Why is only my passenger taillight out?

[Hotwatermusic]

My passenger side rear taillight is out--both parts, rear and side. Turn signal and brake lights work though. The bulb filament looks good though. What would cause just my passenger side rear tail light to be out? 1974 911
Thanks!

[86 911 Targa]

Originally Posted by Hotwatermusic

My passenger side rear taillight is out--both parts, rear and side. Turn signal and brake lights work though. The bulb filament looks good though. What would cause just my passenger side rear tail light to be out? 1974 911
Thanks!

Just a guess, but you may want to have a look at the 6 pin taillight connector
for corrosion & voltage check.

Good luck,

Gerry

pm me as needed.

[TimT]

Check the grounds

[autobonrun]

I would not try to determine if a bulb is good by looking at the filament.

You need a voltmeter and you need a wiring diagram. A bulb is cheap, buy a new one and try it. If its not the bulb start troubleshooting in an orderly manner. If the bulb is good either you don't have 12v at the socket or you've lost your return (ground). Check for 12v at the socket. If you don't have it, check for voltage from the fuse. If you have 12v, confirm the return wire has not come loose or corroded at the connector.

I'm guessing it's not the bulb. There's a low probability two go bad at the same time unless a short blew both simultaneously.

Again if you're going to do troubleshooting you've got to have a voltmeter and the correct wiring diagram for your MY car.

[Eagledriver]

I had a problem with my 86 once where one side of parking lights went out. I suspect it was a broken connection somewhere. My solution was to trace the wires with a wire diagram and jumper the bad side to the good side so both ran off the same circuit. Worked like a champ unless you wanted to use the parking feature where you light one side with the turn signal lever when the engine is off.

-Andy

[Hotwatermusic]

So I just checked and I'm not getting 12v to the socket on the rear passenger side tail light. But it's odd because the brake light--that runs through the same socket--does work. I attached some pictures here. To make this matter worse, my front fuse box is an absolute mess. It looks like something out of WWII. The PO installed an alarm, some ridiculous automatic turn-signal gadget, and a bunch of in-line fuses that don't make any sense. I have absolutely no idea where to even begin looking at the front fuses for this tail light. Any suggestions where to start? It's a 1974

[DRACO A5OG]

HWM,

Hope you are well Brother!

Okay, I see your brake light is working so it appears to be at the fuse panel. I say this because if it was the ground your brake light would not work.

Check the wires going up to the panel to see if any are loose or dropped out, if so you have found the culprit.

Just note wires going in from the top are the 12v in and the bottom outs are to the component/switches.

Jim

[Chuck.H]

How about a picture of the WWII fuse box?

Might be time to get a wiring diagram and start returning it to stock, removing said alarm...

Chuck.H
'89 TurboLookTarga, 342k miles

[Hotwatermusic]

Here's my fuse box. It's been like this since I bought the car several years ago. I took sort of an "ain't broke don't fix it" approach to it, even though I knew it was a clusterF of wires that I didn't need. The second picture...I don't even know, just a bunch of grounds with a thick piece of foam board underneath? This fuse box should be a whole new post in and of itself...

[Hotwatermusic]

Can anyone tell me what fuse I should be looking at for the passenger-side tail light? I can't find a wiring diagram for a 1974. I am still trying to diagnose why my PS tail light won't work. There must be either a fuse or ONE wire worn out, as all other lights in the tail cluster work.

[86 911 Targa]

Originally Posted by Hotwatermusic

Can anyone tell me what fuse I should be looking at for the passenger-side tail light? I can't find a wiring diagram for a 1974. I am still trying to diagnose why my PS tail light won't work. There must be either a fuse or ONE wire worn out, as all other lights in the tail cluster work.

This is nothing more than my 2nd guess.

Your fuse panel appears somewhat similar to our '86,
however, the three 8A (white fuses) should be 5A (yellow) fuses.

However, someone has played some serious "fingerpoken" on this panel!!!!

Here:







Rotate & check for voltage on both sides of this fuse.

Here are a few links:

http://www.2010.cannell.co.uk/manuals/manuals_porsche.html

https://www.google.com/search?sourceid=navclient&ie=UTF-8&rlz=1T4GGHP_enUS433US433&q=porsche+911+electrical+manuals

pm me as needed.

