Oscilloscope Testing

IDLE AIR CONTROL (STEPPER) MOTOR INSPECTION PROCEDURE USING AN ANALYZER

Measurement Method

1. Disconnect the IAC motor connector and connect the special tool (test harness: MD998463) in between.




2. Connect the analyzer special patterns pickup to the IAC motor-side connector terminal 1 (red clip of special tool), terminal 3 (blue clip), terminal 4 (black clip) and terminal 6 (yellow clip) respectively.

Alternate Method (Test harness not available)

1. Connect the analyzer special patterns pickup to ECM terminal 4, connection terminal 5, connection terminal 17 and connection terminal 18 respectively.




Observation conditions

STANDARD WAVE PATTERN




Wave Pattern Observation Points

Check that the standard wave pattern appears when the IAC motor is operating.




Point A: Presence or absence of induced electromotive force from the motor turning. (Refer to the abnormal wave pattern.)




Point B: Height of coil reverse electromotive force

EXAMPLES OF ABNORMAL WAVE PATTERNS




- Example 1

CAUSE OF PROBLEM
- Motor is malfunctioning. (Motor is not operating.)

WAVE PATTERN CHARACTERISTICS
- Induced electromotive force from the motor turning does not appear.




- Example 2

CAUSE OF PROBLEM
- Open circuit in the line between the IAC motor and the ECM.

WAVE PATTERN CHARACTERISTICS
- Current is not supplied to the motor coil on the open circuit side. (Voltage does not drop to 0 V.) Furthermore, the induced electromotive force waveform at the normal side is slightly different from the normal waveform.