Wastegate Bypass Regulator Valve N75, Checking

Wastegate Bypass Regulator Valve N75, 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.

NOTE: 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. Preliminary Check

Start diagnosis
- Remove the engine cover with air filter.

Checking internal resistance







- Disconnect the Wastegate Bypass Regulator Valve N75 electrical harness connector - 1 -.







- Using a multimeter, check the Wastegate Bypass Regulator Valve N75 terminals 1 to 2 for resistance.

Specified value: 20 to 30 Ohms (at approx. 20 degrees C)

If the specification was not obtained:
- Replace the Wastegate Bypass Regulator Valve N75.

If the specification was obtained:

Checking Voltage supply







- Using a multimeter, check the Wastegate Bypass Regulator Valve N75 electrical harness connector terminal 1 to Ground (GND).

Wastegate Bypass Regulator Valve N75 Measure to
electrical harness connector terminal
1 Engine 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 Wastegate Bypass Regulator Valve N75 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.







- Using a multimeter, check the Wastegate Bypass Regulator Valve N75 electrical harness connector terminal 2 to Motronic Engine Control Module (ECM) J623 electrical harness connector T60 terminal 4 for an open circuit.

Wastegate Bypass Regulator Motronic Engine Control Module
Valve N75 electrical harness (ECM) J623 electrical harness connector
connector terminal T60 terminal or test box socket
2 4

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 Wastegate Bypass Regulator Valve N75.
- Erase the 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. Monitors, Trips, Drive Cycles and Readiness Codes
- 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.
- 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. Diagnostic Mode 03 - Read DTC Memory
2. If necessary, erase the DTC memory. Diagnostic Mode 04 - Erase DTC Memory
3. If the DTC memory was erased, generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

End of diagnosis