Operation CHARM: Car repair manuals for everyone.

Exhaust Gas Recirculation: Testing and Inspection

EGR VALVE (STEPPER MOTOR) CHECK

Required Special Tool:
MB991658: Test Harness Set

Checking the Operation Sound
1. Check that the operation sound of the stepper motor can be heard from the EGR valve when the ignition switch is turned ON (without starting the engine).
2. If the operation sound cannot be heard, inspect the drive circuit of the stepper motor.

NOTE: If the operation sound is not heard, and the circuit is normal, either the stepper motor or the PCM may have failed.

Checking the Coil Resistance




1. Remove the EGR valve.
2. Measure the resistance between terminal No.2 and either terminal No. 1 or terminal No.3 of the connector at the EGR valve.

Standard value: 20 - 24 ohms [at 20 °C (68 °F)]

3. If the resistance is not within the standard, replace the EGR valve.
4. Measure the resistance between terminal No. 5 and either terminal No. 6 or terminal No. 4 of the connector at the EGR valve.

Standard value: 20 - 24 ohms [at 20 °C (68 °F)]

5. If the resistance is not within the standard, replace the EGR valve.

Operation Check

1. Remove the EGR valve.




2. Connect special tool MB991658 to the EGR valve.




3. Connect the positive (+) terminal the battery to terminal No. 2.

CAUTION: Connecting battery voltage to the EGR valve for a long term could damage the coil.

4. Connect terminals 1 and 3 to the negative (-) terminal of the battery, in order to test whether the stepper motor vibrates (with a slight shudder), indicating that the stepper motor is operating.
5. Connect the positive (+) terminal the battery to terminal No. 5.

CAUTION: Connecting battery voltage to the EGR valve for a long term could damage the coil.

6. Connect terminals 4 and 6 to the negative (-) terminal of the battery, in order to test whether the stepper motor vibrates (with a slight shudder), indicating that the stepper motor is operating.
7. If vibrations can be felt as a result of the test, the stepper motor is determined to be normal.