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Car Forum / Honda Cars / February 200597 accord - low beam head lights don't work
They just stopped working. Bulbs are not blown, fuse under hood is good, even changed out with a new one to be sure. Bright lights work, brake lights work, everything is working fine. What do I need to check now? Help G > They just stopped working. Bulbs are not blown, fuse under hood is good, > even changed out with a new one to be sure. Bright lights work, brake > lights work, everything is working fine. What do I need to check now? Both sides are out, right? The following assumes that this is indeed true. I don't have the schematic for your car, but I'm pretty sure low beam does not go through a relay on an accord (unless someone could check that). It most likely goes directly through the headlight switch on your steering column. You will need a multimeter -- something that can measure DC voltage and resistance. Sears has a cheap one ($12) that will work just fine. Check to make sure you get 12V on either left or right low beam fuse by taking one of them out. Do whatever you need to do to turn the headlight on under normal circumstances.You should see 12V on one leg between one of these fuse connections and ground. If you don't, most likely your light switch (the one on your steering column) is bad or the wire from that switch to the fuse holders (both left and right) is bad. If you do see 12V, turn lights back off. Set the multimeter to ohms and check between the other leg of the fuse you were just on and ground (battery - will do fine). You should see continuity there (something in the order of ohms -- not KOhms or more) If you don't, you have a bad ground connection near the headlight. This case is unlikely, because your highbeams work. If I had to put money on this, I think your headlight switch is bad. Hope this is useful. Remco >>They just stopped working. Bulbs are not blown, fuse under hood is good, >>even changed out with a new one to be sure. Bright lights work, brake [quoted text clipped - 28 lines] > Hope this is useful. > Remco isnt there a separate fuse for the headlights under the dash as well? or no? > isnt there a separate fuse for the headlights under the dash as well? or no? Yup -- but that one is common to all lights (high and low beams). Since the high beams are working, that fuse must be ok. The other four fuses (left/right high/low) are in series with that one, I think -- don't have his accord schematic, but that is the way it looks on the one I have. In other words, I doubt if it is a fuse: Besides him having changed them already, what are the chances that both fuses for both left and right low beam blew at the same time. > Both sides are out, right? The following assumes that this is indeed true. > > I don't have the schematic for your car, but I'm pretty sure low beam does > not go through a relay on an accord (unless someone could check that). It > most likely goes directly through the headlight switch on your steering > column. Looking at a generic wiring diagram for the '94 - '97 generation, it seems both the low beams and the high beams have relays, both located in the under-hood fuse box. To the OP: Are you sure your high beams are still working? According to the wiring diagram, the high beam relay is connected in series with the low beam relay, so if the low beam relay should fail, you would loose both low and high beams (including the blue high beam indicator light in the instrument panel). I don't find any path in the wiring diagram that is shared between left and right low beam without also being shared with the high beams. both are out, correct and the high beam works the indicator light is on in the dash and they are working. Will let you know the outcome later today. I bet it's the switch at the steering column too. thanks for the advise everyone It may not seem to make sense, but I would suggest changing _one_ bulb before taking the column apart. While it is unlikely for both bulbs to fail at the same time, it is not impossible, especially if you have a failing voltage regulator. A voltage spike could cause the bulbs to fail. Bulbs are cheap and easy to replace. Dan (This account is not used for email.) > both are out, correct and the high beam works the indicator light is on in > the dash and they are working. Will let you know the outcome later today. > I bet it's the switch at the steering column too. > thanks for the advise everyone > both are out, correct and the high beam works the indicator light is > on in the dash and they are working. Will let you know the outcome > later today. I bet it's the switch at the steering column too. > thanks for the advise everyone On my Rover 216GSi, there is a 'dim dip' resistor which only affects the Dip side of the lighting.  SignatureGraham W http://www.gcw.org.uk/ PGM-FI page updated, Graphics Tutorial WIMBORNE http://www.wessex-astro-society.freeserve.co.uk/ Wessex Dorset UK Astro Society's Web pages, Info, Meeting Dates, Sites & Maps Change 'news' to 'sewn' in my Reply address to avoid my spam filter. Thanks, Randolph, for checking that. While I haven't worked on an Accord it a bit, I really should get an updated manual one day.. This fact does change the diagnostics some. On the common path, there must be a different non-shared high/low beam path, because if they were all the same all lights would go on: one would not have low or high beams. On an older car I had, the low and high beams would turn on when you pull back on the high beam switch - that's why they wired the relay in series. It most likely isn't really "series", but they wired it into an OR situation: switch low beams on OR pull back on the high beam flasher turns on low beams. See if high and low beam relays are the same type. If so, try to swap them and see if the problem moves: if now your low beams work and yet your high beams do not, clearly the relay must be bad. If the relays are different, see if you see a change from 0V to 12V on one leg of the low beam relay when you turn the lights on. You may need to probe around. Onother leg probably always has12V on it (depending on how they switched it). Report back here with your findings -- now that we have someone that has an updated schematic, you should be able to solve it. > On the common path, there must be a different non-shared high/low beam > path, because if they were all the same all lights would go on: one > would not have low or high beams. The lights are wired so that you can not have the high beams on without the low beams on also. Clearly you can have the low beams on by themselves. Specifically, the head light relay supplies current to both the high beam and the low beam bulbs. The low beams are always grounded, the high beams are grounded through a relay controlled by the dimmer switch. See http://www.geocities.com/ng_randolph/Accord/94-97_accord_lights.pdf So, if the high beams are working, a relay failure can not be the cause of low beams not working. What is left is broken wires, missing grounds or a failed head light switch. To the OP: You said the high beams *are* working; When the high beams are on, are the low beams on as well? If so, the switch is most likely the problem. If not, my guess is that both bulbs failed. > To the OP: You said the high beams *are* working; When the high beams > are on, are the low beams on as well? If so, the switch is most likely > the problem. If not, my guess is that both bulbs failed. I stand totally corrected and need coffee now to wash that crow and shoe down with :) This schematic is quite different from the one I have, but mine is much older. Agreed also on the relays -- if the high beams work by themselves, low beams should be on as well. It could still be the column switch. Measure the voltage on the light's connector. Weird if both are blown at the exact same time, but I guess they developed Mean Time Between Failure to an exact science so they can count on selling lamps from time to time ;) That ground connector from the low beam (black) could be something they put on a common connection somewhere so I'd trace that, should you not see 12V on the low beam connector. > They just stopped working. Bulbs are not blown, fuse under hood is good, > even changed out with a new one to be sure. Bright lights work, brake > lights work, everything is working fine. What do I need to check now? > > Help > G ---------------------- The hi- cut relay can get welded over time (what's your mileage??) At least we're talking about an American version. Throw in DRL, and the troubleshooting gets even wierder. My '95 Odyssey welded the relay and it was solved the second we changed it, HOWEVER, the lugs in the headlight lamp connectors can get loose from torqueing them on and off so many times, so keep an eye on that too. The hi-cut relay is above the brake pedal, attached to the firewall, in a '95 Ody. Accord is probably similar. The relay will probably be mounted in a rubber (sound) isolator. 'Curly' |
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