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STEP 3: Blink code identification and system response

  1. If you already know how to read ABS Blink Codes from the ECU in question, please go straight to STEP 4: Blink code list
  2. If you are unsure how to read ABS Blink Codes from the ECU, start by familiarising yourself with the diagram below, and then, where appropriate, follow the step by step procedure in the table
  3. Please ensure all necessary Health and Safety precautions are implemented before commencing any repair work

Knorr-Bremse EU12 System ECU

Knorr-Bremse U16 System ECU

Step

Action

System Response

Notes / Comments

I

 

Connect a switch (Diagnostic Push Button) between the pin labelled 'DIA L' (X1/14) or labelled 'WL' (Pin X1/18) of the ECU and Ground.

If the Blink Codes do not display when the connection is made between 'DIA L' and Ground, switch to the pin labelled 'WL' and Ground. No damage is caused to the ECU as a result of choosing an incorrect connection.

 

 

Blink Code display (i.e. a sequence of flashes) may be initiated.

The Blink Code will be displayed on either the Dashboard ABS Warning Lamp (INA) or the Traction Control Warning Lamp (ASR). Consult the Vehicle Manufacturer’s Handbook to establish which lamp is used and where it is located.

In the absence of the Vehicle Manufacturer's Handbook, a bulb with a maximum power of 10 W can be connected between Ground and either the INA or ASR lamp pin of the ECU (see appropriate wiring diagram).

II

 

 

 

Switch Ignition ON (ECU powered).

Wait at least 1 second,

Then press Diagnostic Push Button twice as shown in the diagram above,

Then release button.

The ABS Indicator Lamp will illuminate whilst the button is pressed, and go out when it is released.

The ECU will then transmit two configuration code blocks, each block having two digits (see diagram above).

The transmission of the configuration codes can be terminated at any time, by pressing the Diagnostic Push Button.

III

 

 

 

Switch Ignition ON (ECU powered).

Wait at least 1 second,

Then press Diagnostic Push Button once for 2 to 5 seconds, as shown in diagram above,

Then release button.

The ABS Indicator Lamp will illuminate whilst the button is pressed, and go out when it is released.

The ECU will then transmit Blink Codes for any faults recorded on the ECU in blocks of two digits (see diagram above).

The transmission of the fault codes can be terminated at any time, by pressing the Diagnostic Push Button.

See Step IV below for how to interpret the ABS Indicator Lamp flashes.

IV

 

Count the flashes from the ABS Indicator Lamp.

Write down only the first 4 or 5 Blink Codes for faults recorded on the ECU (there may be several stored in the memory).

Following each Blink Code a period of approx. 3 seconds elapses before the next Blink Code is displayed.

The Blink Code for a fault is in two parts: the first digit represents the component number, and the second digit the failure mode.

The ECU is able to store up to 192 different faults.

After the final Blink Code has been displayed, further pressing of the Diagnostic Push Button will result in the first fault being repeated.

If the Service Brake has not been actuated after power up, this will be shown as a Brake Light Switch (BLS) fault.

V

 

Turn Ignition OFF

Determine if faults recorded in III above are active or stored:

 

 

 

 

Active Faults: Will reappear (repeat) after any Blink Codes have been deleted from the ECU.

Stored Faults: Will be cleared when Blink Codes are deleted from ECU.

NOTE: Last fault stored is first fault displayed.

 

VI

 

Clearing ECU fault memory:

Whilst pressing the Diagnostic Push Button, switch ignition ON, and hold button for a further 3 seconds.

Release button and the memory is cleared.

The ECU self-configures after the memory has been cleared.

The ECU self-configures to the status of the system at the time of ‘powering up’ and so any component connected after configuration has taken place will not be recognised by the ECU.

 

 

VII

 

Turn Ignition OFF

 

 

 

VIII

 

Repeat steps II and III above.

Record Faults (Blink Codes).

Only active faults will be shown now.

 

To identify blink codes, refer to the Blink Code List. Make the necessary repairs to active faults. Repeat Step VI (Clearing ECU fault memory), then road test the vehicle. The warning light should go out.

If the warning light remains after road testing, go back and repeat steps II , III and VII again until the warning light does go out.

Record faults for future reference

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