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1.Check that the operation
sound of the stepper motor can be heard from the exhaust gas
recirculation 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 engine-ECU may
have failed.
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1.Remove the exhaust gas
recirculation valve.
2.Measure the resistance
between terminal No. 2 and either terminal No. 1 or terminal
No. 3 of the connector at the exhaust gas recirculation
valve.
Standard value: 20 - 24 Ω
(at 20°C)
3.Measure the resistance
between terminal No. 5 and either terminal No. 6 or terminal
No. 4 of the connector at the exhaust gas recirculation
valve.
Standard value: 20 - 24 Ω
(at 20°C)
4.If the voltage deviates
from the standard value, replace the exhaust gas
recirculation valve.
| note |
For removal and installation
of the exhaust gas recirculation valve (Refer to
 ).
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1.Remove the exhaust gas
recirculation valve (Refer to ).
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2.Attach a special tool test
harness (MB991658) to the connector at the exhaust gas
recirculation valve.
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3.
| caution |
Connecting battery voltage to
the exhaust gas recirculation valve for a long
term could damage the coil.
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Connect the positive (+) terminal of the
battery to terminal No. 2.
4.Connect terminals No.
1 and No. 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.
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5.
| caution |
Connecting battery voltage to
the exhaust gas recirculation valve for a long
term could damage the coil.
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Connect the positive (+) terminal of the
battery to terminal No. 5.
6.Connect terminals No.
4 and No. 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 a vibration can be felt during
the test, the stepper motor is normal.
8.Install
the exhaust gas recirculation valve (Refer to ).
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1.
| caution |
Do not use a solvent or
detergent, which could enter the motor and cause
it to malfunction.
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Remove the exhaust gas recirculation valve and check
that the exhaust gas recirculation valve is not stuck or
clogged with carbon deposits. Use a wire brush to clean the
valve if necessary.
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2.Install the exhaust gas
recirculation valve (Refer to ).
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