Removing and installing anti-theft engine control unit J623 (Golf Plus) — VW

Removing and installing anti-theft
engine control unit
J623
(Golf Plus)
Special tools and workshop equipment required
Hot air blower from
wiring harness repair set
VAS 1978
Nozzle attachment from
wiring harness repair set
VAS 1978
If you wish to renew the engine control unit, connect the
vehicle diagnostic tester
and perform the guided function
“Renewing control unit”
.
Removing
Switch off ignition.
Remove plenum chamber bulkhead
General body repairs
Rep. gr.
50
Body - front; Plenum chamber bulkhead
.
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, connections and control units in the vicinity of the engine control unit to prevent damage through heat.
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.
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 possible injury.
Place nozzle of hot air blower close to shear-head bolt.
Switch on hot air blower and heat bolt for about 20 to 25 seconds.
Unscrew shear-head bolt using
mole grips
on bolt head.
The procedure for the second shear-head bolt is identical.
Then remove securing nuts for control unit bracket
arrows
.
Release connectors on engine control unit and pull off connector.
Press catches
1
and
2
outwards. Then pull engine control unit off control unit bracket in
direction of arrow
.
Installing
Push engine control unit onto control unit bracket until it engages in catches.
Fit connectors to engine control unit and lock in position.
Tighten securing bolts
arrows
to 10 Nm.
Install cover of protective housing.
Tighten new shear-head bolts
arrows
evenly until heads shear off.
Install plenum chamber bulkhead
General body repairs
Rep. gr.
50
Body - front; Plenum chamber bulkhead
.
If
engine control unit
J623
is renewed, erase learnt values and adapt engine control unit using
vehicle diagnostic tester
in
“Guided functions”
.
Read event memory, rectify any faults and then clear
Vehicle diagnosis tester
event memory,
“Guided Fault Finding”
.
Install plenum chamber bulkhead
General body repairs
Rep. gr.
50
Body - front; Plenum chamber bulkhead
.
The readiness code must be generated if the event memory has been cleared.
Carry out a road test.
Read control unit event memory again.