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).

Special tools and workshop equipment required

• ◆ VAS 5051 and VAS 5051/1

•     1 -    Hotair 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)

Removing

• ‒ Connect the vehicle diagnostic, test and information system VAS 5051 and select the vehicle system "01 - Engine electronics". When doing this the ignition must be on.

→ The display on vehicle diagnostic, test and information system VAS 5051 will show the control unit identification and the coding -2-.

• ‒ Always start by calling up and printing out the control unit identification.
• ‒ 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 careful here, since control unit connectors are located in the immediate vicinity.

• ‒ Release catches and unplug control unit connectors.
• ‒ Remove windscreen wiper system

=> Electrical system; Repair group 92; Windscreen wiper system; Removing and installing windscreen wiper system

• ‒ Remove engine control unit with protective housing from bracket on body.

→ The locking plate -2- must only be unscrewed from mounting bracket after the whole unit is removed. The control unit can be only pulled out after the shear bolts -3- have been unscrewed from the locking plate!

• ‒ Clamp the control unit -1- in a vice -4-, as shown in illustration.

• ‒ → 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.
• ‒ 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.

The engine control unit can now be removed from the metal housing.

Installing

Installation is performed in the reverse sequence; the engine control unit is placed back into protective housing and new shear bolts are to be used.

• ‒ Bend back retainer on bracket.

Note:

After installing the new engine control unit the following operations must be performed:

• ‒ Interrogate and if necessary erase the fault memory => Page 01-7.
• ‒ Check the notes on coding new engine control units=>Page 01-83.

• ‒ On vehicles with cruise control (identifiable by controls on steering column), activate the cruise control via the engine control unit => Page 23-128.
• ‒ Perform adaption of immobilizer to engine control unit.

=> Electrical System; Repair Group 01; Self-diagnosis of electronic immobilizer; Adaptation procedure when engine control unit is replaced