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.


Description of drive and system test, Bosch 8.0


Asee function test, J104 - ESP drive and system test


The ESP drive test checks the sensors in the ESP system.

JLateral acceleration sender -G200,

JYaw rate sender -G202

JBrake pressure sender -G201 in ESP system

Once the ESP drive test has been started it cannot be aborted and must be completed.


J After quitting diagnosis the ABS lamp remains on to indicate that the test is active. The ABS and ESP functions are disabled and not operative.

J Compliance with road traffic regulations and observance of traffic conditions always has top priority.

J The diagnostic tester is not required to perform the drive and system test. Take the diagnostic tester out of the vehicle.



- The vehicle must be standing on a flat surface

- Activate the drive and system test by Guided Fault Finding

- Unplug the diagnostic connector from the diagnostic tester

- Start the engine

J ESP lamp in dash panel insert lit steadily and fault 01486 System test active entered in fault memory

- Press the brake pedal down forcefully > 45 bar (standstill readout)

J The ESP lamp goes out and the ABS lamp lights

-Run a right-hand and left-hand bend at a speed of v = 20 ...30 km/h

J If the ABS lamp goes out, the test is passed.

If the ABS lamp remains lit, the test is n.OK (system locked) and must be repeated.

- The manoeuvre can be repeated by switching the ignition off and back on and pressing the brake.


Lamp activation for drive test:

Drive test ESP lamp ABS lamp Brake warning lamp

Active on off off

Brake pedal pressed off on off

Drive checks OK off off off

Fault in ESP system on on on


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