Okay, I think I've figured it out, but I'd still like some help/confirmation with this. I just got an H4 Headlight Conversion Harness from Black Dragon Auto. I noticed an extra plug on the harness. I know the two sockets are for the headlights and the two red wires go to the battery. And, at the time, I couldn't figure out what this extra plug was for. But now, I'm figuring it's to plug into the stock headlight wiring so that when I flip the switch, the headlamps will flip up and the headlights will light.

Can anyone else verify this for me? I'm tired, I'm hungry, and can't go out to peek under the hood of my car right now to see if there is such a plug to accept this plug. Help would be appreciated, thanks.

 

I didnt look verry well but i pulled up the shop manual for the 85 and i think that that would plug into your switch or the yes the stock lead comming from the switch. and judging by the length of the lead from the relays and the connectors to the head lights

 

Looks like it plugs into one of the headlight sockets to me. How else would the harness know when you had the lights on, and whether it was high or low beam?

 

I have the same harness. That is the Left Side connector, and it plugs into the headlight portion of the original, factory harness to operate the relays.

In other words, it looks like the back of a bulb because your factory harness needs to connect to it somewhere so that you have a power lead from the steering wheel switch to make the relays run.

The company who made these went out of their way to make it an easy plug-and-play installation. The reason why this will work better for your car and headlights is that it removes the need for the electricity to go through the steering column switching mechanism and then back out to the bulbs through the 18-22 (small) gauge wiring that Mazda used. Instead, it uses relays to switch short, clean power through 16 gauge wire so that each bulb gets a full 12 volts on short leads.

It's a good product, and installation should be a snap. HTH,