Actron CP9035 Insrucciones página 49

Powertrain Control Module. The
"brains" of the engine control system. It
is a computer housed in a metal box
with a number of sensors and actua-
tors connected with a wiring harness.
Its job is to control fuel delivery, idle
speed, spark advance timing, and
emission systems. The PCM receives
information from sensors, then
energizes various actuators to control
the engine. The PCM is frequently
called the ECM (Engine Control
Module).
PROM:
Programmable Read-Only Memory.
The PROM contains permanent
programming information the PCM
needs to operate a specific vehicle
model. Included are vehicle weight,
engine and transmission type, axle
ratio, and other specifics.
Purge Solenoid:
This device controls the flow of fuel
vapors from the carbon canister to the
intake manifold. The canister collects
vapors evaporating from the fuel tank,
preventing them from escaping to the
atmosphere and causing pollution.
During warm engine cruise conditions,
the PCM energizes the Purge Solenoid
so the trapped vapors are drawn into
the engine and burned.
Relay:
An electric/mechanical device for
switching high current circuits on and
off. It is electronically controlled by a
low current circuit. Relays allow a low
power PCM signal to control a high
power device such as an electric
cooling fan.
Reluctance Sensor:
Crankshaft or Camshaft - Speed,
position (for spark timing or fuel
injector control). Driveshaft - Vehicle
speed (transmission or torque
converter control, cooling fan use,
variable assist power steering, and
cruise control). Wheel Speed - Anti-
REFERENCE GLOSSARY
lock brakes or traction control systems
ROM:
Read-Only Memory. Permanent
programming information stored inside
the PCM, containing the information the
PCM needs to operate a specific
vehicle model.
Sensor:
Devices which give the PCM informa-
tion. The PCM can only work with
electrical signals. The job of the sensor
is to take something the PCM needs to
know, such as engine temperature, and
convert it to an electrical signal that the
PCM can understand. The PCM uses
sensors to measure such things as
throttle position, coolant temperature,
engine speed, incoming air mass and
temperature, etc.
SFI or SEFI:
Sequential Fuel Injection or Sequential
Electronic Fuel Injection. A fuel injection
system that uses one or more injectors
for each cylinder. The injectors are
mounted in the intake manifold, and are
fired individually in the same sequence
as the spark plug firing order.
Shift Solenoid:
Used in computer controlled transmis-
sions, the solenoids (usually two) are
located in the transmission housing
and are controlled by the PCM. The
PCM energizes the solenoids individu-
ally, or in combination, to select a
specific gear. The solenoids control the
flow of hydraulic fluid to the transmis-
sion shifting valves. The PCM selects
the appropriate gear ratio and shift
point based on engine operating
conditions.
Solenoid:
A solenoid is a device to convert an
electrical signal to mechanical
movement. It consists of a coil with a
wire and a moveable metal rod in the
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