Audi Workshop Service and Repair Manuals

Notes:

• ◆ Before connecting the test box, please note the comments on Page 24-27.
• ◆ The test box V.A.G 1598/31 is designed in such a way that it can be connected simultaneously to the engine control unit wiring harness and to the engine control unit itself.
• ◆ This has the advantage that the electronic motor control system remains fully functional when the test box is connected (for example, for measuring signals when the engine is running).
• ◆ Whether the engine control unit has to be additionally connected to the test box or not is described in the respective test procedures.
• ◆ Always use adapter set V.A.G 1594 A for connecting up measuring instruments (e.g. voltage tester V.A.G 1527 B, hand-held multimeter V.A.G 1526 A etc.)

Special tools and workshop equipment required

• ◆ V.A.G 1598/31

Procedure

• ‒ Switch ignition off.

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

• ‒ → Remove cover for electronics box (plenum chamber) -arrows-.

• ‒ → Carefully lever off the retainer bar with a screwdriver -arrow-.
• ‒ Release the connector latches and pull off the control unit connectors.

• ‒ → Connect V.A.G 1598/31 test box to connector on wiring harness. The earth clip on the test box is to be connected to the battery negative. Whether or not the engine control unit has to be additionally connected to the test box is described in the respective test procedures.
• ‒ Carry out test as described in the appropriate repair procedures.

Perform the following operations after re-connection of engine control unit:

• ‒ Interrogate fault memory and erase, if necessary .
• ‒ Perform adaption of throttle valve control part -J338 => Page 24-149.

Note:

In the first learning phase, during the basic setting operation for the engine, slightly irregular idling and slight jolting during driving are possible.

Comments on test box V.A.G 1598/31:

• ● In some Audi A4 vehicles, the control units and sleeve housing are without guides (see Figure 1).
• ● In these vehicles, it is impossible to use the V.A.G 1598/31 test box for electrical tests on the engine control unit or engine control harness.
• ● In these cases, contact the service department of the responsible marketing centre or importer because special test boxes are kept there for such cases.
• ● In the current series, the engine control units are now provided with guides on the connector housing (see Figure 2).

• ‒ → Figure 1; engine control units without guides; in this case, contact the service department of the responsible sales centre or importer.

• ‒ → Figure 2; engine control units with guides (see arrow); in this case, the V.A.G 1598/31 test box can be used as described in the manual.