Passport 2WD V6-3.2L SOHC (6VD1) (1995)
Engine Control Module: Description and Operation
95 1/2 Model
DESCRIPTION
The Engine Control Module (ECM), located under the center of the dash, is the control center of the Fuel Injection system. If constantly looks at
the information from various Sensors, and controls the Systems that affect Vehicle performance. The ECM also performs the diagnostic function
of the system. It can recognize operational problems, alert the driver through the Malfunction Indicator Lamp, and store a Diagnostic Trouble
Code or Diagnostic Trouble Codes which identify the problem areas to aid the technician in making repairs. For service, this ECM is replaced as a
complete unit. There are no serviceable parts in the ECM. The Calibrations are stored in the ECM in the Electronic Erasable Programmable Read
Only Memory (EEPROM).
FUNCTION
This ECM supplies either 5 to 12 volts to power various Sensors or Switches. This is done through resistances in the ECM which are so high in
value that a Test light will not light when connected to the Circuit. In some cases, even an ordinary shop Voltmeter will not give an accurate
reading because its resistance is too low. Therefore, a 10 Megohms Input Impedance Digital Voltmeter is required to assure accurate voltage
readings. The ECM controls output Circuits such as the Fuel Injectors, Idle Air Control Valve, Air Conditioning Clutch Relay, etc. by controlling
the ground Circuit through Transistors or a device called a "Quad-Driver".