Summary of Monitor Information

OBDII Monitor Operation:

REAR WHEEL DRIVE VEHICLES
The following procedure has been established to assist Dealer Technicians in the field with enabling and running OBD II Monitors. The order listed in the following procedure is intended to allow the technician to effectively complete each monitor and to set the CARB Readiness Status in the least time possible.

NOTE:
A. Once the monitor run process has begun, do not turn off the ignition. By turning the ignition key off, monitor enabling conditions will be lost.
B. By performing a Battery Disconnect, or Selecting Erase DTC's, the CARB Readiness and all additional OBD information will be cleared.

MONITOR PRELIMINARY CHECKS
1. Plug scantool into the vehicle's DLC.
2. Turn the ignition, KEY ON - ENGINE OFF. Watch for MIL lamp illumination during the bulb check. MIL lamp must have illuminated, if not, repair MIL lamp.
3. With the scantool check for any DTC's
- Verify that No Emissions Related DTC's are Present and MIL is not illuminated.
- If an Emissions DTC is Present and the MIL is ON, the OBD II Monitors may not run and the CARB

Readiness will not update.
- The Emissions related DTC, which is causing the MIL, will need to be repaired, then cleared. By clearing DTC's, the OBD Monitors will need to be run and completed to set the CARB Readiness Status.
- Group 25 can assist in determining which faults will illuminate the MIL Lamp. With the scantool check for CARB Readiness Status:

Do all the CARB Readiness Status Locations read YES?
- YES, then all monitors have been completed and this vehicle is ready to be I/M or Emission Tested.
- NO, then the following procedures will aid in running and completing all available monitors.

MONITOR RUN PROCESS
Outlined below is the Monitor Run Process, including suggestions and tips in order to aid in the process of meeting the enabling criteria to allow any of these monitors to run.

NOTE:
The most efficient order has been outlined below. The first two monitors have very similar enable criteria. It is possible that the Evaporative Leak Detection Monitor will run during the O2 Sensor Heater Monitor.

1. O2 Sensor Heater Monitor
This monitor requires a cold start, usually an overnight soak or parked for at least 8 hours without the engine running. The engine coolant temperature must be within 10 degrees of ambient/battery temperature, and the sensed Ambient (outside temperature) must be between approximately 0 °F and 100 °F. For the monitor run conditions,

2. Evaporative Leak Detection Monitor (If the vehicle is equipped with an LDP system)
This monitor requires a cold start, usually an overnight soak or parked for at least 8 hours without the engine running. The engine coolant temperature must be within 10 degrees of ambient/battery temperature, and the sensed Ambient (outside) Temperature must be between approximately 40 °F and 90 °F. For the monitor run conditions select the EVAP LEAK PRE-TEST in the DRBIII, OBD II Monitors Menu.

3. Catalyst Monitor
The vehicle will need to be driven at highway speed for a few minutes (approximately 35 - 40 mph for 2.5L and 4.0L engines, 50 - 60 mph for all others). If the vehicle is equipped with a manual transmission, using 4th gear may assist in meeting the monitor running criteria. For the monitor run conditions, select the CATALYST PRE-TEST in the DRBIII, OBD II Monitors Menu.

4. O2 Sensor Monitor
The vehicle will need to be driven for a period of time (approximately 35 - 40 mph for 2.5L and 4.0L engines, 50 - 60 mph for all others) and brought to a stop for a short period of time (with the Automatic Transmission left in Drive. The O2 Monitor will not run in Park or Neutral on an Automatic Transmission equipped vehicle). For the monitor run conditions, select the O2 SENSOR PRE-TEST in the DRBIII, OBD II Monitors Menu.

5. Purge Monitor
The Purge Free (PF) cells must update on the PURGE FLOW PRE-TEST screen. For the enable conditions, select "F1" while looking at the PURGE FLOW PRE-TEST screen. Similar Test conditions as the O2 Sensor Monitor, that is, Normal Operating Temperature, come to a stop while leaving the Automatic Transmission in Drive (not Park or Neutral). The Purge Flow Monitor will attempt to run every OTHER Throttle Closure. If all of the parameters are met and it still does not run, with your foot firmly on the Service Brake, slightly (1/4) open the Throttle and quickly close the Throttle. This will allow the Purge Free update to happen, and then the Purge Flow Monitor will Run.