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.


Reading measured value block

Measured value block 001:

J Wheel speed front left

J Wheel speed front right

J Wheel speed rear left

J Wheel speed rear right

Display range 0 to 255 km/h. At vehicle standstill 0 km/h is displayed.

Measured value block 002:

J Brake test switch

J Brake light switch

JHand brake

JESP passive button

If one of these switches or buttons is pressed, the tester indicates pressed.

If unpressed, the readout is 0.

Measured value block 003:

J Engine speed (rpm)

J engine torque (Nm)

J Engine torque loss (Nm)

J Throttle valve angle (in %)

These data are required to calculate for the ABS/ESP control unit -J104.

Measured value block 004:

JStanding time (display range 0.0 to 255:59 h; standing time of the vehicle after ignition-off until

Ignition on. If no message from dash panel insert, text: ERROR;

Error status - standing time, text: Invalid.

The standing time signal is transmitted by the dash panel insert to control unit -J104. It is

required to calculate the brake cooling time.)

JEDS T-flag (possible readout Off or On; if "Off" 0K, i.e. the EDS system is

ready; if On NOK, i.e. the EDS system is shut off due to overheating).

J Vacant

J Vacant

Measured value block 005:

J Steering angle (possible readout in degrees, min. -720 max. +720, when

front wheels straight-ahead max. tolerance +/-5)

J Yaw rate (readout in degrees per second, min. -69/s max. +69/s

J Brake pressure (readout in bar min. -41 bar max. approx. 292 bar, by electrical faults, e.g.

short circuit to earth a value of approx. -40 bar is displayed, by short circuit to positive a

value of approx. 290)

J Lateral acceleration (readout in metres per square second;

display range min. -25m/s max. +25 m/s

Measured value block 006:

J Supply voltage term.30 for ABS/ESP control unit -J104 (OK 9.8V to 17.4V)

J Valve relay (possible readout Off/On; "On" OK, "Off" NOK)

J Status of return pump (possible readout: Off/On)

J Workshop code (readout: workshop code, tester code for relevant workshop)

Measured value block 009:

JBrake test switch Possible readout 0 and pressed

JBrake light switch Possible readout 0 and pressed

J Brake pressure

J Vacant

Brake pressure in bar min. -41 bar max. 292 bar, due to electrical faults, e.g. short to earth, a value of -41 bar is displayed; in case of short to positive a value of approx. 290 is displayed

Measured value block 21:

Data from sensor unit G 419

JNot relevant to service

JNot relevant to service

JNot relevant to service

Je.g. 0x0401 Hardware and software number in one byte

04 Hardware and 01 software

Measured value block 22:

Not relevant to Service (steering angle sender data)

Measured value block 23:

Not relevant to Service (variant coding data)

Measured value block 125:

JCAN message from steering angle sensor

JCAN message from engine

JCAN message from automatic gearbox (with manual gearbox no readout)

JCAN message from dash panel insert

Measured value block 126:

J Vacant

J Vacant

J Vacant

JCAN message from sensor unit (yaw rate and lateral acceleration senders)

Possible readouts: ESPSensors 1 = CAN message OK

ESPSensors 0 = CAN message n.OK

Measured value block 127:

J Vacant

JCAN message from airbag

Possible readouts: 1 or 0; if "1" OK; if "0" n.OK

If a 1 is displayed, a CAN message is sent from the relevant control unit.

  If the tester shows a 0, the CAN message is interrupted.

In such cases read the fault memory of the relevant control unit.

J Vacant

J Vacant


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