Engine Control Module

Engine Control Module

The multi-pin harness connectors of Engine Control Module (ECM) are equipped with a protective housing secured by a locking mechanism and shear bolts - arrows -. Also to impede removing of the shear bolts, their threads are coated with locking compound.





The protective housing must be removed so that multi-pin harness connectors can be disconnected from ECM, for example to connect the test box or to replace the ECM.

Special tools, testers and auxiliary items required

• Hot Air Gun (VAS 1978/14)

• Shrink Tip for Hot Air Gun (VAS 1978/15)

• Locking Pliers (commercially available)

Removing

- Turn the ignition and remove the ignition key.

- Pry cover caps off windshield wiper arms using a screwdriver.

- Loosen nuts - arrows - several turns.





- Loosen wiper arms one after another by tilting wiper axles slightly.

- Remove nuts completely and remove wiper arms.

• If wiper arm cannot be removed in this way, use a standard puller.

- Remove rubber seal - 1 - and remove plenum chamber cover - 2 - by carefully removing cover from retainers on windshield.





- Free up the rear engine wiring harness at the partition for plenum chamber.

- Remove bolt - arrow - and remove engine control module (ECM) from bracket.





- Disconnect electrical connector - arrow - for body wiring harness - 1 -.





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.

- Adjust settings on hot air gun as depicted in the illustration, this means potentiometer - 2 - for temperature setting at maximum heat output and two-stage switch - 3 - for air quantity at 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 removed more easily.

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

By heating the shear bolts, parts of the protective housing are heated intensely. Do not burn yourself on this! Make sure that only the shear bolt is heated if possible and no other components in the vicinity are heated. Possibly cover these parts.

- Perform the following work steps in succession at both shear bolts - arrows -.





- Place (VAS 1978/15) on (VAS 1978/14).





- Guide hot air gun shrink tip onto protective housing shear bolt.

- Switch heat gun on and heat bolt for approximately 20 to 25 seconds.

- Grip bolt head with pliers and remove shear bolt.





- Slide protective housing - arrow 1 -.





- Disconnect electrical multi-pin connector - arrow 2 -.

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

Installing

Installation is in reverse order of removal, note the following:

- Install the engine control module in the housing.

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

- Use new shear bolts.

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

- Activate engine control module (ECM) in "Guided Functions" under test sequence/function "Replacing engine control module (ECM)".