When replacing a control unit it is necessary that the variant code is correct. The variant code can be read from the old control unit as a data list parameter "Variant coding". Valid variant code is also found in workshop manual or similar.
Note:
A faulty variant coding can reduce the car safety and/ or performance.
A workshop manual or variant code from old control unit must be available.
The control unit version must be correct to accept variant coding.
Some control units can not be variant coded.
Test prerequisite:
A valid variant code for control unit.
The value "short code" should presented in the parameter "Controller, variant coding".
The battery voltage should be above 12V
Ignition on, engine off.
All the electrical loads should be switched off.
Procedure:
If possible, read the variant code from the old control unit.
Start the function "Code control unit"
The actual code in control unit is presented. "Change value is presented". Confirm with YES.
Enter the new variant code in the presented input field, confirm with OK.
A dialog box will confirm: code stored (with the new value) in memory. If the variant coding operation fails, check if the variant code is valid.
Confirm with OK to exit the function.
Switch off the ignition for 60 seconds to store the new code.
Read and check the fault codes. Read the parameter "variant coding" to check if the new code is stored.