VW Golf manuals

Volkswagen Golf Service & Repair Manual: Removing and installing engine control unit -J623- (with metal locking plate)

Special tools and workshop equipment required
   
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.
  Note
If the engine control unit comes into contact with the positive battery terminal, the engine control unit will be destroyed.
Therefore, the battery must be disconnected before the engine control unit is removed → Electrical system; Rep. gr.27.
 

Removing and installing engine control unit -J623- (with metal locking plate)

–  Release retaining clip -arrow- and take out engine control unit -J623-.
  Note
Cover the area around the engine control unit, and protect it from flying sparks.
 

Removing and installing engine control unit -J623- (with metal locking plate)

–  Make groove (for a screwdriver) in head of shear bolt -1- using a small grinder -2-.
  Note
 

Removing and installing engine control unit -J623- (with metal locking plate)

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.
–  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.
Risk of damage to adjacent components caused by hot air blower. Risk of overheating.If necessary, cover adjacent components.
 

Removing and installing engine control unit -J623- (with metal locking plate)

–  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.
 

Removing and installing engine control unit -J623- (with metal locking plate)

–  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 residues from the threaded holes for the shear-head bolts. Threads can be cleaned using a tap (thread cutter).
–  Use new shear-head bolts.
After having installed the new engine control unit, the following work must be carried out:
–  Connect battery → Electrical system; Rep. gr.27.
–  Connect vehicle diagnostic tester.
–  Switch on ignition and select the following menu options on vehicle diagnostic tester:
01 - Engine electronics
Guided Functions
01 - Renew engine control unit
 

Removing and installing engine control unit -J623- (with metal locking plate)

Engine control unit
...

Removing and installing engine control unit -J623- (with protective housing)
Special tools and workshop equipment required     Hot air blower -VAS 1978/14A--item 1- with nozzle - ...

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