[forrestoff]

So weird problem that no one else seems to have. Hope to god it's not RTFM related, but it's a big manual..

I have a 2007 Odyssey Touring with the automatic lights. They worked fine up until a month ago.

Problem/Symptom
When driving at night with the headlight selector switched to automatic mode, the headlights remain OFF while the cabin and NAV display lights dim properly.
When under the same condition, I move the headlight selector to manual-ON, the headlights work properly and the cabin and NAV also dim.
When in automatic mode in the day time, I can watch the cabin and NAV display dim while going through a tunnel, and then turn back to day-mode when exiting the tunnel. The headlights remain off.

Has anyone experienced this?

 

[John Clark]

That's going to be a tricky one. Below is a wiring diagram for the headlights.

http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=140889

It looks like the lights are controlled by the combination switch control unit which then sends the signal to the control block which turns on the headlight relays. Since the interior lights dim you can probably rule out the sunlight sensor in the dash. Since the headlights work manually you can rule out head light relays. My suspicion lies in the "control block" that is located in the underhood fuse box.

You might start with seeing if there are any codes. Place a jumper wire across the #4 and the #9 terminals on the OBDII data link connector (DLC) and see if any code or codes come up on the gauge display. There are several different DTC's for the headlight system.

 

[forrestoff]

Shoot! One more very important piece of information I forgot to add--can't believe I forgot to mention this:

The issue started just after I took the steering wheel off to replace the wiper switch that was broken. Not only did I have to disconnect the switches from the cable reel, but I actually purchased another steering wheel and transferred all the switches and wires from my old steering wheel (when it was working) to the new one.

Of course everything went back together fine, and it appears that the control unit is receiving word that the auto mode is selected.

I had to buy a new steering wheel becuase I read the torque spec wrong and over torqued the steering wheel nut on my original wheel, which caused it to rub against the steering column.

I think you're right though. It's sometihng in the control unit. I"ll see if i can pull the codes.

 

[John Clark]

If you look close, in "Auto" the headlight switch doesn't make contact with anything. That tells me that the system basically just defaults to auto if anything in the headlight switch goes open circuit. In order to turn them off the switch connects to pin B1. In auto it connects to nothing.

Much of this is controlled by the CAN bus so it's going to be a little complicated. Since you were in the steering wheel and column, and it started after that, I'd definitely be suspect of something there. Where did you get the wiper/washer switch? Was it an OEM switch? The switch contains the combination switch control unit and it's possible that is the problem.

 

[forrestoff]

Yeah--you're right. I think that's the problem. I purchased the switch off ebay and matched it based on the similarity of the looks of the interface. I'll look there and see if I cna get the rigth component. Thanks a lot for the help.

btw, do you know what the little ground-like triangles mean (with letters like "D" and "B") on the schematic? I assume these are switch power nets that are defined somewhere else in the schematic, but I'm not sure.

 

[John Clark]

Those are where the particular wire connects to another diagram. So, scroll to another diagram and find where the matching triangle is and you see where it ties in.