Engine management system - EDC (Diagnostic connector): Description and operation

Diagnostic connector

The diagnostic connector is located behind the passenger’s ’A’ post lower trim panel. The diagnostic connector is provided to enable diagnosis via TestBook to be carried out without disturbing the system electrical connections and to allow the engine control modules ability to store certain faults to be utilised.

Malfunction indicator lamp

The engine control module has a built in self-diagnosis function. If a fault is detected the malfunction indicator lamp (MIL) in the instrument pack will illuminate, and the control module will implement a back-up facility to enable the system to continue functioning, though at a reduced level of performance. If a serious fault is detected the warning light will illuminate and the engine management system will shut down preventing the car from being started or driven.

The MIL will remain illuminated until the starter switch is turned off. If the fault is still present when the starter switch is turned back on the MIL will illuminate. If the fault is not present when the starter switch is turned on, the MIL will remain extinguished, but a fault code will be stored in the engine control modules memory.