Attention: The control unit is programmed with basic values for individual sensors. During operation, the control unit receives signals from sensors that, due to manufacturing tolerances and the condition of the engine, differ slightly from the programmed values. The new values are remembered and they change the control commands accordingly. This is in line with the process «learning».
When the control unit is switched on again with «erased» data or installing a new control unit, you must re-enter the engine data into the system. This process can lead to uneven idling and intermittent over-idling after start-up. The car needs to be driven for several minutes at various speeds until all values correspond to the state of the engine.
After installing a new control unit, it must be programmed by specialists at a service station. This requires a diagnostic/programming tool.
Removing
Before removing the control unit, it is recommended to read the contents of the memory unit of the diagnostic device in the workshop. This will help determine what the problem is.
Disconnect the negative cable from the battery with the ignition off.
Attention: This will erase data from the electronic memory blocks, such as radio codes.
Remove the side footwell trim and the fuel shut-off switch.
Drill out two or three rivets and remove the protective cover of the control box.
Pull the control unit out of the mount.
Unscrew the bolt of the connecting plug, remove the plug.
Installation
When buying a new unit, you need to know the number of the control unit and the coding. For identifications, it is recommended to take the removed control unit with you.
Insert plug. Tighten the bolt on the plug first by hand and then with a wrench so as not to damage the sensitive contacts of the plug.
Push in the control unit. Install the steel cover with new rivets. This cover serves as a safety feature so that the immobilizer does not work by mistake.
Install footwell trim.
Connect the negative cable to the battery. Set the clock, program the radio.
Make a 10-minute test drive at different speeds. At the same time, the control unit «is studying» new values of engine characteristics.