So without the current headlight schematic it might be a challenge here. I note from the old 2004 F53 schematic it shows the DRL connection take off after the steering column multi-function switch (of course that junction could be anywhere if it's even accurate for your 2016 coach chassis). Do your daytime running lights come on when the engine is running? (I am not sure if the coach has to be in gear; brakes off or not for DRL to come on and if they feed the low beam lamps. They should just come on with engine running I think? If DRL works and they are using the low beam elements, then your problem is between the DRL power junction and the two 10 amp fuses that feed the low beams. If DRL does not come on then the other approach is testing the dash light switch itself and multi-function control switch on the steering column with a voltmeter to see where the power is being lost.
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