The PCM is designed to maintain exhaust emission levels to Federal/California/other
standards while providing excellent driveability and fuel efficiency. Review the components
and wiring diagrams in order to determine which systems are controlled by the PCM. The
PCM monitors numerous engine and vehicle functions. The following are some of the
functions that the PCM controls:
• The engine fueling
• The ignition control (IC)
• The knock sensor (KS) system
• The evaporative emissions (EVAP) system
• The secondary air injection (AIR) system (if equipped)
• The exhaust gas recirculation (EGR) system
• The automatic transmission functions
• The generator
• The A/C clutch control
• The cooling fan control
Powertrain Control Module Function
The PCM constantly looks at the information from various sensors and other inputs and
controls systems that affect vehicle performance and emissions. The PCM also performs
diagnostic tests on various parts of the system. The PCM can recognize operational
problems and alert the driver via the malfunction indicator lamp (MIL). When the PCM
detects a malfunction, the PCM stores a diagnostic trouble code (DTC). The problem area is
identified by the particular DTC that is set. The control module supplies a buffered voltage
to various sensors and switches. The input and output devices in the PCM include analog-to-
digital converters, signal buffers, counters, and output drivers. The output drivers are
electronic switches that complete a ground or voltage circuit when turned on. Most PCM
controlled components are operated via output drivers. The PCM monitors these driver
circuits for proper operation and, in most cases, can set a DTC corresponding to the
controlled device if a problem is detected.
How to scan for computer trouble codes
standards while providing excellent driveability and fuel efficiency. Review the components
and wiring diagrams in order to determine which systems are controlled by the PCM. The
PCM monitors numerous engine and vehicle functions. The following are some of the
functions that the PCM controls:
• The engine fueling
• The ignition control (IC)
• The knock sensor (KS) system
• The evaporative emissions (EVAP) system
• The secondary air injection (AIR) system (if equipped)
• The exhaust gas recirculation (EGR) system
• The automatic transmission functions
• The generator
• The A/C clutch control
• The cooling fan control
Powertrain Control Module Function
The PCM constantly looks at the information from various sensors and other inputs and
controls systems that affect vehicle performance and emissions. The PCM also performs
diagnostic tests on various parts of the system. The PCM can recognize operational
problems and alert the driver via the malfunction indicator lamp (MIL). When the PCM
detects a malfunction, the PCM stores a diagnostic trouble code (DTC). The problem area is
identified by the particular DTC that is set. The control module supplies a buffered voltage
to various sensors and switches. The input and output devices in the PCM include analog-to-
digital converters, signal buffers, counters, and output drivers. The output drivers are
electronic switches that complete a ground or voltage circuit when turned on. Most PCM
controlled components are operated via output drivers. The PCM monitors these driver
circuits for proper operation and, in most cases, can set a DTC corresponding to the
controlled device if a problem is detected.
How to scan for computer trouble codes
Powertrain Control Module ( PCM ) Electronic / Engine Control Module ( ECM )
WARNING LIGHTS
