Hello All,
I've been digging into this and not finding my solution, thought I'd check here.
So first, one of my low beams was out. The fuses (in the cockpit and under the hood) were all fine, and the bulb was good. After driving with only one headlight for a month or so, the other one went out the other day. Once again, all the fuses and bulbs get continuity. However, when checking for voltage at the cockpit fuse harness, I'm only getting about 6.85V. To my knowledge this is the first stop for the current after the switch, right? Is it possible that the switch has gone bad? The fog lights and high beams all work.
If any of this makes sense to anyone, please do share whatever you can. I'm at a loss.
Thanks in advance!

 

left and right Low beam power comes thru shunt 20/27 in position CSH4, then thru relay 2/62 in position CMI7, both on the CEM, then two fuses 17 and 18 under the hood. Easiest to simply swap shunts and relays (if same part number) to test them. It's not your switch - (unless it was physically broken usually with someones knee entering the car) By the way the switch is actually a "light control module". if you remove it there's only a few wires - not enough for all the functions in the switch. The "switch" is part of the CEM.

 

Thank you for the info and the diagrams. Unfortunately, I did as directed and still no luck. I swapped shunts, and I swapped the low and high beam relays and the lows continued not to work while the highs continued to work. So it seems that is not the problem.

I've read that dirty CEM contacts could cause funny things to go wrong... is that maybe a next step? Pull the whole board and clean it with contact cleaner?

And last, according to my reading of the above schematic, the fuse by the driver door is before the CEM, and I'm not getting any voltage there, so is it possible that the issue is somewhere else? If not the switch, then I don't know... maybe I'm in over my head and it's time to go to a mechanic.

Thanks for all help and patience as I try to figure this out.

 

You don't have 12v at the #1 fuse in the c fusebox (on end of dashboard) but have power at #2 fuse? #1 and 2 fuses (for low beam shunt and high beam relay) are fed from the same 30+ source. Do you have a melted connection where the shunt plugs in? (have seen that a couple of times.)
If you have 12v at #2 but not #1 fuse the fusebox simply pops out to be able to check the back side of it.

 

I have nothing at fuse #1 and 20 something volts at fuse #2 when the high beams are on...

I'll pull the fuse box in a bit and see what's going on there.

 

????? There should be battery voltage at both fuses. 12-14v, not 20. (you have a 12v battery) And #2 fuse (and #1) should have power with or without the high beams on. You are certain this is a 2004? What's the date of manufacture? The 2005 uses different fuses, as in there are no low beam fuses and the high beam fuses are on the CEM - And the CEM is a totally different design. Those cars that have an internal "circuit breaker" in the CEM - that can require a reset by reading and erasing stored CEM codes, to restore power to the protected circuit. In this case your low beams.

Have you scanned the CEM for codes?

 

Yes, it's been more than two years ago, but have you sorted out the issue? I'm having the same issue, first one side not working, then the other one as well, and also reading only 6,8V or so on the fuse.

Read so many thread on low beam issues, so really hope you have an answer!

Thanks,
Matthias from Holland