Removing and installing engine control unit J623 with protective housing — VW

Removing and installing
engine control unit
J623
with protective housing
Special tools and workshop equipment required
Electric cutter
V.A.G 1561A
Saw set
V.A.G 1561/14
Hot air blower from
wiring harness repair set
VAS 1978 B
Nozzle attachment from
wiring harness repair set
VAS 1978
Grip pliers
Note
If the engine control unit is to be renewed, connect
vehicle diagnosis, testing and information system
VAS 5051
and carry out function
“Renew control unit”
.
Removing
Switch off ignition.
Remove wiper arms and plenum chamber cover.
Remove plenum chamber bulkhead
General body repairs, exterior
Rep. gr.
50
Plenum chamber bulkhead; Removing and installing plenum chamber cover
.
Note
The shear-head bolt threads are coated with locking compound. Heating the shear-head bolt with a hot air blower releases the locking effect of the locking compound.
Caution
Cover lines, cables, connections and control units in the vicinity of the engine control unit to prevent damage through heat.
Set hot air blower
4
as shown in illustration:
Turn potentiometer for temperature adjustment
2
to maximum heater output (600°C).
Set two-stage switch for air flow rate
3
to position 3.
WARNING
When shear-head bolts are heated up, parts of the protective housing will be subjected to a large amount of heat. Wear protective gloves to avoid injury.
Move nozzle of hot air blower towards a shear-head bolt.
Switch on hot air blower, and heat bolt for approx. 20 to 25 seconds.
Unscrew shear-head bolt using
grip pliers
on bolt head.
The procedure for the second shear-head bolt is identical.
Note
If the bolts cannot be unscrewed, saw into the heads of the shear-head bolt so that 2 parallel slots are created
arrows
. Then, unscrew bolts.
Insert a screwdriver
A
between protective housing and retaining plate
arrow
.
Using screwdriver
A
, lever protective housing upwards, and pull it sideways off retaining plate
arrow
.
Release and detach front connector
1
from engine control unit.
Lever up catch
2
slightly.
Then push engine control unit out of retainer
arrow
.
Release and detach rear connector from engine control unit.
Installing
Connect and lock rear connector to engine control unit.
Push engine control unit onto retaining plate.
Push locking mechanism
2
towards engine control unit.
Connect and lock front connector
1
to engine control unit.
Push protective housing onto retaining plate.
Evenly tighten shear-head bolts
1
until bolt heads shear off.
Install plenum chamber bulkhead
General body repairs, exterior
Rep. gr.
50
Plenum chamber bulkhead; Removing and installing plenum chamber cover
.
Install wiper arms and plenum chamber cover.
Reading and erasing engine control unit fault memory
Special tools and workshop equipment required
Vehicle diagnostic tester
Connect
vehicle diagnostic tester
as follows:
Connect diagnosis cable connector
2
to diagnostic connection in driver footwell.
Start engine and run at idling speed.
Only if engine does not start:
Switch ignition on.
Selecting operating mode:
Press button for
“Vehicle self-diagnosis”
on display.
Selecting vehicle system:
Press button
“01 - Engine electronics”
on display.
The control unit identification with code
2
as well as the vehicle identification number and immobiliser identification number will be indicated in the centre section of the display.
Note
A print-out can be made if required. To do this, press the
“Print”
button.
Selecting diagnostic function:
Press
“02 - Read fault memory”
button on the display.
If no fault is stored in engine control unit,
“0 fault detected”
is displayed.
If faults are stored in the engine control unit, these are listed on the display.
Press
←
button.
Press
“05 - Delete fault memory”
button on the display.
Press
“06 - End output”
function.
Note
If the fault memory was cleared, the readiness code must be generated
vehicle diagnostic tester
“Guided functions”
.