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Home >> Mercury Truck >> 1997 >> Villager V6-181 3.0L SOHC VIN 1 EFI >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Testing and Inspection >> Monitors, Trips, Drive Cycles and Readiness Codes >> Description of Drive Cycles

Description of Drive Cycles

RELATIONSHIP BETWEEN MIL, DTC AND DETECTABLE ITEMS
- When a malfunction is detected for the first time, the Diagnostic Trouble Code (DTC) and the Freeze Frame Data are stored in the Powertrain Control Module (PCM) memory.
- When the same malfunction is detected in two consecutive trips, the Malfunction Indicator Lamp (MIL) will come on.
- The MIL will go off after the vehicle is driven three times with no malfunction. The drive is counted only when the recorded driving pattern is met (as stored in the PCM). If another malfunction occurs while counting, the counter will reset. The MIL will remain on until the vehicle is driven (in the recorded driving pattern) three times with no malfunction.
- The DTC and the Freeze Frame Data can be displayed until the vehicle is driven 40 times (except for Misfire and Fuel Injection System). For Misfire and Fuel Injection System, the DTC and freeze frame data can be displayed until the vehicle is driven 80 times.

TRIP
A Trip is defined as a Key-ON, Key-OFF event in which the PCM detects the following:
- Engine coolant should exceed 70°C (158°F).
- Engine coolant temperature should change more than 20°C (68°F) after starting the engine.
- Engine speed should go over 400 RPM.

When the PCM detects an emission related DTCs it uses the trip information to make its decision on whether to illuminate the MIL light.

INSPECTION/MAINTENANCE TESTING - OBD II SYSTEM READINESS MONITORS
In some areas of the country, it may become a legal requirement to pass an Inspection/Maintenance (I/M) test of the OBD II system. Before I/M testing can proceed, the OBD II drive cycle must be performed and all of the diagnostic monitors completed successfully. During the mix of city and highway driving involved in the OBD II drive cycle, the diagnostic monitors will test certain parts of the OBD II software and hardware used to control vehicle emissions. While some of the monitors will run to completion and indicate a YES or NO, others such as Misfire or Fuel System will continuously run.

OBD II Monitors:





If a fault exists in the system being monitored, a DTC will be stored in the PCM memory. Depending on the type of fault detected, some DTCs will command the MIL to illuminate immediately. Other faults will cause the PCM to store the DTC in memory along with freeze frame information but will not illuminate the MIL until the fault is detected again on a subsequent trip (2nd trip). Anytime a DTC is set in the PCM memory or a repair is made and DTCs are cleared from the PCM memory, the I/M ready monitors will reset to "No." To reset the I/M monitors to a ready status, the OBD II Drive Cycle must be performed.

OBD II DRIVE CYCLE
Follow the steps in order, if a step is interrupted, repeat the preceding step. Any safe driving mode is acceptable between steps. Do not shut the engine off until step 2 is completed.

NOTE: The PCM must see a change of at least 35°C (72°F) increase in the engine coolant temperature from the time the engine is started until it reaches operating temperature 70°C (158°F) before proceeding with the drive modes of the OBD II drive cycle.

1. After coolant temperature reaches operating temperature 70°C (158°F), idle the engine for 2 minutes.
2. Accelerate at a steady rate (1/4 to 1/2 throttle) until the vehicle reaches 55 mph (88 km/h), release the accelerator pedal for at least 10 seconds, allow the vehicle speed to drop and then quickly depress the accelerator pedal and accelerate to 53-60 mph (85-96 km/h). Drive the vehicle at a steady speed of 53-60 mph (85-96 km/h) for 5 minutes.

NOTE: The accelerator pedal must be held very steady during step 2 (driving at 53-60 mph [85-96 km/h]), or the test must be repeated.

3. Stop the vehicle and turn the engine off, wait at least five seconds.
4. Accelerate at a steady rate until the vehicle speed reaches 30-35 mph (50-55 km/h), drive at this speed for 20 seconds, stop the vehicle. Repeat step 4; ten times, if the Exhaust Gas Recirculation (EGR) system readiness test does not show "Yes", repeat steps 3 and 4.

NOTE: For step 4, the Throttle Position (TP) sensor voltage must remain between 0.8 volts and 1.2 volts during acceleration. Constant and slow acceleration is important when accelerating the vehicle during this test.

5. Accelerate smoothly until the vehicle speed reaches 50-55 mph (80-90 km/h) and drive the vehicle at this speed for 4 minutes.

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