Volkswagen Workshop Service and Repair Manuals

Test conditions

• ● Fuse 18 OK.

Checking function

Engine codes ADX, AEA:

Functional check can be performed via final control diagnosis .

• ‒ Remove air cleaner cover.
• ‒ → Start engine and run at idling speed, or if engine will not start, operate starter. The spray formation must be visible on the
       throttle valve.
• ‒ Switch off ignition and check injector (N181) for leaks.
       Leakage must not exceed 2 drops per minute.

If no spray can be seen:

• ‒ Check fuel pressure regulator => Page 24-72 .
• ‒ Check activation.

Checking activation

Special tools, testers and auxiliary items

• ◆ Test box V.A.G 1598/18
• ◆ Diode test lamp V.A.G 1527
• ◆ Adapter set V.A.G 1594
• ◆ Current flow diagram

Test sequence

• ‒ Remove air cleaner.
• ‒ → Pull 4 pin connector -1- off injection unit -2-.
• ‒ Connect diode test lamp V.A.G 1527 with aux. cables from V.A.G 1594 to contacts 3+4 on connector -1-.
• ‒ Operate starter and check injector voltage supply.
       LED must flicker

LED flickers:

• ‒ Switch off ignition
• ‒ Renew injector.

If the LED does not flicker:

• ‒ Switch off ignition

• ‒ → Connect test box V.A.G 1598/18 to control unit wiring loom.
• ‒ Check wire between 4 pin connector contact 3 and test box socket 7 for open circuit according to current flow diagram (from the central connector to control unit = resistance wire).
       Wire resistance: Max. 3.5 ω
• ‒ Check wire between 4 pin connector contact 4 and relay plate for open circuit according to current flow diagram (from the central connector to relay plate = resistance wire).
       Wire resistance: Max. 2.5 ω
• ‒ Additionally check wires for short to one another.
       Specification: ∞ω

If no wiring fault is detected:

• ‒ Renew Mono Motronic control unit (J257)
  , item 10 .

Checking injector resistance

• ‒ → Pull plug -1- off connector -2-.
• ‒ Check injector resistance with multimeter and aux. cables from V.A.G 1594 on contacts 3+4 of connector -2-:
       Specification: 1.2...1.6 ω
       (at an ambient temperature of +15...30 °C)