Montero LS 4WD V6-2972cc 3.0L SOHC 12 Valve (1994)
Idle Air Control Motor (Stepper Motor): Oscilloscope Patterns and Waveforms
Wave Pattern Inspection Using an Analyzer
1. Disconnect the stepper motor connector, and connect the special tool (test harness: MB998463) in between.
2. Connect the analyzer special patterns pickup to the stepper motor-side connector terminal (1) (red clip on the special tool) , terminal (3) (green
clip) , terminal (4) (black clip) and terminal (6) (yellow clip) respectively.
ECM Connector Pin Numbers (from Wire Side)
Alternative method (when test harness is not available)
Connect the analyzer special patterns pickup to ECM terminals (58), (59), (67) and (68).
Observation Conditions
Scope Functions:
-
Pattern height: High
-
Pattern selector: Display
Test Condition 1: Turn the ignition switch from OFF to ON (without starting the engine)
Test Condition 2: While the engine is idling, turn the air conditioning switch to ON
Test Condition 3: Immediately after starting the warm engine (within 1 minute)
Standard Wave Pattern
Standard Wave Pattern
Wave pattern observation points:
Check that the standard wave pattern appears when the stepper motor is operating.
Abnormal Wave Pattern Carachteristics
Wave pattern observation points:
Point A: Presence or absence of induced voltage from the motor turning. (Refer to the abnormal wave pattern.)
In contrast with standard wave pattern the Induced Voltage does not appear or is extremely small. Probable cause: malfunction of motor
Point B: Height of coil back electromotive force
In contrast with standard wave pattern the Coil Back electromotive force does not appear or is extremely small. Probable cause: Short-circuit
in the motor coil
