Audi Workshop Service and Repair Manuals

• ‒ → Screw out bolts -arrows-.
• ‒ Remove air duct -1- and -2-.

Checking internal resistance

• ‒ Switch off ignition.
• ‒ → Unplug connector -arrows- from charge pressure control solenoid valve.

• ‒ → Connect multimeter to valve for resistance measurement.
• ‒ Specification: 14 ... 20 ω

If reading does not match specification:

• ‒ Replace charge pressure control solenoid valve -N75.

Checking power supply

• ‒ → Connect multimeter to measure voltage between contact 2 and earth.
• ‒ Switch on ignition.
• ‒ Specification: Approx. battery voltage

If reading does not match specification:

• ‒ Check for open circuit in wiring and repair if necessary.

Checking actuation

Test requirement:

• ● Vehicle diagnostic, testing and information system VAS 5051 connected; vehicle self-diagnosis and vehicle system "01 - Engine electronics" selected

• ‒ → Connect up voltage tester V.A.G 1527 B between contacts 1 and 2.

→ Readout on VAS 5051:

• ‒ Enter diagnostic function "03 - Final control diagnosis" in selection -1-.

• ‒ Actuate charge pressure control solenoid valve -N75.

→ Readout on VAS 5051:

•     A -    3. control element being tested
•     3 -    Charge pressure control solenoid valve-N75
• ‒ LED must flash slowly

Note:

Voltage testers with a low current input do not go out completely between actuation of engine control unit, but rather continue to glow slightly and become distinctly brighter on actuation.

• ‒ Terminate function "03 - Final control diagnosis" by touching ◂ key.

→ Readout on VAS 5051:

• ‒ Enter diagnostic function "06 - End output" in selection -1-.

If LED does not respond as described:

• ‒ → Remove rubber seal from plenum chamber cover in direction of arrow.
• ‒ Remove plenum chamber cover -1- from the front.

• ‒ → Remove electronics box cover in plenum chamber -arrows-.

• ‒ → Carefully lever off retainer bar with screwdriver -arrow-.

• ‒ → Release connector lock -arrow- and unplug connectors -1- and -2- from control unit.

• ‒ → Connect test box V.A.G 1598/31 to cable harness connector. Actual engine control unit is not to be connected. Clip test box earthing clip onto chassis (not shown in diagram).

• ‒ → Check for open circuit and short to earth/positive in the following wiring.

• ‒ If necessary, eliminate open circuit in wiring/short circuit.