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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 information below, and then, where appropriate, follow the step by step procedure
  3. Please ensure all necessary Health and Safety precautions are implemented before commencing any repair work

Wabco VCS II version ECU

Wabco VCS II version ECU

Blink Code Diagnostics

The WABCO Vario Compact II Trailer ABS ECU detects any electrical fault in the trailer ABS. Each of the faults has a code. When a fault occurs, the ECU stores the code for that fault in the memory.

There are two kinds of faults: active and stored. Active faults are those currently existing in the system, such as a broken wire. Stored faults are faults that have occurred but do not presently exist. Active faults can be cleared only after repairs are completed. Stored faults can only be diagnosed with TOOLBOX Software or the Pro-Link 9000.

The ECU signals a malfunction by lighting both the internal and external indicator lamp when a fault exists. The external ABS indicator lamp is usually mounted on the left rear of the trailer, near the rear wheels.

There are two ways to obtain blink codes:

  1. Ignition Power Activation (recommended method)
  2. Diagnostic Tool


In previous versions of The Vario Compact system, the blink code tool and the ABS indicator lamp would flash the blink code at the same time. With Vario Compact II, this does not happen. The codes are displayed one blink at a time, first on the trailer ABS lamp, then on the blink code tool.

Although the ECU can store multiple faults in its memory, it only displays one blink code at a time. This is why it is important to recheck the blink codes after repairing a fault. If there are additional codes in the memory, they only blink after you have repaired the first fault. Stored faults, clear all and end of line test modes are available with the TOOLBOX Software or the Pro-Link 9000.


Ignition Power Activation

Ignition Power Activation is the process of using the vehicle’s ignition switch (or interrupting the power on the blue wire by some other means) to display blink codes on the trailer ABS indicator lamp located on the side of the trailer. This method is for constant power vehicles only.

To obtain blink codes using ignition power activation, perform the following procedure:

  1. Turn the ignition switch on for no longer than 5 seconds. The ABS indicator lamp will be on.
  2. Turn the ignition switch off. The ABS indicator lamp will go out.
  3. Turn the ignition switch on. The ABS indicator lamp will then come on, then go out.
  4. The blink code will be displayed three times by the ABS indicator lamp on the trailer.


For ignition power activation, power is provided by the ignition switch.

As with the WABCO Vario Compact (1st Generation) system, the casing of the ECU unit for the Vario Compact II is clearly labelled with indicators as to where the various parts of the ABS system are to be connected. For example, if the blink code identifies that sensor YE2 is faulty, then by looking at the exterior casing it is a straightforward task to identify where on the vehicle sensor YE2 is located - you just follow the routing of the cabling from the ECU. See above diagram for more detail.

For a comprehensive list of all the blink codes for the Vario Compact II ECU, refer to the Blink Code List.

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