One Headlight Out....Phuck!

[Mister.E]

Ok so im having this weird "all of the sudden" problem with my driver's side headlight (RHD).

anyways to make a long story short, the drivers side headlight wont come on.

checked the bulb...fine
checked the fuse...fine

after the basic checks i busted out the multimeter and noticed that i wasnt getting any voltage to the H4 plug. ok, at this point im like WTF. so from there i unplugged the H4 harness from the other plug behind the headlight that is wired into the main harness. no fucking voltage there either. so i went back further and measured across the 2 points on the top of the fuse in the engine bay fuse box, i was getting 12 volts there.

at this point im kinda wondering what the hell to do now. so i removed the battery, all the loom, and tape from the fuse box to the junction where the harness goes out to the fender and also splits to the passenger side headlight area. from the fuse box to that junction nothing looks fucked up, so i re-loomed and taped everything and moved on.

it appears that 2 of the 3 wires from the plug (red & green) go out into the harness running to the fender and the other wire (i think it was pink/black) runs over to the passenger side. i checked the fender harness which i know is notorious for getting rubbed through and everything looks fine. i tucked both harnesses a long time ago to ensure this kind of thing wouldnt happen.

if anyone has ever experienced any problem like this or has any insight as to what would be wrong, your help would be greatly appreciated...thanks

[MadMaverick]

Ok so im having this weird "all of the sudden" problem with my driver's side headlight (RHD).

anyways to make a long story short, the drivers side headlight wont come on.

checked the bulb...fine
checked the fuse...fine

after the basic checks i busted out the multimeter and noticed that i wasnt getting any voltage to the H4 plug. ok, at this point im like WTF. so from there i unplugged the H4 harness from the other plug behind the headlight that is wired into the main harness. no fucking voltage there either. so i went back further and measured across the 2 points on the top of the fuse in the engine bay fuse box, i was getting 12 volts there.

at this point im kinda wondering what the hell to do now. so i removed the battery, all the loom, and tape from the fuse box to the junction where the harness goes out to the fender and also splits to the passenger side headlight area. from the fuse box to that junction nothing looks fucked up, so i re-loomed and taped everything and moved on.

it appears that 2 of the 3 wires from the plug go out into the harness running to the fender and the other wire (i think it was pink/black) runs over to the passenger side. i checked the fender harness which i know is notorious for getting rubbed through and everything looks fine. i tucked both harnesses a long time ago to ensure this kind of thing wouldnt happen.

if anyone has ever experienced any problem like this or has any insight as to what would be wrong, your help would be greatly appreciated...thanks


Im going through the same shit in my S13, only power is somehow shorted to my right side turn signals. Im prolly gonna end up rewiring the whole mess since this car has always had headlight gremlins and Im going with a new headlight setup this year.

If this is an S13, check for power before and after the switch (it should be there since one headlight works). Then follow the harness from there.

GL

[Mister.E]

yeah its an S13. me and my friend are going to rip off the fender tomorrow and im going to go over that entire portion of the harness and see if i can find anything there. if that fails then i dont know what the hell to do

[g6civcx]

Check light switch.

[Mister.E]

as in the stalk itself? shit i never would have thought of that....

i know another dude tearing down his 180 tomorrow so ill see if he will let me borrow his.

thanks for the suggestion

[g6civcx]

as in the stalk itself? shit i never would have thought of that....

i know another dude tearing down his 180 tomorrow so ill see if he will let me borrow his.

thanks for the suggestion

99% of headlight problems come from the switch. Read the FSM. Take the switch out and run the multimeter across the pins that are supposed to be connected when the switch is activated.

You can buy a new switch or take your old one apart and clean the contacts.

Good luck.

[g6civcx]

Also, the reason S13 light switches go bad so often is because the factory draws 15A X 2 = 30A max, maybe 10-15A nominal, directly through the switch itself.

After years of use, the contacts get corroded due to exposure to the current.

Newer cars (S14) don't pull current directly through the headlight switch. Instead, they use the headlight switch to trigger a very low current flow to a headlight relay which is designed to handle the load.

[Mister.E]

that's good to know. i would have never thought that the switch could affect only one headlight

[g6civcx]

that's good to know. i would have never thought that the switch could affect only one headlight

That's because the wiring goes like this:

battery - 15A fuse - headlight switch - left headlight

battery - 15A fuse - headlight switch - right headlight


One of the pins is corroded. That's why one side isn't working. The wiring is separate from each other so one side has nothing to do with the other. They're separate wires.

[ZX88]

combination switch. search theres a write up for it.

[Mister.E]

well shit that would explain it....

[Mister.E]

combination switch. search theres a write up for it.

good shit, found it

http://zilvia.net/f/tech-talk/145000-combination-switch-fix-write-up.html

[OBEEWON]

Dang, this happened to my 14. Blew fuses trying to fix it. Fawk it blew me brainz out. Still no fixey. To cold. Me nipps hurt. Fix in spring.

[ixfxi]

you guys dont know that ALL OF THE HEADLIGHT POWER runs through that shitty switch?

hence the invention of relays, and why i tell people to run relay setups.

mike / clearcorners.com

[OBEEWON]

Is it the same on S14's or do they have a sexy stealth no fail mechanism hidden between the sexiness of the 14 aura?

[projectRDM]

S14s are the same, they run a high current switch too, though on Kouki models there's a relay to trigger the lowbeams on at all times.

[OBEEWON]

Sweet! Good look!

I miss driving my S...

[Mister.E]

ok here is a brief breakdown of how shit went today.

got to the shop and pulled out the switch. cleaned up the contact surfaces of the little relay switches and put it back in to test....FAIL

grabbed known good switch from friend who was tearing car apart and installed it....FAIL

so we put my switch back in since i had already taken off the little white cover. we then proceeded to take a multimeter and test the contacts while the headlight switch was on. on the working side we got a good 12VDC but on the bad side we got 0VDC; go figure, my fuckin luck...its not even the switch.

since there wasnt even power being delivered to the switch we moved on to the next and final course of action. so from there we proceeded to remove the fender and unravel the tape from the harness. i looked for a good 15 minutes and couldnt find anything that was obviously fucked up and just jumped out and said "FIX ME!" just as i was about to give up i grabbed the 2 wires that were the same color as those exiting the fuse box from the HL fuse position and looked them over again. one of them looked kinda funny so i pulled it closer to inspect and the fucker broke in half....ok WTF!

i inspected the broken ends of the wires and they were teal as if the copper had some how oxidized and had broken connection over time.

so after some solder, heat shrink, and a shitload of tape we soon had the harness tucked again and the fender back on. both headlights are now working. only shitty part of the situation was that we werent able to get the fender to line up as well as it had been previously, but i guess you win some and you lose some.

thanks to everyone for your suggestions it was a big help in my troubleshooting process.