Contents: Intake Components ↧ Release components ↧ Passive and active diagnostic tests ↧ Aggressive tests ↧ Warm-up cycle ↧ Crash data ↧
Comprehensive component diagnostics are required to check the powertrain components for intake and exhaust.
Intake Components
The intake components are monitored for continuity and out of tolerance values. Rationing is also checked. The rationalization test is designed to detect a malfunction if the sensor signal is abnormal, i.e. the throttle position sensor detects a high throttle position at low engine loads or the manifold absolute pressure (MAP) sensor voltage.
Intake components may contain these and other sensors.
- Vehicle Speed Sensor (VSS).
- Crankshaft position sensor (CPS).
- Throttle position (TP) sensor.
- Coolant temperature sensor (ECT).
- Camshaft position sensor (CMP).
- Manifold Absolute Pressure (MAP) sensor.
In addition to checking circuit integrity and rationalization, the ECT sensor is tested for its ability to achieve a constant temperature to ensure closed loop fuel control.
Release components
Exhaust components are diagnosed for compliance with control unit command feedback. Components for which functional diagnostics are not possible will be diagnosed for circuit integrity and out-of-tolerance data.
The following and other exhaust components are subject to diagnostics.
- Idle Air Control (IAC) stepper motor.
- Control unit, EVAP tank evaporative release valve.
- Air conditioner relay.
- Fan relay.
- VSS output.
- Malfunction Indicator Light (MIL) Controller.
Passive and active diagnostic tests
A passive test is a diagnostic that simply monitors a vehicle system or component. Conversely, an active test is a diagnostic action taken, often as a result of a passive test failing. For example, an active EGR test will cause the EGR valve to open during braking with the throttle closed and/or cause the EGR valve to close steadily. Each of these conditions will affect manifold pressure.
Aggressive tests
Any of the on-board tests performed by the diagnostic system that affect vehicle performance or emissions.
Warm-up cycle
The warm-up cycle means that the engine temperature must reach a minimum of 70°C and rise to a minimum of 22°C after the trip. The boundary data is an element of the diagnostic system where various data about the car is stored at the time of storing the emission system failure and when the command to turn on the malfunction indicator is given. This data will help to find the cause of the problem.
Crash data
Failure data is an extended function of boundary data. Failure data stores the same vehicle information as boundary data, but this information is stored for each failure in the on-board memory, while boundary data only stores emissions system failures, and a command is given to turn on the malfunction indicator lamp.
(Original version of the article on the website «CHEVYMAN.ru»)