Introduction to On Board Diagnostics (II)

Fundamentals of PowertrainControl strategies & OBD IIDiagnosticsFor more detailed information on all the request modes that you can use to performOBD II diagnostics using OBD II communications, and Scan Tool (SAE J 1978) , refer tothe HS -3000 SAE standards manual.The powertrain control strategies to perform OBD II diagnostics in general are described so far.Now the specific diagnostics performed for DTCs of the sensors, actuators, and systemsindicated below will be briefly described.Manifold absolute pressure (MAP) sensor (DTCs(105 - 109): MAP sensor diagnostics areperformed for deterioration of piezoresister or capacitor characteristics. In case of electricalcircuit malfunction fault code 105 is assigned. If the sensor is indicating out of range reading faultcode 106 is assigned. If the sensor is indicating very low reading fault code 107 is assigned. If thesensor is indicating very high reading fault code 108 is assigned. The expected value is estimatedusing mass air flow sensor reading and engine parameters. If the tsensor is indicatingintermittent faulty reading, fault code 109 is assigned.Intake air temperature (IAT) sensor (DTCs(110-114):114): IAT sensor diagnostics are performed fordeterioration of thermister characteristics. In case of thermister circuit malfunction fault code 110is assigned. If the sensor is indicating out of range reading fault code 111 is assigned. Theexpected value is estimated using coolant temperature sensor reading rand engine parameters. Ifthe sensor is indicating very low reading fault code 112 is assigned. aIf the sensor is indicatingvery high reading fault code 113 is assigned. If the sensor is indicating intermittent faultyreading fault code 114 is assigned.