EGR - Vacuum Transducer Leak Test

Date: August 1999

Order No.: P-SI-MBUSA-14.20/13

Supersedes:

Group: 14

SUBJECT:
ALL DIESEL MODELS
EGR VACUUM TRANSDUCER LEAK TEST

Following are procedures for an EGR vacuum transducer in-car characteristic curve test, internal leak test, and external leak test.

In-car characteristic curve test

The Mercedes-Benz Special Tool vacuum gauge (see below) is used to monitor the vacuum signal of the EGR vacuum transducer while operational in the vehicle. The leak test is performed at 25%, 50%, and 75% duty cycle (DC) using the Hand-Held Tester (HHT). Duty cycle is activated by way of the HHT 'activation' menu (the second screen of # 3 "EGR valve").

1. Check the vacuum pump for proper output. See appropriate diagnostic material for specifications.

2. Make sure the vacuum gauge needle reads "0".

3. Connect the vacuum gauge hose to the EGR vacuum transducer OUT cover port.

4. With the engine idling, activate the duty cycle using the HHT and observe the vacuum gauge readings.

5. The vacuum gauge should read steady, with no oscillation, within the below applicable tolerance ranges.

6. The vacuum reading should drop to its nominal value again once disconnecting the HHT.

7. If the vacuum reading is not within its applicable tolerance range, replace the vacuum transducer.

Tolerance Ranges:

Note:
The HHT can only access the duty cycle of the EGR vacuum transducer. To test the pressure flap/waste gate transducer, the electrical plug must be disconnected from the vacuum transducer and connected to the pressure flap/waste gate transducer. Make sure the electrical plug is connected back to its original position upon completion and all DTC's are erased after the test.

Internal leak test

1. Connect the vacuum gauge hose to the EGR vacuum transducer ATM cover port.

2. Leave the VAC and OUT cover ports open.

3. Pump up the vacuum until the gauge reads approximately 450 mbar (13").

4. If the vacuum gauge reading drops from 450 mbar to 400 mbar in less than 2 seconds, replace the EGR vacuum transducer.

External leak test

1. Cap-off the OUT and ATM cover ports.

2. Connect the vacuum gauge hose to the VAC cover port.

3. Pump up the vacuum until the gauge reads approximately 600 mbar (18").

4. If the vacuum gauge reading drops from 600 mbar to 500 mbar in less than 15 seconds, replace the EGR vacuum transducer.

In Case of Warranty

Operation: Replace EGR vacuum transducer

Damage Code Operation Number Time (hrs.) Model Indicator(s)

14398 04 14 8012 0.4 *

* see Microfiche for applicable model

Parts Information

Part Name Part Number

EGR vacuum transducer A 000 545 03 27
EGR vacuum transducer A 000 545 04 27

Special Tools (Vacuum Gauge):

Special Tools