On Board Diagnostics

Powertrain Handle Module (PCM) performs the following capabilities in relation to:

OBD II Diagnostics:

Perform micro-processor based mostly self diagnostics to assure right operation of the PCM and safe and sound storage of OBD II diagnostic information in memory.

Complete On-Board diagnostics in authentic time and notify the driver by illuminating MIL in case of a fault execute powertrain command functions to lessen emissions and meet up with OBD II polices through open-loop procedure at start-up time.

Accomplish powertrain control capabilities to reduce emissions and fulfill OBD II polices in closed-loop manage through regular operation.

Perform microprocessor-based mostly self diagnostics to make sure accurate operation of the PCM and harmless storage of OBD II diagnostic facts in memory.

The PCM performs the pursuing self diagnostics:

· Verify the checksum of the plan memory in ROM with its function and suitable edition.

· Perform browse and compose check of RAM cells for fault absolutely free memory Conduct processor features in CPU, peripheral equipment like A/D converters, watchdog timers, and registers to verify that the processor is working effectively.

· Carry out checks on stored car or truck details and verify that the facts is not corrupted and is in just reasonable limitations of auto operation.

· Perform On-Board diagnostics in serious time and notify the driver by illuminating MIL in circumstance of a fault, by interspersing diagnostics with car or truck control features.

The diagnostics are labeled into precedence levels from one to eight or 9. The highest priority amount tests are performed every single 1 millisecond, followed by upcoming priority level checks each and every five milliseconds, 10 milliseconds, 20 milliseconds, 50 milliseconds, 100 milliseconds, two hundred milliseconds, five hundred milliseconds, and one next. The best priority stage checks are those that influence security and emissions to a substantial degree in accordance to OBD II laws. These involve Oxygen sensor (lambda sensor), and gasoline trim checks during closed loop procedure of the motor vehicle. The upcoming priority checks are the interrupt timers, and watchdog timers.
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The next precedence exams are sensors, which include Ego sensor, Throttle posture sensor, Misfire detection, MAP sensor, Motor RPM sensor, MAF sensor, Crankshaft place sensor, and Motor coolant sensor. The upcoming priority checks are EGR intrusive tests, Catalytic converter’s secondary air, and canister purge, gasoline amount sensor, pedal actuator, and ignition timer. The up coming priority checks are periodic self exams.

The PCM performs on-board diagnostics in actual time The PCM is interrupted by the authentic time scheduler for the duration of the performance of its normal motor vehicle control functions when the on-board checks are owing. At this time the PCM will save its present-day point out of the automobile and performs the diagnostics. This usually takes about a hundred microseconds. Then the PCM returns to its normal car command functions. This repeats for every single precedence amount diagnostics. In this fashion the PCM spends about 15-40% of its time to diagnostics and the rest to perform its typical car or truck regulate functions.

The technique of tests each part depends on the electrical qualities and motor vehicle capabilities executed by the device. The PCM maintains the small and large boundaries for just about every check parameter, and usual assortment of values and functionality specifications for every single ingredient that it checks. The PCM also has sufficient hardware check ability to find a quick circuit, or open up circuit, or the sounds degree of a sign, together with battery, ability provide, wiring harness, each and every sensor, actuator and command device associated to emissions command.

The PCM checks each sensor by measuring each and every test parameter, such as enter, or output and comparing it with the predicted value stored in the technical info for the sensor.