Engine Control Module: Service and Repair

Engine Control Module

Special tools, testers and auxiliary items required

• Heat Gun 220 V/50 Hz (VAS 1978/14A) with Nozzle Attachment from the Wiring Harness Repair Kit (VAS 1978 B)

• Small commercially available Locking Pliers

Removing

- If engine control module was replaced, select diagnostic object "Replacing engine control module " in "Guided Functions". Use a vehicle diagnosis tester.

- Switch off ignition and remove ignition key.

• Some engine control modules are not equipped with a protective housing. The removal and installation of the protective housing depends on the engine and transmission combination.

• 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.






• To disconnect the connectors from the ECM (for example to connect the test box or to replace the ECM), the protective housing must be removed.

- Remove the seal - 1 - and remove the plenum chamber cover - 2 -.






- Remove the windshield wiper arms - arrows -.







The wind cowl could be damaged.

• To prevent the cowl grille - 1 - from tearing when removing, coat transition between windshield and cowl grille with a soapy solution and pull grille up vertically out of fastening strip beginning at edge of window.








- Remove the bolts - arrows - and remove the cowl panel trim from the windshield.

- Remove bolts - arrows - and remove cover for E-box at right in engine compartment.







Risk of burning on heater pump valve unit (at left in front of E box).

• Wear protective gloves when working near heater pump valve unit.

- Carefully pry off the retaining clip - 3 - with a screwdriver - arrows 1 and 2 - and remove the ECM from the E-box.







Risk of damage (burning) from wiring and connectors, insulation and control modules.

• Follow the steps below carefully. Refer to the operating instructions for the hot air gun.

- Adjust the settings on the hot air gun - 4 - as illustrated:






2 Temperature dial set to the maximum heat setting
3 Air quantity switch in position "3"

• Next, the thread of protective housing in which the shear bolts is threaded in is heated using the heat gun. This step decreases the locking effect of the locking compound on the thread of the shear bolts, thus allowing the shear bolts to be unscrewed more easily.

• Cover all painted parts to prevent damage from the hot air gun or locking pliers.


There is a risk of burns.

• By heating the shear bolts, parts of the protective housing are heated intensely. Ensure as much as possible that only the shear bolt is heated and not the adjacent parts. Possibly cover these parts.

- Place the shrink tip for hot air gun (VAS 1978/15A) on the (VAS 1978/14A).






- Direct the hot air gun nozzle toward the shear bolt in the metal retainer.

- Switch the hot air gun on and heat the bolt for 20 to 25 seconds.

- Then hold the bolt head with locking pliers and remove the shear bolt.






- Repeat this on the second shear bolt.

- Remove both shear bolts - 3 - installed in the engine control module (J623) without heating them.






- Separate the retaining tab - 2 - of the control module connector.

- Release and pull off connectors from ECM.

• When the connector is disconnected from the ECM, adaptation values are erased but the content of the DTC memory remains intact.

Installing

Installation is performed in the reverse order of removal, noting the following:

- The ECM must be equipped with the protective housing again.

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

- Use new shear bolts.

- Install wiper arms.

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

- Activate the engine control module in "Guided Functions" under "replace engine control module". Use a vehicle diagnosis tester for this.