Good luck,

Gerry

[Hotwatermusic]

So I checked the wiring bundle at the rear light cluster and everything seems to be ok. No broken or exposed wires. The tail light socket is not getting 12v though when the lights are on. Brake lights work fine on both sides.
I checked the front fuse box and again don't see any broken wires. All fuses look good. I checked the voltages, but here's the main problem...I don't know what fuse is actually for the rear tail light. I looked at the one listed in the above diagram but it didn't match with my car exactly. Compounded by the fact I know NOTHING about the electrics on this car, I am completely lost on trying to figure out why my passenger side tail light doesn't work. Any further advice or tips would be much appreciated. Thanks guys...I know this isn't as sexy a topic as HP increase or a suspension refresh but I can't my car at night now for fear of getting pulled over...

[dshepp806]

As Gerry suggested: check the fuses on BOTH the input side, as well as output side...all of 'em....report back. If you've got 12 volts on one side, you should see the same on the other side of the fuse...


BEST

Doyle

[86911tlcab]

The Haynes maual shows a gray/red wire that should feed from the bottom of fuse 1. The lettering in the manual is so small amd looking at it through a magnifying glass.
Do you even see a gray/red wire coming from the front fuse panel (bottom part)?

I had a similar problem on a project car. I would start by taking off the 6 pin connector in the back right corner of the engine bay and get a voltmeter with a connectivity buzzer and start checking my wiring connectivity working back from the light socket, to the the female connector, then from the same pin on the male connector to the front fuse panel. you have remove the wire from the fuze panel in order to ensure it isnt getting connectivity from another source. then put a small piece of tape on each one and start determining what wires go to what. Then create your cars wiring diagram. sounds long and tedious...and it is...

you can start with the wires that go through to the rear. Just below the gas fill pipe, there is a hole where the wires from the front feed back to the rear of the car through the main harness. and it looks as if this circuit does that. in the back of your engine bay, right front section, the wires from the main harness come through and some go to the right (and the 6 pin connector and the some go the left over to the 14 pin connector (ands the 6 pin for the driver side light bucket). surely possible you have a single line with has broken in the middle someplace but you wont find it unless you start checking connectivity.

One way to verify the bulb works is is to run a good wire from the 12v source to the right pin on the female connector...at a min, can help you find out which one it is...

[86911tlcab]

The reason the right brake light works is it comes off a different fuse (fuse 11). It also runs from the fuse, to the switches on your brake system, then to the rear...

[86911tlcab]

My suggestion was not the bulb really...you can obviously swap that to verify it is working. But once you locate the right pin on the female connector, you can run 12 v to that pin and then start eliminating the light bucket as the problem.

The problem could very well be in the bucket itself. there are two metal pieces in the socket. One might not be pressing up against the back of the light bulb. take out the socket reach in there and make sure they are both touching the bulb. The back of the bucket can be removed to look at those also. Again, part of the suggestion to run a new wire to the correct pin and ensure the bulb lights up. hope that helps...

[Robin Reeve]

I am having a similar issue but I think it is my connectors on the back of the tail light housing. If I "push" the bulbs in deeper into the socket, they come on full. If i tap them, they go out. I thought I had a short or bad connection, now I am starting to think the connectors are just aged and need adjustment. My problem now is the screws that hold the housing into the car are a bit old and NOT cooperating.... I really dont want to drill them out...

[DRACO A5OG]

Robin, your situation is most like the pcb plate is fractured ans not allow proper contact. You need to get in the light assembly and repair it with a piece of plastic and glew it down.

Once fully broken the hot lead will touch the housing and it will cause havoc to your brake system and mayburniut yourbrake light switches in them mc. Ask me how I know :-(

[86911tlcab]

You can reach into the socket with a small tool and bend the two metal pieces toward you...I did the same thing and it worked fine. they will then press up against the light bulb..

[kidrock]

Originally Posted by 86911tlcab

You can reach into the socket with a small tool and bend the two metal pieces toward you...I did the same thing and it worked fine. they will then press up against the light bulb..

+1. I've also discovered that the soft metal contact at the bottom of the bulb often becomes flattened and creates issues similar to that described by the OP, even if the filaments are fine. Switch or replace bulb.