Wastegate Bypass Regulator Valve -N75- Checking

Wastegate Bypass Regulator Valve N75, Checking

Special tools, testers and auxiliary items required
- Multimeter.
- Wiring diagram.

Test requirements







- The Motronic Engine Control Module (ECM) J220 fuses 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.

Procedure







- 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 is 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 Measure to
N75 electrical harness connector terminal
1 Engine Ground (GND)

- Operate the starter briefly.
Specified value: battery voltage.
- Switch the ignition off.

If the specification was not obtained:
- Check the wiring for a short circuit to Battery positive (+) or an open circuit.
- Check the electrical harness connector for damage, corrosion, lose or broken terminals.
- If necessary, repair the wiring connection.

If no malfunction is found in the 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) J220.







- Using a multimeter , check the Wastegate Bypass Regulator Valve N75 electrical harness connector terminal 2 to the Motronic Engine Control Module (ECM) J220 electrical harness connector 104 for an open circuit.

Wastegate Bypass Regulator Valve Motronic Engine Control Module
N75 electrical harness connector (ECM) J220 electrical connector test
terminal box socket
2 104

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, lose 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 Motronic Engine Control Module (ECM) J220.
- Install the engine cover with air filter.

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.

- End of diagnosis.





With Manufacturer's Scan Tool

Wastegate Bypass Regulator Valve N75, Checking







Special tools, testers and auxiliary items required
- Multimeter VAG1526A or equivalent
- Voltage tester VAG1527B
- Connector test set VAG1594A
- Adapter VAG1598/31
- Vehicle Diagnostic, Testing and Information System VAS5051 VAS5051 with VAS5051/1
or
- Scan Tool VAG1551 with VAG1551/3A

Requirement
- Vehicle Diagnostic, Testing and Information System VAS5051 or Scan Tool VAG1551 must be connected.

Work sequence

NOTE: The Wastegate bypass regulator valve N75 and its wiring are monitored by the engine control module.

- Read DTC memory of engine control module .

If display shows a DTC relating to Wastegate bypass regulator valve N75 :
- Disconnect hoses from valve; leave connector connected.







- Connect test hose to valve connection marked with - arrow - .
- Start Output Diagnostic Test Mode and actuate Wastegate bypass regulator valve N75 .

Indicated on display:
Output Diagnostic Test Mode -->
Wastegate bypass regulator valve -N75

- Valve must click...
- ...and must open and close (can be checked by blowing into test hose).

If valve does not click:
- Check internal resistance of valve.

If valve does not open or close properly:
- Replace Wastegate bypass regulator valve N75 .

Checking internal resistance
- Disconnect connector at valve.







- Connect multimeter and measure resistance at valve.
- Specification: 25 to 35 Ohms

If reading does not match specification:
- Replace Wastegate bypass regulator valve N75 .

If measured value matches specification:
- Check power supply.

Checking power supply

Requirements
- Fuse for wastegate bypass regulator valve OK
- Fuel pump relay OK







- Connect voltage tester VAG1527B as follows:

Connector contact Measure to
1 Engine Ground

- Briefly operate starter.
- LED must light up

If LED does not light up:
- Check for open circuit in wiring from contact 1 of connector through fuse to fuel pump relay
- If necessary, eliminate open circuit.

If LED lights up:
- Check actuation.

Checking actuation







- Connect voltage tester VAG1527B to contact 1 (positive) and 2 of connector.
- Start Output Diagnostic Test Mode and actuate Wastegate bypass regulator valve N75 .

Indicated on display:
Output Diagnostic Test Mode -->
Wastegate bypass regulator valve -N75-

- LED must flash

If LED does not flash or if it is permanently lit:
- Connect test box VAG1598/31 to engine control module wiring harness. Engine control module must not be connected.







- Check for open circuit and short to Ground/positive in following wiring connection:

Connector contact Test box VAG1598/31 socket
2 104

- If necessary, eliminate open circuit/short circuit.

If wiring is OK:
- Replace engine control module.