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Hello and thanks in advance for your help! I have a problem that I've researched on these forums and elsewhere but can't seem to solve.

The car: 2003 Honda Civic EX

The problem:
I have one (driver's side) low beam headlight that doesn't want to work. One day I noticed it was out, then it came back on after a couple of seconds, then went back out. It's stayed out for couple of months (never has come back on again) but, again, the high beams have always worked.

What I've tried:
Swapping/replacing the bulbs - the problem is NOT the bulb, passenger's side works with either bulb, it seems to be isolated to the right side

Replacing/swapping the relay/fuses - there's only one relay in the engine compartment fuse box. I've swapped in other relays and swapped the headlight fuses and, again, nothing

Combination Switch: Removed, cleaned all of the contacts, and reinstalled, still nothing

Ground Wire: Wires and all connections/harnesses appear to be clean and corrosion-free. In addition, if it was a grounding issue, wouldn't the high beams not work (cause they do)?

I'm sure someone is going to suggest taking a voltage tester to it,but I'm not entirely certain what readings I should be looking for or what order I should tests things in (fuse box, combination switch, headlight harness, etc.)

Again, thanks for your help. You guys are all heroes and have saved me thousands in repair costs over the years.

 
Rep Power: 228

You can cheat and run new wires from the working bulb to make it work. If so run in parallel, not series.


Secondly do you have day time running lights? If so, the issue could be with the DLR unit.

 
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Start at the bulb connectors.
Use the side that works as your example.

Make sure the bad side didn't get baked/overheated/melted

 
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I'll consider the work around if I can't find the direct problem. No daytime running lights, just good ol' stock.

 
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Great idea on using the other side. I'll use that as a guide.

What order would you advise that I go in? Bulb connector, then relay, then fuses? Where does the combination switch fit in and do I need to test it? Anything else in the electrical "line"?

 
Rep Power: 518

I'd start with a good wiring diagram of the system, a voltmeter or test light, and use those to make a plan.

As far as testing, I need to know what is missing before I can chase a cause. A basic item must have both a power and a ground in order to operate, and if you don't have any idea which one is missing then you're not gonna get much done.
A wiring diagram should show what (grounds/powers) would be found in the headlight connector....then see what is or isn't there....then backtrack.



Example wiring diagram (partial), from the miracles of google:






And http://www.justanswer.com/honda/3bea...-one-went.html


I can't tell you this is 100% exactly correct for your particular car....You'll have to check that yourself.

 
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Just now getting back to this project. I've tested all of the wires up the the bulb and they show current. It seems to be a problem with the bulb but I (again) tried the passenger side bulb in the drivers side and it won't turn on to low beams, only high beams. So the problem doesn't seem to be the wiring and it doesn't seem to be the bulb itself. The problem continues of it turning off then on while driving.

As a side note, the multimeter only shows a reading of 11.8ish for the voltage. Could that somehow be tied to the problem? Do you think I need a new battery (the current one's been in there for around 6 years)?

 
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I should add that it's not like the bulb flickers or turns on and off repetitively. It typically doesn't turn on at all but sometimes (about once every other week) it decides to turn on for the remainder of my drive. Though there was about a 1 month period in the middle where it worked constantly.

 
Rep Power: 307

Since the high beams work, set it on low beam then provide a grounding path for the low beam following the lower red lines ezone provided that say ground and see if bulb lights. Use a needle and an a 2 alligator clip jumper lead to provide ground path. Pierce the wire near connector at bulb and watch it.

 
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there is a low beam safety recall on that switch ,that states: low beam headlights may not work. get it replaced for free at the dealership along with your driver and passenger side airbag inflator

 
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I'll try the needle trick this afternoon - good thinking Craig. As for the recall, I took the car in hoping they would fix it under that recall and when I got it back they said they insulated the wire or added a heat shield or something of the like. I asked why they didn't replace the switch and they said that the recall stipulated that if the car has no evidence of melting or damage they don't need to replace it, only patch it up. I certainly wasn't going to let them take more money and do the job, hence why I'm trying to do it myself.

 
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Alright, tried the needle trick and there is no way that i can press a needle into that wire. I even tried several sizes of brand new ones and couldn't get it in there - bent every one of them. Instead I tried separately putting the high then the low beam terminals into the harness and connecting the ground of the bulb to the battery via the alligator clips previously referenced. The high and low beam work great this way but still don't work when the bulb is properly inserted into the harness with all three prongs in. Does that mean it's a problem with the ground wire?

To clarify using this diagram of the harness where A is the ground:
A
|

| |
B C

I plugged one terminal of the bulb into B, then grounded the bulb to the battery, and the high/low beams turned on. Then I plugged the other positive terminal of the bulb into C, then grounded to the battery, and that one worked for high/low beams as well.

 
Rep Power: 307

https://www.civicforums.com/forums/a...0&d=1267189121

You can see here the RED/WHT lines both come together before the headlight switch.

I think you have an open/intermittent between the bulb low beam at headlight, and the junction where they join up before switch.

 
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I would agree CraigW...now what to do about it. It seems I've exhausted all of the testing. Should I run a new wire going to the combo switch or should I run a wire to the passenger side to pull from the red/white wire there? I've never had to replace a wire before, only the harnesses and the like. Do you just splice into the wire where you think it's good and splice into the other red/white wire (at passenger headlight or the combo switch) or should you cut the old one out and solder/insulate in a new wire?

 
Rep Power: 307

I would tie in close to problem headlight and run it in to cabin, then tie into the single line leading to headlight switch low terminal (pin 6)

Use a long length of wire and test before running wires.

 
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I tried my best to get through the firewall and couldn't get a wire through there. After trying for over 2 hours, I decided to just run a wire from the red/white wire on the bad headlight to the red/white wire of the good headlight close to where they exit their respective bulb harnesses. Both headlights now work perfectly so I'd imagine it was indeed the problem Craig mentions. Thanks for your help!!!

 
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Well it's a few months later and now the passenger side has decided to do the same thing as the driver's side did before. The headlight turns on for high beams but not low beams and it's not the bulb as I swapped the left and right and the problem persists. The crazy thing is that the driver's side still works great despite fixing it by tapping into the passenger's side (see previous posts).

I don't have anywhere to reroute the wiring on the passenger's side since the driver's side was disconnected. Wire testing shows the exact same results as I previously had with the other side (everything shows power/ground). Any suggestions? I'm ready to sell the car than deal with this dumb wiring issue again. I'm convinced it's possessed since it went out yesterday (Halloween).

 
Rep Power: 307

Since your right side still works you still have the ground path you provided for it.... but, you have now lost the ground path for the left side.

Provide a temp ground to left side RED/WHT line and see if it comes on. And then trace open grounding line from problem bulb to the working (properly grounding) RED/WHT lead going into cabin.