Tools required

WARNING: This page is about a different variant/trim than selected.

Heat gun - 1 - (from wiring harness repair kit VAS 1978)
Nozzle attachment - 2 - (also from wiring harness repair kit VAS 1978)

Fig 1: Heat Gun, Adapter Nozzle And Pliers

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Small, commercially available locking pliers (vise grips) - 3 -

CAUTION: By heating the threads, the retaining tabs, shear bolts and parts of the metal housing become very hot. Do not burn yourself on these parts! Make sure that only the threads are heated as much as possible, and not any of the surrounding parts. If necessary, cover these parts.

The threads of the shear bolts - 4 - (not screwed into the ECM) are coated with a locking compound. For this reason, the threads must be heated with the heat gun to remove both bolts.

Fig 2: Identifying Engine Control Module (ECM), Protective Housing, Retaining Tabs & Shear Bolts

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The threads of both shear bolts - 3 - , that are screwed into the ECM, are not coated with a locking compound. The threads in the ECM housing must not be heated (unintentional heating of the ECM).

Fig 3: Identifying Controls For Temperature Adjustment And Air Quantity

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Set adjustment on heat gun as shown in illustration, with temperature potentiometer - 2 - set to maximum heat and two-stage air flow switch - 3 - set to level 3.

Fig 4: Using Heat Gun To Direct Heat Gun Nozzle At Shear Bolt Of Retaining Tab

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Heat threads of connector-side shear bolts as shown in illustration for approx. 25 to 30 seconds.

Fig 5: Using Locking Pliers To Remove Shear Bolt

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Remove shear bolts with locking pliers (see direction of arrow).

NOTE:

Both shear bolts that are screwed into the ECM do not require heating to be removed. They can be removed without heat.

Disconnect metal retainers from ECM connectors.
Release and disconnect connector from Engine Control Module (ECM).
Connect test box V.A.G 1598/42 to wiring harness connector. Ground (GND) clip at test box must be clipped to battery Ground (-). Procedures will indicate whether ECM is to be connected to test box.
Perform test as described in relevant repair sequences.