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Herd WebMaster
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USA
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Posted - 05/07/2007 :  11:01:57 AM  Show Profile  Visit Herd WebMaster's Homepage  Reply with Quote
Driving Lights Installation
By Greg Sullivan

I have recieved multiple requests from members asking how I wired my driving lights. I will try to explain it here.

I purchased the lights from Chief Auto for about $60. They are 35 watts each, in a black plastic round housing. They come with an "in-line" fuse which is very important.

I wanted my lights to have power whenever my ignition was on. I decided to tap into the electric window circuit for two reasons: 1) I did not want my driving lights on if I had my key in ACCessory mode, knowing that our windows do not operate in ACCessory mode. 2) I knew they used a Self Resetting Circuit Breaker with a relatively high amperage rating - - which must provide current for all 4 windows running at the same time. The pair of 35 watt lights should not draw more than 5 amps. (70 watts divided by 14 volts)

I located the SRCB in the fuse box on the left end of the dash board. I pulled it out and measured with my voltmeter which SRCB contact in the fuse box is the powered (battery) side (with ignition key ON) and which is the load side (no voltage). I connected the wire from my new lights to the load side of the SRCB. I stripped about a 1/4 inch of insulation off the wire and wrapped it around the flat contact on the SRCB which would plug into the load side of the socket. I do not recommend ever connecting any device to the battery side of a fuse or circuit breaker. Doing so will create a serious fire hazard!

The in-line fuse is only inches away from the fuse box to minimize the risk of a short circuit that is not protected by the in line fuse. The window circuit breaker would provide the final line of defense against an electrical fire.

Finally, I decided to have my new driving lights cycle off automatically whenever my headlights came on (as controlled by the twilight sentinel). So I bought a DPDT (double pole - double throw) relay with a 12 volt coil. I jumpered the relay so only half the current to the lights passes through each set of contacts - minimizing the wear (arcing) on the contacts. I grounded one side of the relay coil and connected the other side to the light in my ash tray. Of course, my ash tray light comes on whenever my headlights are on. It was a convenient place to connect the relay. Then I made an interesting discovery, if I dim the dash lights very low (which includes the ash tray) the relay will de-energise making my driving lights come on while my headlights are on. There were a few occasions where that "feature" came in handy.

I have had this setup over a year now with absolutely no problems of any kind. The circuit works exactly as I had intended.

If some part of this procedure was unclear, I would be happy to explain further (via direct e-mail).

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