CTS Wagon RWD V6-3.6L (2010)
Engine Control Module: Description and Operation
Engine Control Module Description
The Engine Control Module (ECM) interacts with many emission related components and systems, and monitors emission related components and
systems for deterioration. OBD II diagnostics monitor the system performance and a diagnostic trouble code (DTC) sets if the system performance
degrades.
Malfunction indicator lamp (MIL) operation and DTC storage are dictated by the DTC type. A DTC is ranked as a Type A or Type B if the DTC is
emissions related. Type C is a non-emissions related DTC.
The ECM is in the engine compartment. The ECM is the control center of the engine controls system. The ECM controls the following components:
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The fuel injection system
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The ignition system
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The emission control systems
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The on-board diagnostics
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The A/C and fan systems
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The throttle actuation control (TAC) system
The ECM constantly monitors the information from various sensors and other inputs, and controls the systems that affect vehicle performance and
emissions. The ECM also performs diagnostic tests on various parts of the system. The ECM can recognize operational problems and alert the driver via
the MIL. When the ECM detects a malfunction, the ECM stores a DTC. The condition area is identified by the particular DTC that is set. This aids the
technician in making repairs.
ECM Function
The ECM can supply 5 V or 12 V to various sensors or switches. This is done through pull-up resistors to regulated power supplies within the ECM. In
some cases, even an ordinary shop voltmeter will not give an accurate reading because the resistance is too low. Therefore, a DMM with at least 10
megohms input impedance is required in order to ensure accurate voltage readings.
The ECM controls the output circuits by controlling the ground or the power feed circuit through transistors or a device called an output driver module.
EEPROM
The electronically erasable programmable read only memory (EEPROM) is a permanent memory that is physically part of the ECM. The EEPROM
contains program and calibration information that the ECM needs in order to control powertrain operation.
Special equipment, as well as the correct program and calibration for the vehicle, are required in order to reprogram the ECM.
Theft Deterrent System Frequency Code Programming
