OTC Tools Code Scanner Manual Del Usuario página 65

Variable Control Relay
Module. Contains
electronic switches to
control power to A/C clutch,
engine cooling fan, fuel
pump, etc. ECA controls
module. A 2-wire DCL
circuit carries ECA
instruction signals to a
computer circuit inside
VCRM. Power delivered by
VCRM can be adjusted so
that, for example, engine
fan can be slowly turned on
or run at various speeds.
(EEC-IV systems): Variable
Reluctance Sensor. A
sensor mounted on the
crankshaft which sends a
frequency type signal to the
ECA. The ECA uses VRS
to obtain information on
crankshaft position and
speed.(MCU systems):
Vacuum Regulator
Solenoid. Used with
feedback carburetors
having a vacuum controlled
fuel metering system.
(Feedback carburetors let
the engine computer
control air/fuel ratios.) The
MCU module sends a duty
cycle signal to VRS which
controls vacuum applied to
the fuel metering rod in the
carburetor. (See Duty
Cycle definition.) A low duty
cycle signal reduces
control vacuum for "rich"
operation.
A high duty cycle signal
increases control vacuum
for "lean" operation.
Vehicle Speed Sensor.
This sensor, mounted in
the transmission, sends a
frequency signal to the
ECA. The frequency
increases as the vehicle
moves faster to give the
ECA vehicle speed
information.
Voltage Variable Choke
actuator. Used on feedback
carburetors in MCU
systems. The MCU module
sends a duty cycle type
signal to this actuator in
order to control the amount
of choke opening. (See
Duty Cycle definition.)
Wide-open-throttle Air
conditioner Cut-off relay.
Used by the ECA to turn off
the A/C clutch and thus
reduce engine loading. This
is desirable during heavy
acceleration, engine cranking
or engine overheating
conditions.
Wide Open Throttle. The
vehicle operating condition
brought about when the
throttle is completely (or
nearly so) open. The ECA
typically delivers extra fuel to
the engine at this time for
acceleration purposes. The
ECA uses the Throttle
Position sensor to identify the
WOT condition.
65
Wide Open Throttle
Vacuum Switch. Used on
MCU systems. The switch
is closed when applied
vacuum is weak, and open
when vacuum is strong. The
MCU module detects WOT
operation when the weak
manifold vacuum present
during WOT conditions
causes the vacuum switch to
close. The MCU module
provides extra fuel at this
time for acceleration
purposes.
Used in some
Microprocessor Control Unit
(MCU) systems. These three
switches are used to detect
low, medium and high
vacuum levels in the intake
manifold. They send electrical
signals to the MCU module.
The MCU module can then
calculate throttle position and
engine load.