Knorr A18 fault code reading


The system shows fault codes using flash codes. Fault codes are read out in the diagnostics socket by bridging 2 pins and connecting these in series with a 3rd using a test light.

To enable read-out of fault codes:

- Connect the positive (+) side of the test light to pin 1.

- Connect the negative (-) side of the test light to pin 4.

- Turn on the ignition (+15).

- Bridge pin 4 and 7 for at least 2 seconds.

- remove the bridging.

- Count flash pulses from the test light.

The first block gives information about the system configuration.

The second block gives information about where the fault is.

Block 1Block 2
Flash pulsesConfigurationFlash pulsesFault
22S/2M1ABS OK
  2Speed sensor DFA
  3Speed sensor DFB
  8Solenoid valve MVA
  9Solenoid valve MVB
  11Output ground valve A/B (GVR) Input ground control unit (GNDL)
  12Power supply
  13universal output
  14Internal error control unit

After the fault has been solved, erase the fault codes using the following procedure:

- Ignition off.

- Bridge pin 4 and 7.

- Turn on the ignition (+15).

- Wait for at least 2 seconds.

- remove the bridging.

- If the test light turns on, the fault code has been erased.

- Read out the fault codes again to check if there are more fault codes in the system.