuous Memory. This provides a snapshot of the conditions that were present when the DTC was stored. Once one set of freeze frame data will remain in memory even if another emission-related DTC is stored, with the exception of Misfire or Fuel System DTCs. Once freeze frame data for Misfire or Fuel System DTC is stored, it will overwrite any previous data, and freeze frame will not be further overwritten. When a DTC associated with the freeze frame is erased or a PCM memory reset is performed, new freeze frame data can be stored again. In the event of multiple emission-related DTCs in memory, always note the DTC for the freeze frame data.
The Output Test Mode (OTM) aids in servicing output actuators associated with the PCM. This mode allows the technician to energize and de-energize most of the system output actuators on command. When entering OTM, the outputs can be turned off and on without activating the fan control. The low and high speed fan control(s) may be turned on separately without energizing the other outputs. This function is supported by the WDS or equivalent and may not be available on all generic scan tools.
As a safety precaution, Output Test Mode will default to its normal state after 10 minutes, after the vehicle is started or after cycling the key off then on.
| WARNING | Safety must be observed when using output test mode: When all outputs are on, the electric fuel pump is briefly energized, so make sure fuel system is intact and is not being serviced at this time. When low speed or high speed fan control(s) are turned on, make sure fan blades are clear of any obstruction. |
All OBD II scan tools support the 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.
The following events occur when a PCM reset is performed
- Clears the number of 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. This function is performed only after retrieval of continuous DTCs.