Wiring driving lights to come on with highbeams

You better check that they are legal that way. If you were in Pennsylvania it would be illegal.

Easiest way is to put them on a switch and circuit by themselves.

Yes, I realize that would be easier, but that's not what I want.

Aside from the fact that it may be illegal as other posters have already mentioned; I am guessing that you may have a poor ground to your headlights such that the high beam filament and relay coil is a good enough ground path for the low beam filament that there is some backfeeding. Alternately, you may have a vehicle where the lights are ground-switched. It's odd, but I've heard of some Japanese cars being wired that way.

nate

What does that mean, ground-switched? If that were the case how would I make it work?

My first impression would be to check the relay's wiring closely to make sure, then if the relay is wired correctly, I would see what the line I tapped into reads with the multimeter.

If it reads 12 volts from the wire to ground with the low beams on, you have tapped into the wrong wire or a ground switched one.

A ground switched light can have a power to ground potential in the wires when the light is off, the ground is broken at the headlight switch. Unusual... That would just mean you need to tag the low beam bulb for trigger power.

Mike

Other side of the relay to +12, instead of ground.

yes some japanese cars are wired that way. It saves wiring since the B+ is already there under the hood. Plus, if there is a short circuit, the max load through the light switch is minimized by the fact that the light comes between B+ and the switch.

Certain US company didnt like the idea of constant B+ to the lights. I think they felt it caused some form of corossion.

Yes, in the US/Canada it tends to be illegal. Thats why fog lights and turn off when high beams turn on.

You didnt splice into one of the leads for the high beams. Where is your power source for the relay?

Where does one find the room to run high beams or driving lights these days? I used to have DL's capable of lighting up a mile fo road in the 60's, but now, I almost never find a spare minute without oppsosing traffic.. =20

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I used to work in Beltsville (MD) and live in Bowie; towards the end of my employment at that company I had to do some site work after hours near Ft. Meade. I'd use my brights quite a bit and was quite happy that I'd seen fit to put a relay harness and E-codes in my 944, as when driving on 197 at 1-2AM it tends to be fairly dark and deserted (and there's an occasional deer, too...) I would say that I was able to pick up a good 20 MPH safely by upgrading my headlights, and when you've been working for 14+ hours and are on your way home, that's important :)

nate

(no, they're not legal, and neither were the 100W bulbs that they came with, but they sure are damn nice. Nobody ever flashed me though - E-codes don't glare on low beam, period, unless they're misaimed.)

The problem is that current driver thinking is to run them regardless of traffic. Drive down the road and look at the morons running fog lights full time....

That's a pretty stupid thing to do.

You must have spliced into a low beam lead, or spliced into a lead which was carrying earth return current.

The correct way is to wire them so that you need high beam AND a switch to be on before the DLs turn on.

I presume that you have a DRL equipped Accord. What has probably happened is that you have spliced into the highbeam B+ wire that goes to either the left or right highbeam filaments. If you have DRLs, then there is a DRL module that sends a "half voltage" output to the highbeams anytime DRLs are requested (simplistic explanation but good enough for this purpose). Any voltage on this wire will probably be sufficient to close your fog light relay and turn them on when you don't want them on.

I would suggest you go to the headlight switch (combination switch) and wire one side of your relay coil to the solid orange wire (grounded when the headlight switch is in highbeam position or "flash to pass"), then wire the other side to a dashboard mounted switch which is then wired to fused ignition power. The two high current contacts of the relay will remain the same, as they obviously work OK.

To avoid problematic B+ potential at the DRL module, you will need to wire in two diodes to isolate the fog light relay from the rest of the system. Go to Radio Shack and get a two-pack of standard 50 volt diodes for about $3. Note that the diodes each have one stripe or "band" on them, nearer one end.

Now, visualize the orange wire and the point on it where you spliced into it with the foglight relay lead. You want to cut the orange wire on both sides of that splice, and solder in the diodes. In the cut you made between the combination switch and the splice, you will put a diode in with the band closest to the combination switch. In the other cut you made, you will put the diode in with the band closest to the splice.

Electrically, it's like this:

COMBO SW.--------|

Not everyone lives in the cities and suburbs.

It means the beam selection is carried out by *grounding* the low or high beams, rather than by switching the feed to low or high beams.

Lower diagram in

DS

Most Japanese cars use ground-switched headlamp circuits, and have for decades. An increasing number of US and European vehicles are doing so, too.

It does not save any wiring.

In most cases the B+ is switched by the headlamp switch and the ground is switched by the beam selector ("dimmer") switch.

That is a big problem, and part of it comes from the use of the obsolete "driving lamps" name, which dates back to the 1920s when "driving beam" referred to the primary main headlamp beam used most of the time, and "passing beam" referred to the dipped/dim/low beam used on the occasion of passing another vehicle. That was valid terminology when passing another vehicle at night was a rare occurrence.

Nowtimes, the official name of the device in question is "auxiliary high beam lamp", which accurately denotes its function, but people are still going to be calling them "driving lamps" for a long time to come, and the problem with that is people too lazy and/or stupid and/or egotistical to educate themselves figure "I bought and paid for *DRIVING* lamps, and I'm

That's another problem!

Your link is dead.

Mike