Oscilloscope Test

INJECTOR

Required Special Tools:
MB991348: Test Harness
MD998464: Test Harness

Measurement Method





1. Disconnect the injector intermediate connector, and connect the test harness special tool (MD998464) in between.
2. Connect the analyzer special patterns pickup to each injector intermediate connector terminal to analyze each cylinder:
- Terminal 2 (black clip of special tool) for the number 1 cylinder
- Terminal 3 (blue clip) for the number 3 cylinder
- Terminal 4 (white clip) for the number 5 cylinder

1. Disconnect the injector connector; and connect the test harness special tool (MB991348) in between. (All terminals should be connected.)
2. Connect the analyzer special patterns pickup to injector connector terminal 2.

Alternate method (Test harness not available)
1. Connect the analyzer special patterns pickup to PCM terminal 1. (When checking the number 1 cylinder)
2. Connect the analyzer special patterns pickup to PCM terminal 9. (When checking the number 2 cylinder.)
3. Connect the analyzer special patterns pickup to PCM terminal 24. (When checking the number 3 cylinder.)
4. Connect the analyzer special patterns pickup to PCM terminal 2. (When checking the number 4 cylinder.)
5. Connect the analyzer special patterns pickup to PCM terminal 10. (When checking the number 5 cylinder.)
6. Connect the analyzer special patterns pickup to PCM terminal 25. (When checking the number 6 cylinder.)

Standard Wave Pattern

Observation conditions

Standard wave pattern

Wave Pattern Observation Points

Point A: Height of injector coil induced voltage.

Point B: Injector drive time
1. The injector drive time should be synchronized with the scan tool tester display.
2. When the engine is suddenly rewed, the drive time will be greatly extended at first, but the drive time will soon return to original length.

IDLE AIR CONTROL MOTOR (STEPPER MOTOR)

Required Special Tool:
MB991709: Test Harness

Measurement Method

1. Disconnect the idle air control motor connector, and connect the test harness special tool (MB991709) in between. (All terminals should be connected.)
2. Connect the analyzer special patterns pickup to the idle air control motor connector terminal 1 terminal 3 terminal 4 and terminal 6 respectively.

Alternate method (Test harness not available)
1. Connect the analyzer special patterns pickup to PCM terminals 14, 15, 28 and 29.

Standard Wave Pattern

Observation conditions

Standard Wave Pattern

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

Point A:
Presence or absence of induced electromotive force from the motor turning. (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 the PCM.

- Wave pattern characteristics
Current is not supplied to the motor coil on the open circuit side. (Voltage does not drop to 0 volt.)
Furthermore, the induced electromotive force wave pattern at the normal side is slightly different from the normal wave pattern.

IGNITION COIL AND IGNITION POWER TRANSISTOR

Required Special Tool:
MB991348: Test Harness Set

Measurement Method

1. Disconnect the connector; and connect test harness special tool, (MB991348), in between. (All terminals should be connected.)
2. Connect the analyzer special patterns pickup to distributor connector terminal 3.

Alternate method (Test harness not available)
1. Connect the analyzer special patterns pickup to PCM terminal 11.

Standard Wave Pattern

Observation conditions

Standard Wave Pattern

Wave Pattern Observation Points

Point:
Condition of wave pattern build-up section and maximum voltage (Refer to abnormal wave pattern examples 1 and 2.

Examples of Abnormal Wave Patterns

Example 1 (Wave pattern during engine cranking)

- Cause of problem
Open-circuit in ignition primary circuit

- Wave pattern characteristics
Top-right part of the build-up section cannot be seen, and voltage value is approximately 2 volts too low.

Example 2 (Wave pattern during engine cranking

- Cause of problem
Malfunction in ignition power transistor

- Wave pattern characteristics
Power voltage results when the ignition power transistor is "ON"