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mands the Idle Air Control (IAC) Motor to a specific PCM outputs monitored for functionality include: • Ignition Coils • Idle Air Control • Purge Solenoid • LDP Solenoid • Radiator Fan Control OXYGEN SENSOR (O2S) MONITOR DESCRIPTION—Effective control of exhaust emissions is achieved by an oxygen feedback system. The information obtained by the sensor is used to calculate the fuel injector pulse width. The PCM is The O2S is also the main sensing element for the Catalyst and Fuel Monitors. The O2S may fail in any or all of the following manners: • Slow response rate (Big Slope) • Reduced output voltage (Half Cycle) • Heater Performance is the time required for the sensor to switch from Reduced Output Voltage (Half Cycle)—The output voltage of the O2S ranges from 0 to 1 volt. A difficulty changing beyond the threshold value. Each Heater Performance—The heater is tested by a separate monitor. Refer to the Oxygen Sensor Heater OPERATION—As the Oxygen Sensor signal switches, the PCM monitors the half cycle and big The Oxygen Sensor Monitor is a two trip monitor that is tested only once per trip. When the Oxygen when the Oxygen Sensor monitor passes in three consecutive trips. The DTC is erased Enabling Conditions—The following conditions must typically be met for the PCM to run the oxygen • Battery voltage • Engine temperature • Engine run time • Engine run time at a predetermined speed • Engine run time at a predetermined speed and throttle opening • Fuel system in Closed Loop • Long Term Adaptive (within parameters) • Engine at idle • Fuel level above 15% • Ambient air temperature • Barometric pressure • Engine RPM within acceptable range of desired idle Pending Conditions—The Task Manager typi- cally does not run the Oxygen Sensor Monitor if over- monitors are running or the MIL is illuminated for any of the following: • Misfire Monitor • Front Oxygen Sensor and Heater Monitor • MAP Sensor • Vehicle Speed Sensor • Engine Coolant Temperature Sensor • Throttle Position Sensor • Engine Controller Self Test Faults • Cam or Crank Sensor • Injector and Coil • Idle Air Control Motor • EVAP Electrical • Intake/inlet Air Temperature • 5 Volt Feed 25 - 2 EMISSIONS CONTROL ZB EMISSIONS CONTROL (Continued) |