Powertrain Control Module

The PCM, through various input sensors, monitors battery voltage, engine RPM, intake air volume, cranking signal, camshaft position, crankshaft position, intake air temperature, radiator and engine coolant temperatures, exhaust oxygen content, throttle position, EGR valve position, atmospheric pressure, gearshift lever position, clutch engagement, vehicle speed, braking, power steering operation, and A/C compressor operation.

The PCM utilizes this input information to control fuel injection system and operation of other output devices. Spark timing is also controlled by the PCM.

The PCM has a built-in fail-safe mechanism. If a fault occurs while driving, the PCM will substitute preprogrammed values. Driving performance will be affected, but vehicle may still be driven.

The PCM has a self-diagnostic function, which allows the module to store diagnostic trouble codes in its memory. A Malfunction Indicator Light (MIL), located on instrument cluster, informs driver of system problems.

ECM/PCM LOCATIONS

Application	Location
B2300, B3000, B4000 & Tribute	Passenger Side Of Cowl Area, Under Hood
Miata	Left Side Of Dashboard, Behind Brake Pedal Bracket
Millenia	Below Center Of Dashboard, Under Radio
MPV	Right Side Of Dashboard, Behind Air Duct
Protege & Protege5	Passenger Floor, Under Carpet
626	Below Front Of Center Console, Under Radio

NOTE: Components are grouped into 2 categories. The first category covers INPUT DEVICES, which control or produce voltage signals monitored by the PCM. The second category covers OUTPUT SIGNALS, which are components controlled by the PCM.