Toronado V6-3800 3.8L (1988)
Engine Control Module: Description and Operation
Powertrain Control Module (PCM)
The Electronic Control Module (ECM) is the control center for the Sequential Fuel Injection (SFI) system and ignition system. The ECM constantly
monitors information from various data sensors and controls output devices that affect vehicle performance. The computer can control these devices
through the use of Quad Driver Modules (QDM). When the ECM is commanding a device or a component "ON," the voltage potential of the output is
low or near zero volts. When the ECM is commanding a device or component "OFF," the voltage potential of the circuit will be "HIGH," or near 12.0
volts. The primary function of the QDM is to supply the ground for the component being controlled. The input information has an interrelation between
sensor output. If one of the input devices fails, such as the oxygen sensor, this could affect more than one of the systems controlled by the computer.
To allow one type of ECM to be used for many different vehicles, a device called a Memory-Calibration (MEM-CAL) unit is used. The MEM-CAL
(PROM) is located inside the ECM and has system calibration information based upon the vehicle's axle ratio, engine, transmission, weight, and other
specific configurations of the vehicle. Since the MEM-CAL unit is unique to specific vehicles, it is important to install the MEM-CAL unit into the new
ECM when servicing. The ECM also has self-diagnostic functions which stores trouble codes and alerts the driver through a warning lamp on the
instrument panel.
