Air Bypass Valve: Testing and Inspection

Wastegate Bypass Regulator Valve, Checking

Function
- With power off, the long connector is closed.
- Both short connectors are inter-connected.
- When triggered, the connection between the long and both short connectors is opened.

Check for leaks
- Remove wastegate bypass regulator valve.
- Re-connect removed wastegate bypass regulator valve to wiring harness.
- Start output Diagnostic Test Mode (DTM) and advance through test program to select wastegate bypass regulator valve -N75-. Refer to "Scan Tool Testing/Output Diagnostic Test Mode (DTM) (Function 03)" Testing and Inspection
- Blow into long connector during DTM to check whether valve opens properly.

If necessary:
- Replace wastegate bypass regulator valve -N75-.

Checking wastegate bypass regulator valve -N75-
- Disconnect harness connector from valve - N75-.








- Connect multimeter US 1119 (Fluke 83 or equivalent) to check resistance between terminals of valve -N75-.
Specified value: 25-35 Ohms

If resistance is not OK:
- Replace valve.

Check voltage supply for wastegate bypass regulator valve -N75-


NOTE: Voltage supply for the waste gate bypass regulator valve is provided by the fuel pump relay.


- Fuse for -N75- OK
- Disconnect harness connector from valve.







- Connect VAG 1527B LED test light between harness connector terminal 1 and engine Ground.
- Operate starter motor.
LED test light must light up

If LED does not light:
- Check wiring for open circuit between terminal 1 to and fuse, according to wiring diagram. Repair if necessary.

If wiring is OK:
- Check fuel pump relay. Testing and Inspection

Signal for wastegate bypass regulator valve, checking
- Disconnect harness connector for valve - N75.







- Connect VAG 1527B LED voltage tester between connector terminals 1 (B+) and 2.
- Start output Diagnostic Test Mode (DTM) and advance through test program to select wastegate bypass regulator valve -N75-. Refer to "Scan Tool Testing/Output Diagnostic Test Mode (DTM) (Function 03)" Testing and Inspection
LED test light must blink

If LED test light does not blink, or stays on continuously:
- Connect VAG 1598/22 test box to ECM harness connector. Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAG 1598/22 Test Box" Testing and Inspection







- Check wiring for open circuit or short circuit to B+ between connector terminal 2 and ECM/test box socket 64. Repair if necessary.

If wiring is OK:
- Replace Motronic ECM -J220-.
- Carry out adaptation of throttle valve control module to ECM.
- Check readiness code. If Diagnostic Trouble Code (DTC) memory has been erased, or ECM was disconnected, generate new readiness code.
Refer to "Monitors, Trips and/or Drive Cycle/Displaying Readiness Code" Testing and Inspection
Refer to "Monitors, Trips and/or Drive Cycle/Generating Readiness Code" Testing and Inspection