Headlights wouldn't turn off for a month, now they won't turn on

Tiny
JEMUEL
  • MEMBER
  • 2001 SUBARU LEGACY
  • 2.5L
  • 4 CYL
  • AWD
  • AUTOMATIC
  • 155,000 MILES
So the headlights on my car have been constantly running for the past month. They would be on as long as the car was on. I would be able to switch between high and low beams, but never could actually turn them off. Last night, they would not turn on. The yellow part of the headlights works, but I cannot turn anything else on. When I switch to high beams, it shows up on the dashboard, but the lights don't actually turn on. I tried to check fuses, but it was dark so I couldn't really see. What would cause the headlights to be stuck in either the on or off position?
Friday, November 6th, 2015 AT 8:22 AM

10 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Try moving your combination switch to put high beams on if they come on it may be the switch. You can also get it scanned for codes as it may be your drl module bad which the headlights run through. Also see if fuse 8 &9 have power running through them with headlights on that will tell you that the relays are good.
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Friday, November 6th, 2015 AT 9:33 AM
Tiny
JEMUEL
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  • 6 POSTS
So I checked all the fuses, and all of them look good. While the car was running, I checked the voltage at both of the fuses for the headlights. The left measured 0.2V and the right one was much lower, below 0.1V. I switched the A/C relay with the right headlight relay, but the voltage was the same, and I know the A/C works. My car does not have a drl module. I performed the high beam test you suggested and nothing happened.
What else could be wrong? Only the yellow side headlights work properly.
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Friday, November 6th, 2015 AT 1:07 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Check items in pic for power if no power coming from greenwire then it may be a bad ignition switch or a problem in fuse box if nothing by relays. You may have corrosion in fuse box under hood so you would need dielectric compound on prongs of relay and may move them a tad for better contact.
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Saturday, November 7th, 2015 AT 6:25 AM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
By the way the drl module is daytime light module and that still can be the cause.
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Saturday, November 7th, 2015 AT 6:26 AM
Tiny
JEMUEL
  • MEMBER
  • 6 POSTS
I don't have fog lights or a drl on my car, so I don't have a fog light or drl relay. I checked the voltage across the female terminals in the fuse box and there was no voltage for them.
I checked the voltage across the right headlight relay and there was 12 to 14 volts in both pairs of terminals, and in the corresponding fuse. The left relay had only 12 volts in one pair of terminals, and no voltage across its corresponding fuse.
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Saturday, November 7th, 2015 AT 12:29 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
If no voltage across the fuse then it may be bad or fuse box is bad which in your case I think is the latter that the fuse box isn't transferring power to the fuses so headlights will work. This will need to be physically checked by a pro.
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Saturday, November 7th, 2015 AT 3:21 PM
Tiny
JEMUEL
  • MEMBER
  • 6 POSTS
What was the first option? I think you made a typo
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Saturday, November 7th, 2015 AT 5:27 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
The first option is fuse is bad like not making contact in fuse box. But I really think this is a fuse box problem
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Sunday, November 8th, 2015 AT 8:14 AM
Tiny
JEMUEL
  • MEMBER
  • 6 POSTS
So I changed the fuse box, but the lights still will not work. When I turn the lights on, it shows up on the dashboard, and even when I put the highbeams on, the signal on the dashboard shows the highbeams as being on, however nothing happens. Again, the yellow side lamps work, just not the main headlights.
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Monday, November 30th, 2015 AT 6:21 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
When you turn headlights on does power go to the fuse? Or fuse box? If not then it may be a multi function switch or the wires may be broken or chafed and shorting out. Is power going to the relays? It cold possibly be the headlight switch as well. Are you sure you don't have a drl module on this car our schematics show everyone of the legacys do. It's at center of dash. Have this scanned for codes.
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Tuesday, December 1st, 2015 AT 6:08 AM

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