Re: Aux lights on dual circuit help
I played with this same problem wiring my light bar to come on with high beam with a bypass switch.
I'm assuming you've got DRLs?
If you're still using the Halogen bulbs (not sure on all aftermarket options) The two filaments share a ground and are not isolated. The relay takes much less switching amperage than the two sets of filaments in series can carry, so your AUX lights will come on with the parking lights or DRL, but go off once you power on the low beam at the stalk, as the bulbs now have a direct path to ground that doesn't pass through the DRL resistor.
Removing the DRL resistor (not sure you can do that in the UK) won't fix this either.
I've not got around to it, but you'll have to add an isolation relay to your hi-beam signal.
I planned to switch the contacts in my DRL relay and add a DPST relay to that slot so you now have a NC contact on that relay. This won't affect normal function.
THEN I'll add the second isolation relay, switched from this new DRL NC signal, to interrupt the feedback from the high beam circuit in all cases except when the high beams are actually on (and not just backfeeding through the bulb. Even my Hikari LED's will backfeed some and glow if the bypass circuit is on).
Last edited by RDTCU; 08-30-2019 at 05:38 AM.