Just picked up a nice low-miles '07 EX V6 5AT last month. While I was examining and test-driving it, I noticed that the full headlamps came on whenever the ignition was switched on (even though the headlamp switch was off) and went off whenever the ignition was switched off. Not the DRLs, I mean the full headlamps, high or low beam depending on the beam selector position—including the parking lamps, tail lights, side markers, license plate light, and the green lights-on indicator on the dashboard. With the ignition on, engine running or not, handbrake applied or released, operating the headlamp switch did nothing and it was not possible to have the headlamps off or to have just the parking/tail lights on without the headlamps. The DRLs likewise were out of the question, no matter what combination or sequence of events (start engine, release handbrake, etc). The only available options were:

• All lamps off (only with ignition switched off)
• All lamps on (immediately with ignition switch-on, or could be had with the headlamp switch if ignition was off).

Sometime during about a 16-mile stretch of driving, that condition went away and everything started working normally: No lights at all until the engine is started and the handbrake released, then the DRLs come on, and that's all that comes on unless/until I manually turn the headlamp switch on. None of this depends on how bright or dark it is outside (which stands to reason, because this car isn't supposed to have automatic headlamps that detect ambient light levels).

That lasted until last week; now the problem's back. I don't think it's a faulty headlamp switch; the headlamp switch works normally when the ignition is off. But with the headlamp switch off, switching the ignition on or off immediately/simultaneously turns on or off the full headlamps +tails, parking lights, license plate light, dims the dashboard, little green lights-on indicator lights up. I can pick low or high beam, but I cannot switch off the headlamps.

(If I have the ignition on and then turn the headlamp switch on, nothing changes because the headlamps are already on, but then the headlamps remain lit after I switch off the ignition, which is the normal waypath lighting feature apparently working correctly).

I don't know a lot about this circuit, but I guess I should be suspecting the "multifunction switch control module" (built into the wiper switch) and/or the MICU. Anyone got further thoughts...?

Thanks.

 

Do you have the pdf version of the shop manual?

 

Thanks, I do have a PDF service manual I downloaded from I-forget-where. It's 7,372 pages, but it seems potentially incomplete (though perhaps this is how Honda service manuals are; this is my first Honda). Is there a better/more complete one available somewhere? And in case this what I have is adequate, what would you direct me to?

 

Not sure what is included in your manual. The manual I have is about 3000 pages and has quite a bit of information.

I suggest purchasing one from automanualsource.com for your car. It runs around $22 and is worth the investment. It will show you how the wiring and control units are setup.

There is also a B-CAN test without HDS in there. Your manual may have that information too. That is probably where I would start.

 

Hey, thanks. There's really not much info in the manual I already have; I think it's a bootleg of a bootleg. Guess it's worth what I paid for it ($0). The one you linked covers '03-'06, but AFAIK there weren't a lot of changes for '07, so I should be OK with the '03-'06 manual, do you agree?

Since I've got your ear (eyes): D'you think this and/or this would be a wise purchase?

Thanks again.

 

I have something similar to the inexpensive item. It does a good job of reading/resetting codes and some live data.

I don't know what capabilities the more expensive item for your car. I'd do some research before considering purchasing, because the cheaper item may be all you need.

 

Thanks kindly.

 

Purchase made, manual downloaded…er…yep, this is a whole lot better than the crummy one I downloaded before. Thanks. Now just have to spend some time wrapping my head around the Dx procedures. This is not only my first Honda, it's also my first car with OBD2. The newest of my previous cars was a '92 model, so I've got a learning curve to slog through!

 

Update: the steering column and dash covers are easy to remove, now I've got the manual that points at the hidden screws and clips (Thanks, PAhonda). Lookit there, a couple of white wires attached to the headlamp/multifunction switch connector. H'mmm, where do those go? Off come the dash covers...someone zip-tied a blue plastic Hella relay under the dash. Two white wires to the column, one white wire to the fusebox. Open fusebox, find wire crammed onto unused fuse slot. Okeh, clearly the aforementioned dillweed put this in so the car would have auto-on full lights with ignition on. Doesn't explain why the behaviour was intermittent, but that's probably because those blue plastic Hella relays aren't very reliable. I yanked the whole of it out and put the dash back together, now everything's working normally. Next up: replace automatic gearshift light. Had a practice run (Sylvania bulb I bought was so poorly made that it doesn't fit), will do it again with a better bulb when I get a few minutes.

 

Thanks for the update, sounds like you got it worked out.