Security (Diagnostics): Description and operation

Diagnostics

A diagnostic socket allows the exchange of information between the CCU and the immobilisation ECU and TestBook. The diagnostic socket is located in the driver's footwell and is constructed to ISO standard. A dedicated diagnostic bus is connected between the socket and the instrument pack and allows the retrieval of diagnostic information and programming of certain functions to be performed using TestBook.

The CCU and the immobilisation ECU monitor all inputs and outputs and if a fault is detected a code for that fault is stored in a fault log.

The CCU has two fault logs for internal and external faults. The CCU is capable of detecting short or open circuits. The CCU will disable certain functions when faults are detected and reinstate functions when faults are corrected and the function is again requested.

The immobilisation ECU also stores fault codes. The diagnostic interface is also used for matching a replacement ECM to the existing immobilisation ECU.