ECU - Electronic Control Unit

In terminology of VW-group it's any electronic device, which has been carried out some logic function. Sometimes it looks like nonsens - even simple relay can be called ECU.

The coding of Electronic Control Unit used for explain the ECU where it is and what "neighbours" does it have. Very often on modern cars the coding is crossed with adaptation.

Adaptation of the Electronic Control Unit serves to explain to the ECU with whom and how to talk (If we have started to speak allegories) and serves as storehouse of various adjustable parameters. ( part of memory in the Control Unit which can be changed via internal software )

Measured Values Blocks ( MWB ) – various parameters being inbound or calculated. Considering to value of MWB Electronic Control Unit, trying to "control"... Using of MWB allows you ( if you know the basic parameters ) to find out "close to boundary" or temporarily arising ( intermittent, sporadic ) malfunctions and many other useful things at competent use.


Procedure for replacing control unit

A see function test

J104 - Replace control unit

In this test the coding is performed automatically. The precondition is that communication with the control unit is maintained.  If no communication can be established with the control unit, the function test:

AJ104  - Code control unit must be performed.

A Removing and installing control unit -J104 see ELSA Brake System, Rep.Gr.-45

Following coding the steering angle sender must be calibrated. The control unit coding and steering angle sender calibration no longer need to be performed in one terminal 15 cycle.


K Note: The new control units are shipped uncoded from the spares store, which means as a general rule the encoding code of the defective control unit is valid for the new control unit, with same control unit index.


There is no longer a login code in the Bosch 8.0  ESP system

The encoding code comprises four different variants (brakes, engine, gearbox, air spring). The variants must be defined based on the production number (see Audi Service Plan or label in spare wheel well).


The coding of the ABS/ESP control unit is checked for accuracy (adaption and coding) with the following control units


- Airbag-

Select function 10 Adaption

Channel 50 drive variant

Value 0 = No variant stored

Value 1 = Front-wheel drive

Value 2 = quattro

Channel 51 brake variant

Value 2  = C54 Lucas 1LZ

Value 4 = FN3 Teves 15 inch 1LB, 1LE

Value 6 = FN3 Teves 16 inch 1LT

Value 12 = FNRG-60 16 inch 1LA/1LD

Value 14 = FNRG-60 17 inch 1LJ

- Engine-               

Combustion method,

number of cylinders,

gearbox coding

- Gearbox-

Coding in engine control unit


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