Analyzer Test

IDLE AIR CONTROL MOTOR (STEPPER MOTOR)

Measurement Method
1. Disconnect the idle air control motor connector, and connect the special tool (test harness: MB998463) in between.




2. Connect the analyzer special patterns pickup to the idle air control motor connector terminal 1 (red clip of the special tool), terminal 3 (green 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 PCM terminals 14, 15, 28, and 29.(signal wave pattern.)

Standard Wave Pattern:

Standard Wave Pattern

Wave Pattern Observation Points
Check that the standard wave pattern appears when the idle air control motor is operating.




Point A: Condition of wave pattern build-up section and maximum voltage (Refer to abnormal wave pattern.)




Point B: Height of coil back electromotive force.

Examples of Abnormal Wave Patterns




- Example 1

CAUSE OF PROBLEM
Malfunction of motor (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 idle air control motor and PCM.

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 wave pattern at the normal side is slightly different from the normal wave pattern.