Audi Workshop Service and Repair Manuals

Wiring and component check with adapter cable, 121-pin -V.A.G 1598/31- (test box)   Note

t  The adapter cable, 121-pin -V.A.G 1598/31- (test box) is designed for simultaneous connection to the wiring harness leading to the engine control unit and to the engine control unit itself. t  The advantage of this is that the electronic engine control system remains fully functional when the test box is connected (for example, for measuring signals when the engine is running). t  The relevant test procedure will state whether it is necessary to also connect the engine control unit to the test box. t  Always use auxiliary measuring set -V.A.G 1594 C- to connect test equipment (e.g. voltage tester -V.A.G 1527 B-, hand-held multimeter -V.A.G 1526C- etc.). –  Switch off ignition and remove ignition key. –  Detach rubber seal from plenum chamber cover in direction of -arrow-.

–  Detach plenum chamber cover -1- towards the front. –  Lever off both cover caps -3- with a screwdriver. –  Loosen hexagon nuts -4- several turns.

–  Loosen wiper arms -2- from wiper shafts by tilting slightly. –  Completely remove hexagon nuts and take off wiper arms.

–  Pull off retaining clips -1- and detach cowl panel grille -5-.

–  Remove cover of protective housing for control units -arrows-.

–  Carefully lever out retaining strap from engine control unit using a screwdriver -arrow-.

–  Release retaining tabs -arrows- and unplug connectors -1- and -2- from engine control unit. –  Remove engine control unit.   Caution To prevent damage to electronic components, select appropriate measuring range before connecting measuring leads and observe test requirements.

–  Connect adapter cable, 121-pin -V.A.G 1598/31- (test box) to wiring harness connector. Earth clip on test box must be connected to battery earth. The instructions for performing the individual tests indicate whether or not the engine control unit itself also needs to be connected to the test box. –  Carry out test as described in appropriate repair procedures. Perform the following after reconnecting engine control unit: –  Interrogate and, if necessary, erase fault memory → vehicle diagnostic, testing and information system VAS 5051.