Doddy

My passenger side headlight went out so I checked it and the bulb was still good. Then I checked the fuse and it was still good so I tried a new bulb anyway and no luck.

I pulled the fuse on the driver side and checked to see if there was power running to it and ib got a voltage reading. When I checked the fuse for the passenger side there was no voltage reading.

Does anyone have any idea why I'm not getting any power to the fuse box? The brights work which I know are on a seperate switch but I know power is getting there.

Thanks.

nvtoyota

actualy power may not be getting to the low beam side usualy there are 3 wires that go to the head light 1 hi 2low 3 ground and somtimes the wire will short to the ground and not have any power where you think it should basicly it could be a spot where the wire has rubed bare inbetween the fuse box and the light itself just an idea

Doddy

I thought about that but, wouldn't that blow the fuse if it grounded out?

4Crawler

iTrader: (3)

Actually, the wires are common-12 volts and then high and low which connect to ground when that light is turned on (assuming a non-DRL setup). You can find out which by testing voltage at the headlight socket:
- http://www.4crawler.com/4x4/CheapTri...ml#VoltageTest

And that will also help you identify where the problem might be, that is is it in the common side or the low-beam side of the circuit.

TheDurk

There are two different wiring set-ups depending on whether you have DRL's or not. It really helps to have your vehicle info in your signature when you ask questions.

As far as I can tell, power to the left and right fuses comes from the same source within the box. I can't see any way, other than a fault in the box, that left would get power and right would not (before the fuse in both cases). Are you sure you are checking the correct side of the fuse? If so, time to open up the box and trace the circuits with an ohmmeter, looking for damage.

w/o DRL

w/ DRL

TheDurk

The DRL circuit is switched power, common ground. (2000+) The non-DRL (1999- ) circuit is switched ground, common power as you describe. I think this is indeed what he has, but it would help for the OP to confirm as the troubleshooting is totally different.

If both brights are working on a non-DRL circuit, there is NO WAY there is a power interruption in the fuse box as he describes. The problem has to be between the bulb and ground--or, more precisely, between the right bulb lo side and where the two ground wires from both lo sides come together in the main engine harness. Or am I missing something?

Doddy

Its a 2000 sr5 w/ daytime running lights...sure hope Its not a problem with the fuse box.

Doddy

It really helps to have your vehicle info in your signature when you ask a question.

w/o DRL

w/ DRL[/QUOTE]

I usually have my info in my signature but I'm on my cell phone so I guess it's not showing up.

TheDurk

It's probably not. So switched power, four fuses, common ground.

OK, back to square one, then. The DRL has separate hi and lo fuses for each side so the brights have no effect on the lows. Check those fuses again, all four just for fun, then check for 12V+ at the bulb connector on the passenger side on lo beam. Note: those fuses will only power up as hi and lo are switched on or off. I'm thinking you either checked the wrong fuse or checked with the hi-lo in the wrong position. Let's hope so.

Do both DRL's work?

bigd9247

Also, try pulling the fuses and testing for voltage at the actual fuse terminals. Make sure the terminals are clean and free from rust and corrosion. I've run across fuses that weren't making a solid connection before and fuses where the wire had corroded and rusted off from inside the connector to the fuse. In both cases, the fuse was fine, but voltage wasn't being transfered across the fuse to reach the head lights. On an older Toyota I used to own, the wires corroded and broke off inside the actual bulb socket but they broke when I pulled the socket off to change the bulb. Like everyone else has said, it's time to just start testing with a multimeter. Start by tracing the wires back from the bulb socket until you find the problem... most likely it's somewhere between the fuse box and the bulb socket.

Doddy

I checked the coreect fuse but there was no power runing through the passenger side. I'll have to try it all again tomorrow when I can acyually see what's going on.

Doddy

Looks like the spare bulb I had in my car was bad along with the one I bought a month ago. Pulled the driver side bulb and through it in and it worked. I'm an idiot I should of just done that first. Thanks for the help guys.

hrt4me

I have a 1996 4Runner SR5, and my passenger headlight is also not working; the bulb is good (works on the driver's side), and when I twist the headlight turn signal lever knob to position 1, both parking and side marker lights function; in position 2, those lights also function, as well as the left/driver's side headlight (low and high beam, and high beam indicator in dash works properly) - but the right/passenger's side headlight 9003/H4 bulb only emits a dull glow like a candle or a lit cigarette (on both low and high beam)...

so can anybody offer suggestions on how I can diagnose and fix this?

4Crawler

iTrader: (3)

Check the voltages at the back of the headlight bulb connector:
- http://www.4crawler.com/4x4/CheapTri...ml#VoltageTest



Sounds like you may have a bad common terminal connection. When that happens both the low and high beam filaments are in series and that cuts the current way down and makes the light output very low. Either that or there is the wrong bulb in there if it has never worked properly. Easy double check is to swap the bulbs side to side and if the problem follows the bulb, bad bulb, otherwise check the wiring or maybe the passenger side headlight fuse is bad.

hrt4me

the bulb is fine, as it works in the left driver's side

how would I diagnose, and more importantly, fix a "bad common terminal connection" where the low- and high beam filaments are in series, cutting down the current and making the light output very low?

I'll also check the fuses tonight...

4Crawler

iTrader: (3)

You would diagnose that problem as noted in the page I posted above:
- http://www.4crawler.com/4x4/CheapTri...ml#VoltageTest

You *should* measure 12-13 volts from common to low or common to high terminals on the back of the bulb connector. But if you are only getting like 6 volts across both filaments, then that says the common terminal is not connected. Or you could measure from the battery + terminal to the common terminal. If all is OK, you should see nearly 0 volts between the two (the common terminal should have 12 volts as does the battery, so 12 - 12 = 0). If the common terminal voltage is bad, figure out why. Check at the fuse, if the voltage is good there, then the wire between the fuse and the bulb is bad. If the voltage at the fuse is bad, either the fuse is damaged (they can oxidize and reduce current flow without popping all the way open). Basically you want to measure voltages at a given point and decide if that is OK or not. If OK, then move closer to the light and re-measure and if not OK, move closer to the battery and re-check: