Maintenance Manual for Chery·Windcloud Marelli EFI System
9. Idle Speed Actuator Stepper Motor
DLA
Functions: there is also a bypath air passage
provided by idle speed actuator with stepper
motor. When throttle is shut, air enters
engine through this bypath air passage. ECU
controls the section area of this passage
through a stepper motor to control the intake
volume and fuel injection. When engine is
idling, increasing or decreasing the section
area of bypath air passage may increase or
decrease engine speed and achieve
closed-loop control of idle speed.
Composition and principle: Stepper motor
is a micro electrical machine, which consists
of several steel stators arranged in a circle
and a rotor. Each steel stator is covered by a
coil; rotor is a permanent magnet, center of
which fixed a nut. All stator coils are
electrified all the time. Once the current
direction of a coil is changed, the rotor will
rotate by an angle. When all stator coils are
changing their current directions in a proper
order, a rotating magnetic field is formed to
keep permanent magnet rotor rotating in a
certain direction.
Failure diagnosis: ECU can monitor short
circuit, open circuit status of two coils in
idle speed stepper motor, and lighten engine
failure lamp when such failure occurs, then
engine enters failure mode.
Hints: ECU diagnosing system only
monitors circuit of actuator, and it dose not
detect if the stepper motor actually
implements that command, i.e. it is possible
that ECU sends a command, and stepper
motor circuit has no problem, but stepper
motor is unable to implement the command
due to sticking. This situation may result in
unstable idling and flameout with no failure
code displayed.
Working voltage: 6-16V DC
Coil resistance: (1-4, 2-3) 53ohm at 23 ±5 ℃
Min. stroke ensured by pusher: 8.9 mm
(around 214 steps)
Idle speed actuator stepper motor
Idle speed stepper motor
Circuit diagram of idle speed actuator stepper
motor
Pins:
Pin 1 connects to ECU 64# pin;
Pin 2 connects to ECU 65# pin;
Pin 3 connects to ECU 57# pin;
Pin 4 connects to ECU 58# pin;
Troubleshooting: short circuit or open
circuit occurs to the four wires connecting
stepper motor and ECU;
Check if stepper motor gets stuck;
Check if short circuit or open circuit occurs
to stepper motor.
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