A. Engine 602.96

Electronic Diesel System Test (DE-04.12)

A. Engine 602.96

Test conditions:
- Coolant temperature 60°-80°C
- ACC system off
- Selector lever position "P"
- Fuse of overvoltage protection relay OK
- Battery voltage approx.12 Volts at overvoltage protection relay between terminals 1 and 5.
- Bowden cable connected tension free in lever.

Special Tools:

Equipment:

Location Of Components:

Functional Diagram Of Vacuum Line Routing:

Wiring Diagram:

On-off Ratio Test Connection:

Quick test with on-off ratio tester

Note: When performing this test, the air intake hose between the air flow sensor (B2/1) and the turbocharger must be connected, otherwise no signal will be sent to the EDS control unit (N39) for exhaust gas recirculation (EGR).

- Connect on-off ratio tester according to figure.
- Press button 100% IR.
- Run engine at 1200 rpm for at least 5 seconds.

To check instrument function, connect plug (a) for approx. 1 second to battery ground. Needle should go to 100% and return to 0%.

On-off ratio tester reading

Increase engine speed above 1200 rpm for at least 5 seconds.

No fault in system = Reading approx. 0%.

End of test

Fault in System = Reading approx. 100%.

- Trigger signal for system diagnosis: Connect plug (a) for approx. 1 second to battery ground. After plug (a) is removed from ground, the needle on the on-off ratio tester goes to 0% and starts to oscillate in regular intervals. Each oscillation must be counted. Afterwards, the needle will again go to the 100% reading.

Note: One oscillation = 0% - 100% - 0%.

The number of oscillations indicates which electrical component is faulty. See failure diagnosis table. Repeat test until no fault is indicated.