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Discussion Starter #1
Hello - I have an odd problem. Both my tail lights failed about a month ago (all other lights were fine). I checked the brake lights and they worked (I know this is the same bulb). I replaced both bulbs but did notice that there was no filament damage in the old bulbs. Previously when lights have gone out and I replace them I notice filament damage which indicates a cause of failure. Anyways I replaced with new bulbs and both tail lights started working again. I had no real explanation but was just happy they were working again. Then a few days ago (around 1 to 2 months after replacing the tail light bulbs) they both went out again (brake lights still worked)! It can't be a coincidence that they both go out at the same time. Also it does not look like there is any filament damage. I have a feeling if I replace them again they will work for a few months then both fail. I read through the posts and tried to flip the parking light switch back and forth on top of the steering column, each time checking to see if the tail lights will go on. They never did. All the other lights seem to be working, just the tail lights do not.

I was thinking possibly a fuse (I had replaced the one for the cigarette lighter previously), however if it was a fuse then the tail lights would not work even with new bulbs....

Any suggestions?
 

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Perhaps you have a poor connection to the taillights causing fluxuating voltage. This is a SURE way to burn out incandescent bulbs. Do not forget that a poor connection could be EITHER the power or the ground to the taillights.
 

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was thinking possibly a fuse (I had replaced the one for the cigarette lighter previously), however if it was a fuse then the tail lights would not work even with new bulbs...
Also, not a fuse if the license plate lights, and the clearance lights at the front corners, are working. It's all the same circuit.

All the other lights seem to be working
All?

In each rear combination light housing (the red and amber housing at the outer corners of the rear fenders) there's two lights that work together; there's the tail/brake light bulb (larger triangular section in photo below), and a marker light on the side (horizontal lens). (The turn signal is in the amber area below.)

IMG_4299.JPG

The tail and marker bulbs are wired together in a short harness at the housing. When the clearance and tail lights are switched on (e.g., using the switch on top of the steering column), and the rear tail light in each housing is lit, the side marker should be on as well.

In your case, when the tail light isn't working (either or both sides), is the side marker in that same housing working, or not working?

It's very odd that only the tail light bulbs stop working on both sides. Although connected to the same primary power source, they are on separate branches at the back of the car (obviously, left and right sides). They do share a ground, but that same ground is also used by the side marker bulbs and the license plate bulbs. So if all the other bulbs work properly, then "common" elements are less likely the cause because that should affect the other lights as well.

What brand and type (number) replacement bulbs are being used?
 

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2005 Outback Wagon 3.0 L.L. Bean
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Spend the extra $2.50? for higher quality bulbs. Find some bulbs whose #s end in "LL". Avoid touching the glass on the bulb. Not as important as headlamp bulbs but good practice. Make sure bulb sockets are corrosion free.
 

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2008 OB Limited 2.5i, Portland OR USA
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OP said he had no filament damage on the replaced bulbs for both bulb changes and for both sides. This is four-out-of-four occurrence rate - and it likely indicates a contact problem in the base of the bulb sockets.

Was there moisture inside the plastic housings by any chance?

Clean up the contacts in the bottom with a clean pencil eraser, or perhaps some 400 grit emory paper, get rid of any moisture and its source, and the problem should be solved.
 

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I believe the 2005 tail/brake bulb is a 7443 or similar. The rectangular sockets for those bulbs have substantial contacts, but certainly a close inspection, and cleaning to the extent possible, is a good idea.
474004
474006


Also, wonder if the combination light housings, and the short wiring harness to them, are original, or was the car repaired at some time with replacement/aftermarket parts. (http://opposedforces.com/parts/legacy/us_b13/type_18/electronic/lamp_rear/illustration_1/ )
 

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Discussion Starter #7
Thanks for everyone's reply, it is greatly appreciated. Yesterday I went out and bought replacement bulbs from SYLVANIA Silverstar 7443. The guy at the parts store offered me two options, the cheap ones or the better ones, I chose the better ones and paid the premium. I will let everyone know how long they last.

To my knowledge the wiring is original.
 

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2006 OutBean, 2005 LGTW
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I had a tail light/brake light out on my 05 LGT. I went and popped in LED's and surprise surprise, light was still out.

Ended up being the ground connection in the plug but it could have been any connection in the plug. I couldn't figure out how I could get voltage at the plug with my voltmeter, but the light wasn't working. Swapping the bulbs around did nothing--the one bulb that was "out" worked on the other side. I bent the ground out with a small pick and viola--connection made.

I'd look for voltage at the plug first. If there's voltage, the problem is in how the plug is connecting to the bulb. Bend out all those tabs so you make a solid connection.
 

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2017 2.5 Outback Limited no Eyesight
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114 Posts
I had a tail light/brake light out on my 05 LGT. I went and popped in LED's and surprise surprise, light was still out.

Ended up being the ground connection in the plug but it could have been any connection in the plug. I couldn't figure out how I could get voltage at the plug with my voltmeter, but the light wasn't working. Swapping the bulbs around did nothing--the one bulb that was "out" worked on the other side. I bent the ground out with a small pick and viola--connection made.

I'd look for voltage at the plug first. If there's voltage, the problem is in how the plug is connecting to the bulb. Bend out all those tabs so you make a solid connection.
 

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2017 2.5 Outback Limited no Eyesight
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114 Posts
Get yourself some Deoxit. It cleans the connection and also removes any corrosion and improves metal to metal contact. If you're old enough, you would remember the old televisions needed to have their channel selectors sprayed under the knob with this occasionally to keep a clean TV signal. This is the same stuff. It works well.
 

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2008 OB Limited 2.5i, Portland OR USA
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Another thought here: I've seem a few bulb base sockets of this type that have a badly-toleranced glass plug in tab. The bulb's contact bars lay on top of this glass tab, and there is little compliance in these kind of contacting systems. A single bulb that is over-tolerance can cause the contacts in the socket to be over-bent or flattened out. That bulb will tolerate the situation OK, but a replacement bulb put in later may be a loose fit and have erratic operation. There will also be less heat transfer out of the bulb base afterward, shortening the life of bulbs - heat is the enemy here, of course.

This may have been the cause of the socket issues that aesthetic.rake experienced as well.

So check the "springiness" of the socket's contact bars, as well as cleaning them up in general and using the Deoxit that @dmac3 suggested.
 
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