Taillights not working

Tiny
DAN RICE
  • MEMBER
  • 2002 SUBARU OUTBACK
  • 4 CYL
  • 4WD
  • AUTOMATIC
  • 160,000 MILES
Car listed above is a four door sedan. All exterior lights works inc. Reverse and amber also okay, but for all 4 taillights won't work. Bulbs and fuses okay. Visible connections appear okay.
Friday, February 14th, 2020 AT 12:29 PM

7 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,867 POSTS
Hi,

There are two fuses that need checked and a tail light relay. I attached a pic below of the wiring schematic. At the bottom of the pic, where I cut it off, you will see a wire I have highlighted. That goes to the rear driving lights.

In addition to just looking at the fuses, check to make sure there is power to them. Here are links you may find helpful:

https://www.2carpros.com/articles/how-a-car-fuse-works

https://www.2carpros.com/articles/how-to-check-a-car-fuse

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

https://www.2carpros.com/articles/how-to-use-a-voltmeter

https://www.2carpros.com/articles/how-to-check-wiring

When testing the relay, see if there is another relay in the box with the same part number. If there is, switch them to see if it makes a difference. If there isn't, here is a link that explains how to test a relay:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit
______________________________

The main fuse box is under the hood. See pic 2. The secondary is to the left of the steering column. See pic 3 The primary fuse in the pic below (20 amp at the top of the pic is in the main box under the hood. The other fuse is in vehicle.

Let me know what you find.

Joe

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Friday, February 14th, 2020 AT 1:43 PM
Tiny
DAN RICE
  • MEMBER
  • 4 POSTS
Thanks Guys, I found blown 10 A fuse in interior fuse box. Replaced it and turned on headlights at steering column location, fuse blew immediately. I removed all four (4) tail-lite bulbs and replaced fuse again. I did this to isolate which circuit may have fault. However, fuse blew again when I turned on headlights. I've checked all fuses in primary fuse box under hood. They're okay Relays? Ground Fault? Extra advice would be much appreciated. Thanks, gentleman.
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Friday, February 14th, 2020 AT 6:36 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Okay. We need to narrow this down. First, the fuse that is blowing is the one in pic 1. If you note, the fuse powers the front signals as well. Do the front clearance lights. Do they work when the fuse is blown? They shouldn't, but you mentioned all others work. Please confirm that for me. Also, confirm if the license plate lights are working. They, too, shouldn't be working.

Next, if you look at pic 2, you will see where the wiring color changes. There is a connector that joints the two different wires and then there are several splices in the power supply.
Any one of them could have caused a short if they came apart, but at this point that is doubtful. However, there is one thing that can be causing the issue. Does this vehicle have a factory trailer wiring connector? If you look in pic 2, you will see I circled the splices. Additionally, I circled the trailer wiring harness. If the vehicle has one, see if there is a connector you can take apart to the plug and then see if the fuse blows. It isn't uncommon for shorts to happen there.

Let me know what you find.

Joe
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Friday, February 14th, 2020 AT 8:16 PM
Tiny
DAN RICE
  • MEMBER
  • 4 POSTS
Hey Guys- Thanks again for additional info. Didn't know about the front turn and front clearance lights and the license plate light were on this fuse. Good to know, because the front clearance lights are part of headlight modules. Which I replaceable last week. This is when I noticed taillights were not working. I bought both headlight from JC Whitney. All I did was plug in headlight and clearance/parking wires into new module. Should I unplug the clearance lights and re-install new fuse? Again, to isolate the new headlight module like the 4 taillights? I really appreciate this advice. Dan (I'll check license lights right away.)
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Saturday, February 15th, 2020 AT 11:51 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,867 POSTS
I would disconnect it to see if the fuse blows. If it doesn't, I have a feeling that is the problem. I assume the old module was bad. If it wasn't, try it and see if things work.

Let me know.

Joe
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Saturday, February 15th, 2020 AT 7:10 PM
Tiny
DAN RICE
  • MEMBER
  • 4 POSTS
Again, gentlemen thanks so much for your ideas. They helped like you wouldn't believe ! Esp. The knowledge that this fuse serviced the front turn signals and clearance lights. I put my energy there because I changed out the headlight assembly and after 4 hours and 6 blown fuses I found the problem! A plastic on the right headlight was defective; a solid ground fault. This piece interfaces between the wire terminal and the bulb base. I took the same piece from the old headlight and bingo. The fuse held ! I took several hours to locate this defect so I had two beers; one for each of us. Thanks again. Great help !
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Sunday, February 16th, 2020 AT 11:21 AM
Tiny
JACOBANDNICKOLAS
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Good job. I'm glad you found it. Don't laugh, but when these types of problems come up, I have actually checked for the problem in the dark. LOL If there is a short, usually there is a spark.

Regardless, I'm glad it's working again and I enjoyed the beer.

Take care of yourself and let us know if you need anything in the futhre.

Joe
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Sunday, February 16th, 2020 AT 7:07 PM

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