MPI <4G6> -
Troubleshooting
13A-72
INSPECTION PROCEDURE 30
A/C switch and A/C relay system
Probable cause
When
an
A/C
ON
signal
is
input
to
the
engine-ECU
<M/T>
or
engine-A/T
-ECU
<A/T>,
the
engine-ECU
<M/T>
or
engine-A/T
-ECU
<A/T>
carries
out
control
of
the
idle
speed
control (ISC) servo, and also operates the A/C compressor magnetic clutch.
D
Malfunction of A/C control system
D
Malfunction of A/C switch
D
Improper connector contact, open circuit or
short-circuited harness wire
D
Malfunction of the engine-ECU <M/T> or
Check the A/C compressor relay.
(Refer to GROUP 55 - On-vehicle Service.)
NG
Replace
OK
Measure at the engine-ECU connectors C-34, C-36 <M/T> or
the
engine-A/T
-ECU
connectors
C-175,
C-177
<A/T>.
D
Disconnect the connector, and measure at the harness side.
D
V
oltage
between
8
<M/T>,
20
<A/T>
and
earth,
and
45
<M/T>,
(Ignition switch: ON)
OK:
0 - 3 V (A/C switch: OFF)
System voltage (A/C switch: ON)
D
Short
circuit
between
8
<M/T>,
20
<A/T>
and
earth
(Ignition switch: ON, A/C switch: ON)
OK:
A/C compressor clutch turns on.
NG
Check the A/C system. (Refer to GROUP 55 - Troubleshooting.)
OK
Check the following
connectors:
M/T: C-34, C-36
A/T: C-175, C-177
NG
Replace
OK
Check trouble symptom.
NG
Replace
the
engine-ECU
<M/T>
or
engine-A/T
-ECU
<A/T>.
INSPECTION PROCEDURE 31
Ignition circuit system
Probable cause
The
engine-ECU
<M/T>
or
engine-A/T
-ECU
<A/T>
interrupts
the
ignition
coil
primary
currentbyturning thepowertransistorinsidetheengine-ECU<M/T>orengine-A/T-ECU
<A/T> ON and OFF.
D
Malfunction of ignition coil.
D
Malfunction of ignition failure sensor.
D
Improper connector contact, open circuit or
short-circuited harness wire
D
Malfunction of the engine-ECU <M/T> or
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