MPI <4G63>
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Troubleshooting
13D-85
IDLE SPEED CONTROL (ISC) SERVO (STEPPER
MOTOR)
Measurement Method
1.
Disconnect the ISC servo connector, and connect the
special tool test harness (MB991709) in between.
2.
Connect the oscilloscope special patterns pickup to the
ISC servo side connector terminal No. 1, No. 3, No. 4
and No. 6 respectively.
Alternate Method (Test harness not available)
1.
Connect the oscilloscope special patterns pickup to
engine-A/T-ECU terminal No. 14, connection terminal No.
15, connection terminal No. 28, and connection terminal
No. 29 respectively.
Standard wave pattern
Observation conditions
Function
Special patterns
Pattern height
High
Pattern selector
Display
Engine condition
When the engine coolant temperature is 20
˚
C or below, turn the ignition switch from ”LOCK”
(OFF) position to ”ON” (without starting the engine).
While the engine is idling, turn the A/C switch to ON.
Immediately after starting the warm engine.
Special
patterns
pickup
Oscilloscope