Switching driving lights with high beams on an 03

I have an 03, and I am adding a set of Hella driving lights. In the past, I have used the positive out of the high beam to be one leg of a relay circuit, and provided ground with a switch for the other leg of the circuit. The relay carries the load, and with the switch I have the option of having the drivings on with the high beams, or off.



So my hood is up and I am attempting to do the same. However, I'm learning the headlights are not switched quite the same on our trucks.



Throwing this out there, who else has attempted this and how did you do it?



Thanks

 

And, I have 4 watt city bulbs that I want to hook up to the running luights. Arethey also controlled the same as the headlights?

 

The signal to the bulb is a pulsed signal, but you can wire up the signal wire to the relay with no problem. It works fine on my '03. I have been accused of having a light fetish, and this is one of the first mods I made to mine, due to the poor stock light. I later went a step further, and installed bi-xenons from The Retrofit Source. Now I have have great low beams too.



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03 headlight switch

The dash switch output is just a multiplexed signal to the Front Control Module (FCM). The FCM is located under the hood under the fuse/relay box. The FCM is an electronic switching computer that powers up each individuial circuit for the head lamps and tail lamps (along with most of the other electrical switched loads). The Brite Box is the best way to modify this in my opinion. I got mine from Geno's. The Brite Box connects in to the factory harness and uses a seperate battery feed to maintain the right current draw such that the FCM doesn't shut you down on excessive curent or give you a lights out indication when they are all working correctly. This said, I would think that as long as your only using the headlight circuit for the signal for the relay that the FCM would be fine with it. This would force you to tap in to the headlamp circuit behind the head lamps themselves since the power wires do to go to the switch in the cab any more. Ken Irwin

 

Thanks Kirwin, that is exactly what I was planning to do (and have done many times previously on other vehicles).

A couple have let me know that as long as I am using relays, the additional current to trip the relays shouldn't affect the Dodge computer. Not sure if I needed it, but I bought some diodes that I will use to isolate the power coming from the head lights to the relays. Just making sure no current can head from the relay to the bulb, showing less draw to the Dodge computer.

Going to work on it tonight. I will let everyone know the results!