Oscilloscope Patterns and Waveforms

MEASUREMENT METHOD
1. Disconnect the stepper motor connector, and connect the special tool (test harness: MD998463) 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 (blue clip), terminal 4 (black clip) and terminal 6 (yellow clip) respectively.

ALTERNATE METHOD (TEAT 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.





STANDARD WAVE PATTERN

Observation conditions

Function Special patterns

Pattern height High
Pattern selector Display
Engine condition When the engine coolant temperature is 20°C (68° F) or below, turn the ignition switch from OFF to ON (without starting the engine).
While the engine is idling, turn the A/C switch to ON.
Immediately after starting the warm engine (approx. 1 minute).

Wave pattern observation points
Check that the standard wave pattern appears when the stepper motor is operating.

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

Contrast with standard wave pattern Probable cause

Induced voltage does not appear or Motor is
is extremely small. malfunctioning

Point B: Height of coil reverse voltage

Contrast with standard wave pattern Probable cause

Coil reverse voltage does not Short in the coil
appear or is extremely small.





Examples of abnormal wave pattern

Cause of problem
Motor is malfunctioning. (Motor is not operating.)

Wave pattern characteristics
Induced voltage from the motor turning does not appear.