Manufacturer's Scan Tool
Engine Control Module, Replacing
• When the engine control module is disconnected, the learned values are erased but the contents of the Diagnostic Trouble Code (DTC) memory remain intact.
Removing engine control module
- Connect vehicle diagnostic, testing and information system VAS 5051 and select vehicle system "01 - Engine electronics" from list. Ignition must be on.
The display on V.A.S 5051 shows control module identification code and code - 2 -.
- Display and print out control module identification.
- Switch ignition off.
- Remove rubber seal of plenum chamber cover in direction of - arrow -.
- Remove plenum chamber cover - 1 - to front.
- Pry off two caps - 3 - using screwdriver.
- Loosen hex nuts - 4 - by several turns.
- Loosen wiper arms - 2 - from wiper shaft by tilting slightly.
- Remove hex nuts and detach wiper arms.
- Remove securing clips - 1 - and detach cowl panel grille - 5 -.
- Remove cover for electronics box in plenum chamber - arrows -.
- Carefully pry off fastener - arrow - using a screwdriver.
• Item - 1 - in illustration shows engine control module with protective enclosure.
To render access to the connectors on the engine control module more difficult, the engine control module - 1 - is bolted by the way of a catch - 2 - and shear bolts - 3 - to a protective enclosure - 4 -.
Locking fluid is applied to thread of shear bolts to make bolts more difficult to remove.
Engine control module must be separated from protective enclosure. To unplug connectors from engine control module (e.g. when connecting up test box or replacing engine control module). This procedure is described in the following.
Tools required:
• Hot-air blower - 1 - (from wiring-harness repair set VAS 1978)
• Nozzle attachment - 2 - (also from wiring-harness repair set VAS 1978)
• Commercially available locking pliers
Removal:
CAUTION!
To avoid damaging (scorching) wires, connectors, insulation and control modules, always adhere to the following operations and observe operating instructions for hot-air blower.
- Tilt engine control module with protective enclosure toward engine compartment so the catch (item - 2 -) becomes visible, and place a clean cloth beneath engine control module with protective enclosure.
- Make settings on hot-air blower as shown in illustration, i.e. set temperature potentiometer - 2 - to max. heat output and two-stage air flow switch - 3 - to position 3.
• Then use hot-air blower to heat thread of catch into which shear bolts are screwed. This operation is designed to reduce the inhibiting action of the locking fluid on the shear bolt thread to make it easier to screw out the shear bolts afterward.
CAUTION!
Heating the thread of the catch also greatly increases the temperature of the shear bolts and protective enclosure components. Take care to avoid burns. Make sure that only the thread is heated and none of the surrounding components if at all possible (these should be covered if necessary).
- Move nozzle - 1 - of hot-air blower toward thread of catch such that nozzle "surrounds" thread. Allow nozzle to rest on upper end of protective enclosure.
- Switch on hot-air blower and heat thread for 20 to 25 seconds.
- Grasp head of bolt - 2 - with locking pliers - 1 - and screw out shear bolt in direction of - arrow -.
Use the same procedure for the second shear bolt, taking particular care to avoid the control module connectors in the immediate vicinity.
- Move nozzle - 1 - of hot-air blower toward thread of catch such that nozzle "surrounds" thread. Allow nozzle to rest on upper end of protective enclosure.
- Switch on hot-air blower and heat thread for 20 to 25 seconds.
- Grasp head of bolt - 2 - with locking pliers - 1 - and screw out shear bolt in direction of - arrow -.
Engine control module can now be separated from protective enclosure.
- Release connectors of engine control module and disconnect.
- Take out old engine control module and insert new one.
Installing engine control module
Install in reverse order of removal; protective enclosure is always to be reinstalled to engine control module. New shear bolts must be used.
The following operations must be performed after installing the engine control module:
- Adapt immobilizer to: Motronic Engine Control Module (ECM) (J220) (otherwise vehicle will not start).
- Encode new engine control module.
- If vehicle is installed with cruise control system (can be seen from steering column switch), this must be released in engine control module.
- Check Diagnostic Trouble Code (DTC) memory and erase, if necessary.
- Activate engine control module in "Guided Fault-Finding" routine under diagnosis item "Replacing engine control module".
Vehicle diagnostic, testing and information system VAS 5051 is to be used for this purpose.