Input Rationality

While input signals to the PCM are constantly being monitored for electrical opens and shorts, they are also tested for rationality. This means that the input signal is compared against other inputs and information to see if it makes sense under the current conditions.

PCM sensor and CAN Bus inputs that are checked for rationality include:

• Manifold Absolute Pressure (MAP) Sensor
• Oxygen Sensor (O2S) (slow response)
• Engine Coolant Temperature (ECT) Sensor
• Camshaft Position (CMP) Sensor
• Vehicle Speed from the Controller Antilock Brake (CAB)
• Crankshaft Position (CKP) Sensor
• Mass Air Flow (MAF)/Intake Air Temperature (IAT) Sensor
• Accelerator Pedal Position Sensor (APPS)
• Throttle Position Sensor (TPS)
• Knock Sensors
• Oxygen Sensor Heater
• Engine Controller
• Brake Switch
• Evaporative Vacuum Leak Detection (EVLD)
• P/N Switch
• Transmission Controls