Retrieving Diagnostic Trouble Codes
The Anti-Lock Brake System ECU (Z108) is capable of storing fault codes. These codes can be read using the Wabco Diagnostic Controller, part number 446 300 300 0, or by following the flash code procedure. Use of the Wabco Diagnostic Controller is recommended.
If the Wabco Diagnostic Controller is not available, the flash code procedure can be used to retrieve the fault codes stored in memory. The fault code is read by counting a series of ABS warning light flashes and pauses. Reading of the flash code aids in determining the location of the fault and can reduce diagnostic time. In order to initiate the flash code mode, use a female plug designed to fit the ABS Diagnostic Connector (X104). See Fig 1 . The plug should be pre-wired to connect the Diagnostic Connector's BK and B terminals. To initiate the flash code, carry out the following procedure:
- Locate the Diagnostic Connector and Warning Relay (K103) under the left front seat. Disconnect the relay. See Fig 2 .
- Place the ignition in position II.
- Connect the plug to the Diagnostic Connector.
- Approximately 5 seconds after connecting the plug, the warning light should go out, indicating the start of the flash code cycle.
- Observe the warning light. The start phase consists of the following: pause for 2.5 seconds, flash for 2.5 seconds, pause for 2.5 seconds, and flash for 0.5 seconds. The following figure illustrates the start phase. See Fig 3 .
- First part of code number consists of the following: pause of 2.5 seconds is followed by a series of short flashes. Count the flashes until the next long pause occurs. The number of flashes counted is the first part of the code number.
- Second part of code number: pause of 2.5 seconds occurs between the first and second part of the code number. Count the number of short flashes that occur after the 2.5 second pause. The number of flashes counted forms the second part of the code number. The following figure illustrates the start phase. See Fig 4 .
- The whole cycle will continue to repeat itself until the operator terminates the process. This allows the operator to re-check the code number.
- To terminate the process, disconnect the plug from the Diagnostic Connector. Termination of the process will clear the code recorded from the ECU memory.
- The ECU is capable of storing more than 1 code. To search the memory, reconnect the diagnostic plug and wait for the next start phase. The ECU memory is clear of all codes when a pause of 7.5 seconds occurs after the start phase.
- Reconnect the Warning Relay.