Audi Workshop Service and Repair Manuals

Renewing engine control unit -J623- Special tools and workshop equipment required

t  Hot air blower -1- (from the wiring harness repair set -VAS 1978A-) t  Nozzle attachment -2- (also from wiring harness repair set -VAS 1978A-) t  Commercially available vice grip pliers (mole grip) -3- t  Vehicle diagnostic, testing and information system -VAS 5051B-

The engine control unit -1- is bolted to the locking plates -2 and 5-. To make it more difficult to unscrew the shear bolts -4- for locking plate -2-, their threads have been coated with locking fluid. The protective housing has to be removed before the connectors can be unplugged from the engine control unit (e.g. to connect the test box or renew the engine control unit). To make it more difficult to unscrew the shear bolts, their threads have been coated with locking fluid. Removing –  When renewing engine control unit, select diagnosis object “Replace engine control unit” in “Guided Functions” on vehicle diagnostic, testing and information system -VAS 5051B-. –  Switch off ignition and remove ignition key. –  Lever off caps on windscreen wiper arms with a screwdriver.

–  Loosen hexagon nuts -arrows- several turns. –  Loosen wiper arms from wiper shafts by tilting slightly. –  Completely remove hexagon nuts and detach wiper arms from wiper shafts.   Note Use puller (commercially available) to remove wiper arms if necessary.

–  Unclip washer jets -arrow-. –  Push washer jets through assembly opening back into plenum chamber, leaving water hoses connected.

–  Pull off rubber seal -1- from plenum chamber cover -2-. –  Detach plenum chamber cover -2-. The following steps are only required up to and including model year 2006. Run wiper shafts to service position. –  First close bonnet. –  Switch ignition on and then off again. Within 10 seconds, press wiper switch down once to brief wipe position.   Note The wiper shafts will now run to the service position. –  Then open bonnet again. All models: –  Remove ignition key. Procedure:   WARNING The following procedure must be followed exactly to prevent any damage (scorching) to wiring, connectors, insulation and control units. Observe operating instructions for hot air blower.

–  Select settings on hot air blower as shown in illustration, i.e. set temperature potentiometer -2- to maximum heat output and two-stage air flow switch -3- to position 3.   Note t  Then use hot air blower to heat shear bolts. This step reduces inhibiting action of locking fluid on shear bolt threads and makes it easier to unscrew these bolts. t  Cover up all painted parts to avoid any damage caused by hot air blower or vice-grip pliers.   WARNING Parts of the protective housing will become very hot as a result of heating the shear bolts. Take care to avoid burns. Try to ensure that only the shear bolt is heated and none of the nearby components. These should be covered if necessary. –  Place the hot air blower nozzle close to the shear bolt on the protective housing. –  Switch on the hot air blower and heat the bolt for approximately 20 to 25 seconds. –  Then grasp the bolt head with the vice-grip pliers and unscrew the shear bolt. The procedure for the second shear bolt is exactly the same. Engine control unit can now be separated from protective housing.

Bracket for engine control unit: version 1 –  Release clip “arrow” and remove engine control unit.

Bracket for engine control unit: version 2 –  Release front connector on engine control unit and unplug connector. –  Pull engine control unit out of retainer -arrow- (wiper shafts in service position). –  Release rear connector on engine control unit and unplug connector. Installing engine control unit Installation is performed in the reverse sequence. –  After installation, the locking plate must be re-fitted on the engine control unit -J623-. –  Clean threaded holes for shear bolts to remove any residue from locking fluid. This can be done using a thread tap. –  Use new shear bolts. The following steps are only required up to and including model year 2006. –  Return wiper arms to normal position. –  First close bonnet. –  Switch on ignition and press wiper switch down once to brief wipe position. The wipers will then return to the normal position. –  Activate engine control unit via vehicle diagnostic, testing and information system -VAS 5051B- in “Guided Functions” mode, “Replace engine control unit”.