Audi Workshop Service and Repair Manuals

A - Electrical testing of injectors

• ‒ Remove connector from the injector which is to be tested.
• ‒ → Measure resistance between the valve contacts using V.A.G 1526.

• Specification: 13.5...15.5 Ohm

When the engine is at operating temperature, the resistance is increased by approx. 4...6 ω.

• ‒ If specification is not attained, replace injector .

B - Testing power supply

Test conditions

• ● Fuse for injectors OK

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

• ‒ Remove connector from the injector which is to be tested.
• ‒ → Connect diode test lamp V.A.G 1527 between contact 1 of the connector and engine earth.

• ‒ Switch on ignition, the diode test lamp should come on.
• ‒ If the diode test lamp does not light up, test for open circuits in the wiring between contact 1 and the fuse for the injectors - if necessary rectify open circuit.

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

• ‒ If the diode test lamp lights up, test activation of injectors.

C - Testing activation of injectors

• ‒ Remove connector from the injector which is to be tested.
• ‒ → Connect diode test lamp V.A.G 1527 between contact 2 of connector and battery positive (+).
• ‒ Operate starter for a few seconds (the engine can be allowed to start).

Specification: The diode test lamp should flash.

Note:

Diode test lamps with a low current draw continue to glow faintly between impulses from the engine control unit (rather than going out completely) and become much brighter when receiving an impulse.

If the diode test lamp does not flash:

• ‒ 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.
  => Page 24-23.
• ‒ → Test wiring between contact 2 of respective injector connector and engine control unit for continuity or short to positive.

• ‒ Rectify any open/short circuit as necessary.
• ‒ If the wiring is OK, replace engine control unit => Page 24-30.