Audi Workshop Service and Repair Manuals

A - Electrical testing of injectors

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

Specification: approx. 14.5 ω.

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

• ‒ If the measured value is not as specified, renew the injector.

B - Testing power supply

Test conditions

• ● Fuel pump relay OK, testing .
• ● Fuse for injectors OK.

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

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

• ‒ Operate starter for a few seconds (the engine can be allowed to start). The diode test lamp should light up.
• ‒ 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 plug connector from the injector which is to be tested.
• ‒ → Connect diode test lamp V.A.G 1527 between the battery positive terminal (+) and contact 2 on the connector.
• ‒ 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 test box V.A.G 1598/22 to wiring harness for engine control unit .
• ‒ → Test for open circuit or short to positive in the wiring between the engine control unit and contact 2 on the plug connector for the injector being tested.

• ‒ Rectify short circuit or open circuit if necessary.
• ‒ If the wiring is OK, fit a new engine control unit .