Daytime Running Lamp: Testing and Inspection

The complexity of the electronics involved with the Body Processor and the two multiplexed communication networks which are associated with it, preclude the use of workshop general electrical test equipment. Therefore, reference should be made to the Portable Diagnostic Unit (PDU) User Guide for detailed instructions on testing the Daytime Running Function.

The Daytime Running function is exactly the same as for the normal operation of the side lamps (or dipped beam, where specified) in as much as the body processor drives the same lamps from the same outputs.

The body processor has been programmed to respond to an alternative set of conditions in order to operate the lamps, instead of waiting for a signal from the normal light switch.

The conditions which have to be set are; ignition switch set to position II or III and sidelight switch set to OFF The sidelights, side marker lamps (if fitted and enabled), tail lights and number plate lights will all be switched ON.

The PDU systematically tests and analyses all functions of the daytime running lamps.

Where a fault is indicated, some basic diagnostic methods may be necessary to confirm that connections are good and that wiring is not damaged, before replacing a component.