Removing and installing diesel direct injection system control unit J248 — AUDI

Removing and installing
diesel direct injection system control unit
J248
Note
The engine control unit is bolted to its protective housing. To make it more difficult to unscrew the shear bolts
arrows
, their threads have additionally 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).
Special tools and workshop equipment required
Hot air blower
VAS 1978/14A
item 1
with nozzle attachment
2
from
wiring harness repair set
VAS 1978 B
Vice-grip pliers
3
(commercially available)
Removing
When renewing engine control unit, select diagnosis object
“Renew engine control unit”
in
“Guided Fault Finding”
Vehicle diagnostic tester
.
Switch off ignition.
Lever off caps on windscreen wiper arms with a screwdriver.
Loosen hexagon nuts
arrows
several turns.
Loosen wiper arms from wiper shafts by tilting them slightly.
Completely remove hexagon nuts and detach wiper arms from wiper shafts.
Unclip washer jets
arrow
.
Push washer jets through assembly opening back into plenum chamber, leaving hoses connected.
Pull rubber seal
1
off plenum chamber cover.
Detach plenum chamber cover
2
.
Run wiper arms 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 arms will now run onto the main part of the windscreen (service position).
Remove ignition key.
Then open bonnet again.
To make it more difficult to unscrew the shear bolts, their threads have been coated with locking fluid.
Engine control unit must be separated from protective housing before connectors can be unplugged from engine control unit (e.g. when connecting test box or replacing engine control unit). This procedure is described in the following.
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
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.
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.
Release front connector
1
from engine control unit and unplug connector.
Pull engine control unit out of retainer
arrow
(wiper arms in service position).
Release rear connector on engine control unit and unplug connector.
Installing
Installation is performed in the reverse sequence.
Make sure you fit protective housing back on engine control unit.
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.
With bonnet closed, move windscreen wiper motor back to normal park position (switch ignition on and off again briefly).
Within 10 seconds, press wiper switch down once to
“brief wipe”
position.
The wiper motor will run back to the normal park position.
Install windscreen wiper arms
Rep. gr.
92
.
After installing a new engine control unit, the following operations must be performed:
Activate engine control unit in
“Guided Fault Finding”
under diagnosis option
“Replace engine control unit”
Vehicle diagnostic tester
.