MPI <4G63>
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Troubleshooting
13D-64
INSPECTION PROCEDURE 32
Idle speed control (ISC) servo (Stepper motor) system
Probable cause
The engine-A/T-ECU controls the intake air volume during idling by opening and closing
the servo valve located in the bypass air passage.
D
Malfunction of the ISC servo
D
Improper
connector
contact,
open
circuit
or
short-circuited harness wire
D
Malfunction of the engine-A/T-ECU
Check the ISC servo
(Refer to P.13D-102.)
NG
Replace
OK
Measure at the ISC servo connector B-103.
D
Disconnect the connector and measure at the harness side.
D
Voltage between 2 and earth, and 5 and earth
(Ignition switch: ON)
OK:
System voltage
NG
Check the harness wire between control relay and ISC servo con-
nector, and repair if necessary.
OK
Measure at the engine-A/T-ECU connector C-122.
D
Disconnect the connector, measure at the harness side.
D
Voltage between each of 14, 15, 28, 29 and earth (Ignition
switch: ON)
OK:
System voltage
NG
Check
the
following
connector:
B-103
NG
Repair
OK
Check the trouble symptom.
NG
Check harness wire between engine-A/T-ECU and ISC servo con-
nector, and repair if necessary.
OK
Check
the
following
connector:
C-122
NG
Repair
OK
Check the trouble symptom.
NG
Replace the engine-A/T-ECU.