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Syncing PIAA driving lights with high beams

1604 Views 2 Replies 3 Participants Last post by  dukey33
Hi everyone,

I have my first Subaru (a recent purchase from a friend who was the original buyer.) This is a 2004 Outback wagon. An impeccably clean and well cared for vehicle and I'm already in love with the car after driving through several heavy snowfalls this year. It's a blast to have a 5-speed manual again. :)

I purchased PIAA 520 Ion Driving lights for the long, dark northern highway roads in Michigan. I would like to have the PIAAs turn on with my high beams and found out that Subaru switches the negative which won't energize the PIAA light circuit.

Any thought on how to do this? I purchased a relay that would "de-energize" when the high beams turn on, that would in turn provide power to the PIAAs through the normally closed contacts. I'm hoping there is a cleaner way to accomplish this.

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Yes, I came across this when I wired up the 2010 for driving lights

I am not sure how the PIAA wiring harness is connected. I assume it has a signal wire from the positive side of the high beam lights and a signal wire to earth?

When I did my driving lights, I made up my own wiring harness. I had heavy duty wires connected to the battery terminals which went to the lights. The heavy duty positive wire was connected via a relay. I used a quick splice connectors to connect a signal wire from the positive wire on the high beam to the relay switch and also a quick splice connectors to connect a signal wire from the negative wire on the high beam. In this way the driving lights came on with the high beams.

A variation is to run one of the signal wires from the high beam into the cabin (and out again to the relay) via a switch on the drivers console to turn the driving lights on and off as well.

An alternate variation is to add a second relay in series to the first. Connect signal wires with quick splice connectors to the positive and negative wires of the fog lights. That way the fog light switch controls the driving lights and you do not need an extra switch in the cabin. If you have the fogs and the high beams on, the the driving lights will be on as well. If the fogs are off, the driving lights are off. If the high beams are off, the driving lights are off. I had both relays mounted on a metal plate on the 2010. The plate was mounted to the chassis by a vacant 6mm screw hole.
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Just use the high beam ground signal to complete the control circuit on a standard Bosch relay. That should work.
If you want additional control, you can switch the high side of the control circuit. That will allow you to turn off the aux lights and run just the high beams.
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