Engine Control Module: Service and Repair
Engine Control Module (ECM) (J623)
Special tools, testers and auxiliary items required
• Heat Air Blower (VAS 1978/14A) with nozzle attachment from the Wiring Harness Repair Set (VAS 1978 B)
• Puller (T10369)
• Small commercially available locking pliers
Removing
- Read the adaptation values for the fuel injector and ash content before removing the Engine Control Module (ECM) (J623). Use a vehicle diagnosis tester.
- Save the adaptation values as a file.
- Switch off the ignition after saving the file and remove the key.
• Some ECMs are not equipped with a protective housing. The removal and installation of the protective housing depends on the engine and transmission combination.
• If the injector adaptation values from the faulty ECM are no longer readable, they must be manually entered and adapted in the new ECM.
• The 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.
- Turn the ignition and remove the ignition key.
- Pry off the caps on the windshield wiper arms using a screwdriver.
- Loosen the nuts - arrows - by several turns.
- Loosen wiper arms by tilting slightly from windshield wiper axle.
- Remove the nuts and remove the windshield wiper arms from the wiper axles.
• If it is not possible to remove the windshield wiper arms this way, use the (T10369) or a commercially available puller.
- Remove rubber seal - 1 - and remove plenum chamber cover - 2 -.
- Open the clamp - arrow - and remove the ECM.
• Cover painted surfaces with a cloth to protect against scratches.
The threads of the shear bolts - 4 - (that are not installed in 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 installed in 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 the maximum heat and the two-stage airflow 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.
Warm threads on connector side of the shear bolts as shown in illustration.
Switch on heat gun and heat the bolt for approximately 20 to 30 seconds.
- Remove shear bolts with suitable locking pliers (see direction of - arrow -).
- The shear bolts installed in the ECM do not need to be heated for removal. They can be removed without heat.
- Separate the protective housing from the control module connectors.
- Disengage the connectors from the ECM and disconnect the connector.
Installing
Install in reverse order of removal.
- Thereafter, the ECM must be equipped with the protective housing.
- Clean threaded holes for shear bolts of locking compound residue. Cleaning can be performed with a thread cutter (tap).
- Always use new shear bolts.
- Install the windshield wiper arms.
The procedures to follow after connecting the new ECM are described in Guided Fault-Finding and Guided Functions. Use a vehicle diagnosis tester.
- After replacing the ECM, the injector quantity calibration and the injection pressure calibration must also be re-adapted into the ECM (the injector quantity calibration and the injection pressure calibration influence engine performance and emissions).
- The actual kilometer must be stored in the ECM via an adaptation on vehicles with a particulate filter.