To understand pulse width modulation requires basic electrical understanding. In electric pumps, there are typically two settings – on and off. Simply put, a pump is on when it receives electrical power and it’s off when there is no power. When it’s on, it’s also known as 100% duty cycle.
In Part 1, we began to discuss the importance of oxygen sensor voltage codes. Voltage codes can be caused by sensors that are bad and stuck lean or rich. These codes can also be caused by lean or rich running conditions. The case studies we will focus on will look at pre-cat oxygen sensor codes, both caused by parts other than the O2 sensors.
The development of the automatic transmission is one of the most important milestones in the history of automobiles. The automatic transmission allowed for a much wider user base than had ever been dreamed of before.
The powertrain control module (PCM), which controls virtually every function of the engine and automatic transmission, depends upon an input signal from the TPS (among other things) to calculate fuel delivery and ignition timing strategy.