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Drive Cycles




Description
A drive cycle is a method of driving a vehicle to verify a driveability symptom or its repair. It can also be a method of driving a vehicle to initiate and complete a specific OBD II monitor. A drive cycle may be done in the service bay or may require specific drive modes such as a number of idle periods, steady vehicle speed per time, accelerations at certain throttle angles, etc.

Monitor (the OBD II Drive Cycle) Requirements

OBD II Drive Cycle:






SPECIAL NOTES

The engine on all vehicle applications except Escort/Tracer must be warmed up to an operating temperature of at least 180°F (82°C) before proceeding with the OBD II Drive Cycle (check ECT PID). The OBD II Drive Cycle for the Escort/Tracer must be initiated on a cold start or at an ECT reading of less than 100°F (45°C) to assure completion of the Evaporative Thermistor Flow Test (part of the Comprehensive Component monitor) and the Catalyst monitor. This temperature can be verified with the ECT PID on the Scan Tool. Do not turn the engine off or restart anytime during the OBD II Drive Cycle to clear DTC P1000. If a key off does occur, start the process from the beginning.

a. For Probe a drive or idle in neutral for 9 minutes in Step 1 and an idle in drive (neutral for M/T) for 2 minutes in Step 5 is necessary to satisfy conditions to initiate the Evaporative Emission Monitor.

b. For Escort/Tracer and Probe acceleration to no more than 35 MPH (M /T in 4th gear) and a steady throttle at that speed is required for HO2S Monitor completion.

c. The city drive 25 to 40 MPH (M/T in 3rd and 4th gear) must include the following driving modes:
- At least 5 stop and idle (A/T in drive and M/T in neutral) modes at 10 seconds each.
- Accelerations from idles at 1/4 to 1/2 throttle position (for Escort/Tracer use 1/2 to 3/4 throttle position).
- Choose 3 different speeds between 25 and 40 MPH (M/T in 3rd and 4th gear) to do a 15 minute steady state throttle drive.
- A steady state throttle between 25 and 40 MPH near the end of the 15 minute drive is required on the Probe to meet conditions to run the steady state portion of the Catalyst Monitor.

d. The Evaporative Emission Monitor may not initiate in ambient temperatures below 400°F and above 110°F. Both the Evaporative Emission Monitor and Misfire Detection Monitor do not have to initiate or complete in order to clear the DTC P1000.

e. The EGR Monitor on the Probe extends through the completion of the steady throttle drive at 50 to 60 MPH for 5 seconds.


The following conditions must occur to complete all OBD II monitors and components.

- The Misfire, Comprehensive Component, and Fuel Monitors are checked continuously from engine warm-up and can complete any time.

- The Misfire Monitor on applications with fuel deceleration shut-off requires a deceleration at closed throttle for 10 seconds following the acceleration to 55 mph at one quarter to one half throttle. Decelerations following an acceleration must be performed twice consecutively (or three consecutively on some truck applications) to satisfy this misfire requirement.

- A transmission component functional verification in the Comprehensive Component Monitor requires at least 6 complete stops in the normal city portion of the drive cycle.

- The EGR and Secondary Air Injection Monitors require a series of idles and accelerations.

- The HO2S Monitor requires a steady speed drive for approximately 1 minute at 30 to 40 mph.

- The Secondary Air Injection Monitor requires almost 12 minutes of vehicle operating time from initial start-up.

- The Catalyst Efficiency Monitor requires a steady speed drive for 5 minutes at 40 to 60 mph, followed by a normal city drive between 25 and 40 mph for 10 minutes.

- The Evaporative Emission Monitor requires at least 3 minutes of the steady throttle part of the drive cycle (10 minutes) between 45 to 60 mph to test the evaporative system.

OBD II Monitor Display on Scan Tool

The On-Board System Readiness function will be available on all Scan Tools. This function will indicate the status of each OBD II monitor. One Parameter Identification (PID) display on a New Generation Star (NGS) summarizes the status of all monitors.

OBD II Drive Cycle and Malfunction Indicator Lamp Function

When a malfunction is present for two consecutive drive cycles the MIL is turned On except for Steady State Catalyst Efficiency Monitor and Misfire Detection Monitor. The MIL is turned On for a Steady State Catalyst Efficiency Monitor malfunction after the malfunction is present for three consecutive drive cycles. When a misfire that would cause catalyst damage is detected the MIL will turn On or flash. If the misfire is the type that will cause an emission failure or an inspection maintenance failure the MIL will turn On after the malfunction is detected during the next drive cycle. The MIL is turned Off after three consecutive drive cycles without the same malfunction being detected provided no other DTCs are stored that would independently turn the MIL On. The actual number of drive cycles necessary to control the MIL varies with each monitor.

OBD II Drive Cycle and Diagnostic Trouble Codes

A Diagnostic Trouble Code (DTC) will be stored in PCM memory after a malfunction is first detected. A DTC will be erased from the PCM's memory after 40 engine warm-up cycles without the malfunction being detected after the MIL is turned off. Another method of erasing the DTC is initiating a PCM reset. DTC memory storage requirements vary with each monitor.
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