Air Bypass Valve: Testing and Inspection

Turbocharger Recirculating Valve N249, Checking

Special tools, testers and auxiliary items required

• Multimeter.

• Wiring diagram.

Test requirements

• Fuse (SB32) OK.

• The Motronic Engine Control Module (ECM) Power Supply Relay 2 (J670) OK.

• Battery voltage at least 12.5 volts.

• All electrical consumers such as, lights and rear window defroster, switched off.

• On vehicles with automatic transmission, selector lever in position " P" or "N".

• A/C switched off.

• Ground (GND) connections between engine/transmission/chassis OK.

• Ignition switched off.

• Voltage for the Turbocharger Recirculating Valve (N249) is supplied by the Motronic Engine Control Module (ECM) Power Supply Relay 2 (J670).

Test procedure

- Perform a preliminary check to verify the customers complaint. Refer to => [ Preliminary Check ] Preliminary Check.

Start diagnosis

- Remove the engine cover with air filter.

Checking internal resistance

- Disconnect the Turbocharger Recirculating Valve (N249) electrical harness connector- 2 -.





- Using a multimeter, check the Turbocharger Recirculating Valve (N249) terminals 1 to 2 for resistance.





Specified value: 10 to 20 ohms (at approx. 20° C)

If the specification was not obtained:

- Replace the Turbocharger Recirculating Valve (N249).

If the specification was obtained:

Checking Voltage supply

- Using a multimeter, check the Turbocharger Recirculating Valve (N249) electrical harness connector terminal 1 to Ground (GND).









- Operate the starter briefly.

Specified value: battery voltage.

- Switch the ignition off.

If the specified value was not obtained:

- Check the wiring from the Turbocharger Recirculating Valve (N249) electrical harness connector terminal 1 to the Motronic Engine Control Module (ECM) Power Supply Relay 2 (J670) socket 2/87 for a open circuit or a short circuit to Ground (GND).

- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

- If necessary, repair the wiring connection.

If no malfunctions are found in the wiring:

Checking wiring

If the manufacturers test box is being used. Perform the following step.

- Install the test box.

If the manufacturers test box is not being used. Perform the following step.

- Remove the Motronic Engine Control Module (ECM) (J623). Refer to => [ Motronic Engine Control Module J623, Replacing ] Motronic Engine Control Module J623, Replacing.

- Using a multimeter, check the Turbocharger Recirculating Valve (N249) electrical harness connector terminal 2 to Motronic Engine Control Module (ECM) (J623) electrical harness connector T60 terminal 21 for an open circuit.









Specified value: 1.5 ohms max.

If the specification is not obtained:

- Check the wiring for a short circuit to each other, Battery (+), and Ground (GND).

- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring and if the voltage supply was OK:

- Replace the Turbocharger Recirculating Valve (N249).

- Erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.

- Perform a road test to verify repair.

If the DTC does not return:

Repair complete, Generate readiness code. Refer to => [ Readiness Code ] Readiness Code.

- End diagnosis.

If the DTC does return and no malfunction is detected in the wiring and the voltage supply was OK:

- Replace the Motronic Engine Control Module (ECM) (J623). Refer to => [ Motronic Engine Control Module J623, Replacing ] Motronic Engine Control Module J623, Replacing.

- Assembly is performed in the reverse of the removal.

Final Procedures

After the repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Mode 03 - Read DTC Memory.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.

3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Readiness Code.

End of diagnosis.