EGR Valve (Stepper Motor) Check
EGR VALVE (STEPPER MOTOR) CHECKRequired 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 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.
4. Connect terminal No. 1 or terminal No. 3 to the negative (-) terminal of the battery to test the presence of vibrations that result from the operation of the stepper motor.
5. Connect the positive (+) terminal the battery to terminal No. 5.
6. Connect terminal No. 4 or terminal No. 6 to the negative (-) terminal of the battery to test the presence of vibrations that result from the operation of the stepper motor.
7. If vibrations can be felt as a result of the test, the stepper motor is determined to be normal.
EGR VALVE (STEPPER MOTOR) CLEANING
NOTE: DO not use solvents or other cleaning agents, which will enter the motor and cause a malfunction.
Remove the EGR valve and make sure that it is not stuck and does not have any carbon deposits. If there are any carbon deposits, use a wire brush to clean it.