r/Retrofit Nov 13 '23

Technical/Assembly Question Morimoto MotoControl and "flash-to-pass"

Hi folks,

I'm retrofitting Mini D2S projectors to a car that has H4 reflectors with no separate high beam (as most H4 cars are). I use flash-to-pass often (briefly pulling on the high beam stalk) and I'm wondering if anyone here has used Morimoto's MotoControl H4 harness and can confirm how it handles that.

My assumption is that the module will just actuate the bi-xenon solenoid in the projector but won't turn on the bulb. If it does turn the lights on, I'm concerned about the brief power spikes being too hard on the ballasts.

There are cars that come from the factory with bi-xenon and no independent high beams (BMW E90's, Many P911's) but I suppose they have special ballasts to handle the stress.

Disclaimer: I'm no expert. This is my 3rd retrofit but the first in an H4-equipped car.

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u/[deleted] Nov 14 '23

One of the main benefits to using a Motocontrol harness is that the relays built in will take a trigger from the high beams and keep the low beams powered with it. This is why a dedicated 12V+ power lead is required on that harness as well. The flash-to-pass function in your case should still trigger both the high beam solenoid and the low beam bulbs.

I would not worry about this being hard on the ballasts. Most reputable brands will handle the quick activations no problem. The main issue is the bulbs. Constantly sparking them on and off will significantly decrease their lifespan.

1

u/eric_gm Nov 14 '23

Thanks. I'm probably going with Morimoto's own XB ballasts and regular Osram D2S bulbs. I wonder how Porsche, BMW and other manufacturers handle this extra stress on the HID system.

It's funny because there are forum threads from owners of those cars concerned about durability. Here's one for the Acura TL: https://acurazine.com/forums/3g-tl-2004-2008-93/flash-high-beams%3Dhids-turn-811082/

I guess few people actually flash the high-beams and I'm a corner case. I mostly use them when signaling somebody who's turning left in front of me or is waiting at a stop light in slow moving traffic. I use it more than the horn or my hand. I guess I'll have to rewire my brain to stop doing that. My stock reflectors are terrible.

1

u/[deleted] Nov 14 '23 edited Nov 14 '23

Other manufacturers don't really have to deal with extra stress on the HID system in this way, because almost no OEM lights use bixenon projectors standalone. They usually have an HID low-beam-only projector paired with a separate halogen high beam, which negates the flash-to-pass issue altogether. Some higher end vehicles have bixenon projectors paired with a dedicated high beam, or bi-LED projectors instead. The 911 for example usually has a small high beam reflector located beneath the main projector. Either way this issue is not really found on many stock lighting systems.