Input Signals

Fig 1: Identifying Engine Control Module (ECM) Input Signals

Courtesy of VOLVO CARS OF NORTH AMERICA.

The engine control module (ECM) receives signals describing running conditions from the following components: 

• engine speed and crankshaft position, from the engine speed (RPM) sensor at the flywheel (7/25)
• working cycle in cylinders, from the camshaft position (CMP) sensor (7/21)
• engine load, from the mass air flow (MAF) sensor (7/17)
• height above sea level from the atmospheric pressure sensor (7/95)
• outside temperature from the outside temperature sensor (7/105), certain markets only
• engine temperature, from the engine coolant temperature (ECT) sensor (7/16)
• throttle angle, from the throttle position (TP) sensor (7/54)
• oxygen content of the exhaust gases upstream of the catalytic converter, from the front heated oxygen sensor (HO2S) (7/15)
• oxygen content of the exhaust gases downstream of the catalytic converter, from the rear heated oxygen sensor (HO2S) (7/82)
• engine knock (if present), from the two knock sensors (KS) (7/23 and 7/24)
• vehicle speed, from the combined instrument panel (5/1)
• imminent gear shifting, from the automatic transmission control module (TCM) (4/28) (automatics only)
• gear selector lever in park/neutral or drive positions, from the automatic transmission control module (TCM) (4/28)
• malfunction indicator lamp (MIL) request from the automatic transmission control module (TCM) (4/28)
• vertical acceleration of the car from accelerometer (7/79) to determine if the car is being driven on an uneven road, misfire diagnostic
• if air conditioning (A/C) is selected, from the air conditioning (A/C) system control panel (3/54)
• air conditioning (A/C) compressor ON signal, from the pressure switch (Pressostat) (7/53)
• pressure in air conditioning (A/C) system, from the air conditioning (A/C) pressure sensor (7/8)
• pressure in fuel tank, from fuel tank pressure sensor (7/84), certain markets only