ECM:- The Engine Control Module (also called the Powertrain Control Module or PCM) is the brains of the engine management system. It controls the fuel mixture, ignition timing, variable cam timing and emissions control. It constantly monitors emissions performance via its OBD (Onboard Diagnostics) programming, and it oversees the operation of the fuel pump, engine cooling fan and charging system. It also interacts with the transmission controller (if separate), ABS/traction/stability control system, body control module, climate control module and anti-theft system. In short, the engine control module performs a wide variety of functions that are necessary to operate a vehicle.
The electronic components inside an engine control modules are fairly robust, but sometimes things can and do go wrong. Shorts in sensor circuits may overload and damage the module. Problems with the module’s power supply (too much voltage or not enough) or ground connections can cause it to misbehave. Bad inputs from sensors or other modules may also cause it to malfunction. Corrosion, excessive heat and vibration also can cause harm to the module.
When an engine control module fails, it may or may not set any Diagnostic Trouble Codes (DTCs). This can make troubleshooting difficult and often results in misdiagnosis of a bad computer. Often the real problem is outside the computer such as a bad sensor, wiring fault, power relay or voltage issue. Complete module failures are rare, but failures within the module’s various subsystems and memory are more common. A shorted fuel injector, for example, may overload and burn out the injector driver circuit within the engine control module. If the underlying cause is not found and fixed, it can cause the replacement computer to fail, too.
1. The throttle position sensor (TPS) is used to control the shifting in an automatic transmission.
2. The manifold pressure sensor tells the engine control module how much power the engine is putting out.
3. The coolant temperature sensor calculates proper fuel delivery and ignition timing.
4. The measurement of outside air entering the engine is regulated by the mass air flow sensor.
5. The crankshaft positions sensor calculates the cylinder position and the engine speed.
6. The detonation sensor is used by the control module to regulate the ignition timing.
7. The oxygen sensor works to produce voltage based on the amount of oxygen in the engine's exhaust.
8. The intake air temperature sensor uses information about temperature to control a vehicle's fuel delivery.
9. EGR sensors adjust fuel delivery and control and help to provide diagnostic information to the control module.