The powertrain used in this vehicle consists of a
twin cam V6 engine mated to a 4T65-E
electronically controlled transaxle. The powertrain
has electronic controls to reduce exhaust emissions
while maintaining excellent driveability and fuel
economy. The powertrain control module (PCM) is
the heart of this control system.

The powertrain control module is designed to
maintain exhaust emission levels to Federal or
California standards while providing excellent
driveability and fuel efficiency. Review the
components and the 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
•  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 the 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 module stores a
diagnostic trouble code (DTC). The problem area is
identified by the particular DTC that is set. The
module supplies a buffered voltage to various
sensors and switches. The input and output
devices in the control module include analog to
digital converters, signal buffers, counters, and
output drivers. The output drivers are electronic
switches which complete a ground 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.
3.5L V6 Engine Computer (PCM) Description

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