Help! How can I get my low beams to stay on with high beams?

I am using a friends pair of projectors he never ended up using. His truck had separate high beams, so this wasnt an issue for him, so he has the regular harness.

Our Explorers (Well, 1st, 2nd, and 4th gens) use one bulb as low and high. Problem is, if I flick my high beams on, the cutoff shield will rise, BUT the low beams will turn off, turning the ballasts off.

I read online someone said wire a diode in between the low/high beam wire on whatever side you use as the input to the HID harness. Everytime that was mentioned, that was all. Nothing about how, or where or what type. I can wire things good, but when it comes to electrical terms and little gadgets, I get lost.

Can anyone explain what diode I would need, and would a store like RadioShack sell them? I would need just one I believe, right? Thanks in advance!

I figured out how it works, but im stumped as to what one I need. Ill only need one because the harness that plugs into the TRS harness only needs one input anyways. It wont actually be carrying the amperage of headlights, so I dont need a high amp rated one, right?

 

[DjDom]

I would take the relay approach. When you turn the high beams on, it triggers the relay which then in turn causes the low beam relay to be shut off.

I do recall reading somewhere on this forum a way to make high and low beams stay on at the same time. I'm pretty sure it involves jumping the relay. This would work for stock halogen bulbs, so for the HID retrofit as well.

 

[Anime]

Bi-xenon Relay Harness
A bi-xenon harness is a bit more complicated compared to a standard low beam wire harness. A typical dual-filament halogen bulb has 3 pins: one for the low beam, one for the high beam, and a ground. In low beam or high beam mode; only that pin is receiving a signal from the factory harness. The low beam mode is simple, but in a bi-xenon retrofit, you need the low and high beams powered on at the same time. Otherwise, when you hit the high beams, the projectors will turn to high beam mode but the ballasts will turn off - leaving you with nothing but darkness. A properly configured harness will correct for this problem. There are two ways a bi-xenon harness can be setup to do so:

With a diode:
The diode will be installed between the low and high beam input wires on the harness. A diode is a like a one-way road that lets current flow from the high beam lead into the low beam lead - which not only keeps the relays powering the ballasts but passes through to the bixenon solenoids to activate the hi beam.

With a control box:
This will control the function of the low and high beams via it's own specialized/smart circuitry. When the control box reads "low beam input pin active" it will only output power to the ballasts. When the control box reads "high beam input pin active" it knows to send current to the ballasts and the bi-xenon solenoids at the same time. These are more complicated and less serviceable, but often times more universally applicable with positive and ground switched circuits.

https://www.theretrofitsource.com/knowitall/wireharnesses.html/


You can just google "HID diode" and get a bunch of diode info, seems like lots of people were using 3 Amp Radioshack diodes (with a 200A surge rating) for HID systems. Most Radioshacks are now closed, but you can still get diodes at other electric supply or hobby shops, or buy online.