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need help with replacement headlamp wiring harness

4262 Views 0 Replies 1 Participant Last post by  t2000kw
I have a 2009 Mazda 31 with standard halogen headlamps. I have a problem with the low beam headlights. They worked for the first few weeks after I (recently) purchased it and now they will initially turn on then go out before I get more than a few yards down the street.
The bulbs test fine and they work in my 2005 Mazda 3i when I swap them between cars. The headlight fuse in the fuse box under the hood tests fine and has power through it.

I understand that some have had trouble with the headlamp relay and it’s supposed to be somewhere in the passenger compartment. I also am aware that the relays are integral to the inside power distribution box so I plan to wire up a bypass circuit.

I purchased a headlamp wiring harness that has two relays on it. I haven’t looked it over carefully but my plan was to use it only for the low beams since the high beams work fine. It has relays for the high beam and low beam and was made for the dual hi/lo bulbs but I will cut off the connector to the bulb and just splice into the original wiring to the bulb.

I’ve read about this sort of problem in several forums and it never seems to be answered (at least in the threads I’ve read through), so that’s why I decided to create a separate circuit to replace the original one for the low beams.

My questions:

1.) Where do I tie into the original circuit for the relay energize voltage, and where to tie in for the power to the low beam bulbs. I don’t have a wiring diagram book yet for this car so I can use some help here, especially for the wire from the headlamp switch to the original relay.

2.) Is there any value in using one of the relays for one side and one for the other side, perhaps just to have less current through the relay contacts?

3.) Is it safe to just use the original ground to the bulb sockets (I’ll need a ground for the relay coil, of course) or should I also wire in a ground and tie that in as extra “insurance” against a ground problem at a later time?

Thanks in advance. I am posting this in a few Mazda forums so if you frequent other forums, you may see this.

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