Input Signals: Notes

Computer furnishes input sensors with a reference voltage (5 volts). This voltage signal is then modified by the resistance value of the sensors in each circuit. Some sensors are simple mechanical resistors, while others are temperature sensitive resistors (thermistors). ECU monitors either reference line or return signal to determine status of each sensor. Not all input signals are obtained from sensors. Some input signals are simply monitored circuits which either produce a voltage of their own (O2 and pick-up coils or already have a voltage signal present.