Audi Workshop Service and Repair Manuals

→ The engine control unit -1- is secured with a locking plate -2- and shear bolts -3- to a protective housing -4-.

The threads of the bolts are coated with a locking compound.

The engine control unit must be separated from the protective housing in order to detach the connectors from the control unit (for example, when connecting the test box or replacing the engine control unit).

Notes:

• ◆ Test box V.A.G 1598/31 is designed so that it can be connected to the wiring harness for the engine control unit and to the engine control unit itself at the same time.
• ◆ This has the advantage of enabling the engine management system to remain fully operational even with the test box connected (for example, when testing signals while the engine is running).
• ◆ 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.
• ◆ Always use adapter set V.A.G 1594A to connect test equipment (e.g. voltage tester V.A.G 1527B, hand-held multimeter V.A.G 1526A etc.).

Special tools and workshop equipment required

• ◆ V.A.G 1598/31

•     1 -    Hot air blower (in wiring harness repair set VAS 1978)
•     2 -    Shrink element for hot air blower ( in wiring harness repair set VAS 1978)
•     3 -    Vice grip wrench (commercial type)

Work sequence

• ‒ Switch off ignition.
• ‒ Lever off cover caps (2x) on wiper arms with a screwdriver.
• ‒ → Loosen hexagon nuts -arrows- several turns.
• ‒ Loosen wiper arms -1- by moving them around gently on the wiper shafts.
• ‒ Remove hexagon nuts completely and take off wiper arms.
• ‒ Remove rubber seal -2- from plenum chamber cover.
• ‒ Detach cover from plenum chamber -3- and move clear towards windscreen.

→ In order to avoid damaging wiring and connectors, you must fashion a shield -item 1 and 2- with sheet metal or similar. This is to prevent overheating of the connector housing and wiring harness.

• ‒ → Set controls on hot-air blower as shown in illustration:
  temperature control -2- to maximum heat and two-stage air delivery switch -3- to setting 3.

Note:

Thereafter, heat the screw base on locking plate, in which the shear bolts are located. This step reduces the locking effect of the compound on the shear bolt threading, which enables easier removal of the bolts.

• ‒ → Apply nozzle -1- of hot-air blower to bolt -2- on locking plate.

Note:

Be especially careful here, since control unit connectors are located in the immediate vicinity.

• ‒ Switch on the blower and apply heat to the thread for about 20 to 25 seconds.

• ‒ → Grip head of the shear bolts -2- with vice grip pliers -1- and turn anti-clockwise (direction of arrow). The pliers will have to be reapplied several times.

The procedure is the same for the second shear bolt.

Note:

Be especially care here, since engine control unit connectors are in the immediate vicinity.

• ‒ Release catches and unplug control unit connectors.

• ‒ → Connect test box V.A.G 1598/31 to wiring harness connectors. Also connect the earth clamp on the test box (not shown in the illustration) to vehicle 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 the repair instructions.

Note:

After reconnecting the engine control unit the following operations must be performed:

• ‒ Interrogate and if necessary erase the fault memory => Page 01-7.