Engine Control Module (ECM) (J623)

Engine Control Module, Replacing

Special tools, testers and auxiliary items required

• Heat gun.

• The Engine Control Module (ECM) (J623) - 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.





• To disconnect the electrical connectors from the Engine Control Module (ECM) (J623) (e.g. to connect the test box or to replace the ECM), the protective housing must be removed.

Removal

- Remove the right engine compartment trim - 3 -.





- Disengage gas-filled strut to remove engine compartment trim.

- Remove the four nuts on the Engine Control Module (ECM) (J623) retaining clips and tilt the clips to the side.

- Remove Engine Control Module (ECM) (J623) - 3 -.





The Engine Control Module (ECM) (J623) is secured with a retainer, shear bolts, and a protective housing to make it difficult to access the electrical harness connectors.





The threads of the shear bolts - 4 - not installed in ECM are coated with locking compound and must be heated with the heat gun to remove both bolts.

CAUTION!
After heating, parts are extremely hot. To prevent personal injury, avoid touching the protective housing after heating the shear bolts and surrounding area.

CAUTION!
The shear bolts that are screwed into the Engine Control Module (ECM) (J623), are not coated with a locking compound and do not require heating. Do not heat the Engine Control Module (ECM) (J623) or damage to the Engine Control Module (ECM) (J623) may occur.

To avoid damage (burning) of wire connections and harness connectors, insulation and control modules, the following work steps must be adhered to exactly! Observe operating instructions for heat gun.

- Using a Heat gun set at its lowest setting, heat the shear bolt for approx. 20 to 25 seconds.





- Remove the shear bolt with locking pliers. Discard the used shear bolts.





Repeat the previous steps for the second shear bolt.

- Remove the protective housing from the Motronic Engine Control Module (ECM) (J623).

• Adaptation values are erased when the connectors are disconnected from the Motronic Engine Control Module (ECM) (J623), DTC memory content remains intact.

- Disconnect the electrical harness connectors from the Motronic Engine Control Module (ECM) (J623).

Installing

Installation is in the reverse order of removal. Note the following:

- The ECM must be installed with the protective housing.

- Use new shear bolts.

- Remove a thread compound from the threaded holes with a thread cutter (tap) to allow for new shear bolt installation.

After installing a new Motronic Engine Control Module (ECM) (J623), the following work steps must be performed:

- Activate the Motronic Engine Control Module (ECM) (J623).