Well, I have cuts and scratches all over my hands and I still cannot diagnose this problem with the low/high beam headlights (not the Xenon HID):

When the headlight selector is:
1st position - OFF, or
2nd positon - AUTO with sunlight, or
3rd position - Park/Dimmed running lights
the headlights should be on a dipped/dim setting (remember in Canada, all cars have a daylight setting for headlights). In the US, the headlights would be off. However, what I get is left headlight on high beam and the right one fully off. Now get this, it doesn't happen all the time, but it is happening more and more and has only appeared this year. I have swapped bulbs and the problem does not follow the bulbs. I even swapped the ballasts (although that should be for the Xenon bulbs) and that also did not change anything. When I put the headlight switch to High beam (or pull the switch lever to me), the high beams go on for both lights.

So I suspect that I have a control or wiring problem, but I am not sure what to do from here. Any suggestions would be most welcome. Is there a way to disconnect the Canadian running light option?

Thanks,
Jeff

It could be the factory module that is problematic. I understand that Hamsar is the company that makes the DRL module, try sending them an email for assistance? If they are able to help could you please post a reply here with the cure?

Thanks!

Well, thanks for the suggestions and to this forum. I found and fixed the problem!!!

First off, I located the service manual for my car on this site which was invaluable for understanding the workings of the DRL
http://www.nicoclub.com/FSM/G35/Sedan/2004/

This, along with the comment above, helped me zero in on the likely culprit - the "Daytime Light Control Unit" (and to find it in the engine compartment).

A couple of taps on the unit caused the headlights to flicker, so that's got to be a good sign that the problem is there.

A call to the local stealer - $270 for a replacement. Ouch. A call to the local auto wreckers - no G35's. So back to the internet and search for Daytime Light Control Unit and there are a whole load of posts on the Nissan forums about the unit and cracked solder connections, and that it is not too difficult to find and repair. So I did ....

Here are a series of photos that show the steps. The research took 4 days, the repair took about 30 minutes.

Jeff

Here is the location of the unit in the engine compartment


A little closer after removing it (easy)


Now for the fun part - open it up. There are 4 small plastic tabs that can be moved with a small screw driver,



Here are the insides - pretty simple for $270!!!


And the backside with all the soldering. See the suspicious area?


And zooming in .... Yup, that is a cracked solder connection. I applied some more solder with a soldering iron, and it's good as new. Reassembled everything and put it back in the car. Yes!!!

Excellent!!! Great use of resources and troubleshooting

I do believe that is the unit Hamsar supplied to Infiniti. Glad you have things working and saved a couple hundred bux.

NICE work!!