Removing and installing engine control unit J623 with metal locking plate, Golf, Golf Estate, Golf SV — VW

Removing and installing
engine control unit
J623
with metal locking plate, Golf, Golf Estate, Golf SV
Special tools and workshop equipment required
Wiring harness repair set
VAS 1978 B
Hot air blower
VAS 1978/14A
1
with nozzle
2
from
wiring harness repair set
VAS 1978 B
Small grinder (commercially available)
Vehicle diagnostic tester
Removing
If engine control unit is renewed, select test sequence/function
Replace engine control unit
on
“vehicle diagnostic tester”
in
“Guided functions”
mode.
Switch off ignition and remove ignition key.
NOTICE
If the engine control unit comes into contact with the positive battery terminal, the engine control unit will be destroyed.
For this reason, the battery always needs to be disconnected prior to removing the engine control unit from its bracket.
Disconnect battery
Electrical system
Rep. gr.
27
Battery; Disconnecting and connecting battery
.
Release retaining clip
arrow
and take out
engine control unit
J623
.
Make groove (for a screwdriver) in head of shear bolt
1
using a small grinder
2
.
Note
The threads of the shear bolts are secured with locking fluid. To unscrew these bolts, the threads must therefore be heated with the hot air blower.
Set the hot air blower as shown in illustration. Meaning potentiometer for temperature regulation
2
set to maximum heating power and 2-stage switch for air volume
3
set to position 3.
CAUTION
Risk of burns from hot air blower. When heating up the thread of the locking element, the shear-head bolts and parts of the sheet-metal housing become hot as well.
Ensure to only heat up the thread and no surrounding components. Shield surrounding components with a sheet-metal plate if necessary.
Hold
hot air blower
VAS 1978/14A
with nozzle attachment
arrow
to thread of shear bolt and heat thread for about 20 to 30 seconds.
Unscrew shear bolt
1
using screwdriver
2
.
Detach metal locking plate from connectors for
engine control unit
J623
.
Release and unplug connectors.
Installing
Installation is carried out in the reverse order; note the following:
The metal locking plate must always be re-fitted on the
engine control unit
J623
.
Remove any locking compound residue from the threaded holes for the shear bolts. Threads can be cleaned using a thread tap.
Use new shear-head bolts.
After a new engine control unit has been installed, the following work procedure must be carried out:
Connect
vehicle diagnostic tester
.
Activate engine control unit with the function
“Replace engine control unit”
on vehicle diagnostic tester in
“Guided functions”
mode.