Daylight running lamps

The BCU operates the daylight running lamps (where fitted) via the IDM. The daylight running lamps option can be programmed in one of three states dependent on market/ customer requirements, these are:

• Option 1- no daylight running lamps.
• Option 2 - on with main beam off.
• Option 3 - on with main and dipped beam off and gearbox not in Park.

The BCU will ensure the logical conditions are satisfied for the lamps to operate under the set conditions. The BCU checks the status of the following inputs to determine the logic action for providing an output to the daylight running lamp relay:

• Main beam state.
• Engine running (link from instrument pack).
• Dipped beam.
• Gearbox state.

A voltage supply is fed to the coil of the daylight running lamp relay and the IDM. When the preconditions are satisfied for daylight running lamp operation, the BCU sends a signal for the IDM to complete the circuit to earth to switch on the daylight running lamps. The logical inputs are checked to ensure that the engine is running before switching the relay to turn on the daylight running lamps. The engine running signal has to be present for at least 2 seconds before the daylight running lamp relay can be switched on.