SEAT Workshop Service and Repair Manuals

Engine control unit -J623- with locking device: removing and fitting When replacing the engine control unit To replace the engine control unit, connect the vehicle diagnostic tester and complete the guided function „Engine control unit: replace“. t  Removing → Anchor t  Installing → Anchor Check the tool and equipment equivalence table according to the applicability between Seat / VW / Audi / Skoda → Chapter Special tools and workshop equipment required

t  Pneumatic sabre saw -VAG 1523B- t  Hot air gun from cable repair set -VAS 1978A-, see equivalent → Anchor Removing –  Switch off ignition. –  Remove air cleaner housing → Chapter.

–  Open wiring guide -1- and lift locking device -2-. –  Take engine control unit out of retainer.

Using the body saw -VAG 1523B- make a groove on the heads of the shear screws for inserting a screwdriver.   Note t  The groove must be wide enough in order to be able to screw out the screws using an appropriate screwdriver. t  The thread on the shear screws can been treated with a threadlocker. For making sure that unscrewing is easier, you can warm the shear screws using the Hot air blower -VAS 1978/14A-. In doing so, take care that no bordering cables, plugs or components are damaged! .   WARNING The threads of the two shear screws which are screwed into the engine control unit are not secured with locking fluid. Do not apply heat to the threads in the control unit housing; this is not necessary and would cause overheating of the control unit. The threads of the shear screws which are not screwed into the engine control unit are not secured with locking fluid. To unscrew these bolts, the threads must therefore be heated with the hot-air blower. To ensure that damage (burning) is not caused to the cables and connectors as well as insulation and control units, the following steps must be observed in all cases: Remember the instructions for using the hot-air gun. Perform settings on hot air blower -4- as shown:

–  Turn temperature setting potentiometer -2- to maximum heat output (600 °C). –  Set two-stage switch for volume of air -3- to position 3.   Note t  Next, heat the breakaway bolts with the hot-air gun. This reduces the strength of the threadlocker on the thread of the breakaway bolts to make them easier to remove. t  Cover all painted parts to prevent damage from the hot-air gun or the self-locking pliers.   WARNING The threads of the two shear screws which are screwed into the engine control unit are not secured with locking fluid. Do not apply heat to the threads in the control unit housing; this is not necessary and would cause overheating of the control unit. When breakaway bolts are heated, some parts of the protective casing become very hot. Risk of burn injuries! Also, make sure that, as far as possible, you only heat the breakaway bolt and not adjoining parts. If necessary, cover these parts.   Note Next, heat the breakaway bolts with the hot-air gun. This reduces the strength of the threadlocker on the thread of the breakaway bolts to make them easier to remove.

–  Bring the nozzle of the hot-air gun up to the breakaway bolt on the lock. –  Connect hot air gun and heat the head bolt approx. 20 to 25 seconds.

–  Unscrew the shear screws using a screwdriver. –  Separate the protective casing from the engine control unit.

–  Disengage the plug connector of the the engine control unit and remove the engine control unit. Installing Installation is carried out in reverse order, noting the following: –  Clean threaded holes for shear bolts to remove any residue from locking fluid. The threads can be cleaned with a thread tap. –  Fit connectors and lock in position. –  Push protective housing over engine control unit. –  Install the protective casing from the engine control unit. –  Use new breakaway bolts. –  Tighten the shear screws evenly, until the screw heads break off.

–  Insert engine control unit into mounting bracket on bulkhead until it audibly engages in catches -2-. –  Insert wiring into wiring guide -1- and close guide. –  Install air cleaner housing → Chapter. When replacing the engine control unit –  Adjust the new engine control unit. –  Read fault memory, repair faults if necessary and then clear fault memory → Vehicle diagnostic, testing and information system VAS 5051„Guided fault finding“. –  If the fault memory has been erased, you must generate the readiness code again. –  Take vehicle for a test drive. –  Read control unit fault memory again.