Engine Control Module

Engine Control Module

Special tools, testers and auxiliary items required

• Wiring Harness Repair Kit (VAS 1978A)

• A small commercially available pliers

• Some engine control modules are not equipped with a protective housing. A protective housing is not installed in vehicles with automatic transmissions.

• The Engine Control Module (ECM) - 1 - is bolted to a protective housing - 5 -. To make removing the shear bolts - 4 - for the retaining tabs - 2 - more difficult, the threads are coated with locking compound.





• The protective housing must be removed to disconnect the connectors from the engine control module.

Removing

- If the engine control module is replaced, select "Guided Functions" on the Vehicle Diagnosis, Testing and Information System (VAS 5051B) and then "Replace engine control module".

- Turn the ignition and remove the ignition key.

- Pull the plenum chamber cover rubber seal in front of the nut - 1 - slightly.





- Disengage the wiring harness - 2 - at the mounts - A -.

- Remove nut - 1 -.

- Remove the filler neck - 3 - with the filler tube from the washer fluid reservoir and the opening in the body.

- Remove the bolts - arrows - and cover from the E-box.

- Release the retainers - arrows A - and remove the Engine Control Module (ECM) (J623) - arrow B -.





The engine control module - 1 - is secured in a metal housing - 5 - with retaining tabs - 2 - and shear bolts - 3 and 4 - to make it harder to access it.





• Some engine control modules are not equipped with a protective housing. A protective housing is not installed in vehicles with automatic transmissions.

The threads of the shear bolts - 4 - (that are 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.

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 and do not require to be heated (unintentional heating of the ECM).





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






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

Grinding and drilling is not permitted.

- Warm threads on connector-side shear bolts for approximately 25 to 30 seconds.





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





- The shear bolts installed in the engine control module do not need to be heated for removal.

- Disconnect metal retainers from the ECM connectors.

- Disengage the connectors from the engine control module and disconnect the connector.

- Remove old Engine Control Module (ECM) (J623) and install the Engine Control Module (ECM) (J623).

Installing

Install in reverse order of removal.

- After that, the Engine Control Module (ECM) (J623) must be equipped with the metal retainer.

- Clean threaded holes for shear bolts of locking compound residue. Cleaning can be performed with a thread cutter (tap).

- Always use new shear bolts.

• Tightening specification: Bolts for the E-box cover: 3.5 Nm

Perform the following step after installing a new engine control module:

- Activate the engine control module in the "Guided Functions" operating mode under "Replace engine control module" on the Vehicle Diagnosis, Testing and Information System (VAS 5051B).