Checking solenoid valve for boost pressure control -N75 — AUDI

AJL ANB APU
Special tools and workshop equipment required

V.A.G 1526 A
V.A.G 1527 B
V.A.G 1594 A
V.A.G 1598/22 (Engine codes AEB, AJL)
V.A.G 1598/31 (Engine codes ANB, APU)
VAS 5051 with VAS 5051/1

or

V.A.G 1551 with V.A.G 1551/3 A

Test requirements:

Connecting vehicle diagnostic, testing and information system VAS 5051 or fault reader V.A.G 1551.

Test sequence

Note:

The boost pressure control solenoid valve -N75 and the wiring connections are monitored by the engine control unit.

Read out fault memory of engine control unit.

If a fault relating to the boost pressure control solenoid valve -N75 is displayed:

Detach hoses from valve but leave the electrical connector plugged in.
Connect auxiliary hose to the valve connector marked with an arrow.
Initiate the final control diagnosis and actuate the solenoid valve for boost pressure control -N75.

Final control diagnosis
⇒
Solenoid valve for boost press. control -N75
Indicated on display:

The valve should click ...
... and should open and close (check by blowing into the auxiliary hose).

If the injector does not click:

Check internal resistance of valve.

If valve does not open or close properly:

Replace solenoid valve for boost pressure control -N75.

Checking internal resistance

Detach the connector from valve.
Connect multimeter to injector to measure resistance.
Specified value: 25 ... 35 ω

If specified value is not attained:

Replace solenoid valve for boost pressure control -N75.

If specified value is attained:

Check the power supply.

Checking power supply

Test requirements:

Fuse for solenoid valve for boost pressure control OK

=> Current Flow Diagrams, Electrical Fault-Finding and Fitting Locations

Fuel pump relay OK.

=> Motronic injection and ignition system (4 cylinder Turbo); Repair group 24; Servicing Motronic injection system; Checking fuel pump relay -J17 and actuation
Motronic injection and ignition system (4 cylinder Turbo)
Servicing Motronic injection system
Checking fuel pump relay -J17 and actuation

Connect voltage tester V.A.G 1527 B as follows:

Connector / Contact · Measure to
1 · Engine earth

Operate starter briefly.
The LED should light up.

If the LED does not light up:

Check the wiring from contact 1 on the connector via the fuse to the fuel pump relay for an open circuit:

=> Current Flow Diagrams, Electrical Fault-Finding and Fitting Locations

Rectify open circuit, if necessary

If the LED lights up:

Check actuation.

Checking actuation

Connect voltage tester V.A.G 1527 B to contacts 1 (positive) and 2 of the connector.
Initiate the final control diagnosis and actuate the solenoid valve for boost pressure control -N75.

Final control diagnosis
⇒
Solenoid valve for boost press. control -N75
Indicated on display:

The LED should flash.

If the LED lamp does not flash or if it lights up continuously:

Vehicles with engine code AEB, AJL:

Connect the V.A.G 1598/22 test box to wiring harness leading to engine control unit; the engine control unit should not be connected:

=> Motronic injection and ignition system (4 cylinder Turbo); Repair group 24; Servicing Motronic injection system; Wiring and component check with test box V.A.G 1598/22
Motronic injection and ignition system (4 cylinder Turbo)
Servicing Motronic injection system
Wiring and component check with test box V.A.G 1598/22

Check for open circuit and short to positive or earth in the following wiring connection:

Connector / Contact · Test box V.A.G 1598/22 / Socket
2 · 64

Vehicles with engine code ANB, APU:

Connect the V.A.G 1598/31 test box to wiring harness leading to engine control unit; the engine control unit should not be connected:

=> Motronic injection and ignition system (4 cylinder Turbo); Repair group 24; Servicing Motronic injection system; Wiring and component check with test box V.A.G 1598/31
Motronic injection and ignition system (4 cylinder Turbo)
Servicing Motronic injection system
Wiring and component check with test box V.A.G 1598/31

Check for open circuit and short to positive or earth in the following wiring connection:

Connector / Contact · Test box V.A.G 1598/31 / Socket
2 · 104

All models:

Rectify any open/short circuit as necessary.

If the wiring is OK:

Replace engine control unit.