Tail lights not working?

mickey356 · 01-12-2016, 02:23 PM

I've got dash, brake, headlights and turn signals all working, but no tail lights.
Where do I look first?
1968 912
Thanks

bivenator · 01-12-2016, 02:33 PM

The pressure sensing switch on the master cylinder has most likely gone bad. Easy fix, do a search and your questions will be answered.

afterburn 549 · 01-12-2016, 02:34 PM

Go give all your fuses a twist.
Ck for continuity too .

Hoss911sc · Hoss911sc's Garage

I suggest starting simple and checking that both bulbs are making contact for the tail light and brake light function. Easy to do. If the bulbs are at all loose it can cause the issue you are describing. The contacts in the socket can be less than tight due to a weak design(IMHO). I had the same issue and assumed the switch on the master cylinder was the issue but checked the bulbs first and they were moving in the poorly designed socket. If the bulbs and contacts are fine, then the switch would be the next potential culprit. I had to use a fix I found here on the board of adding solder to the 2 bulb contacts and then filing back for a tight, solid fit. Fixed my problem. Good Luck

timmy2 · timmy2's Garage

Check the wiring at the fuses up front. Fuses are good if your front running lamps are on. The front and rear running light wires are doubled up on the same terminal.
After that it could be loose sockets. Also try wiggling the 6 pin socket by the rear motor mounts n each side.

grant lyon · grant lyon's Garage

+1 check bulbs/socket are clean. Just went thru this, with front turn signal flashing but nothing on rears. Easy 1st check is to remove lens and wiggle bulbs with emergency flashers on.

Amstaff · Amstaff's Garage

I would also check the micro switch at the brake pedal. Make sure there is power going to it which would verify that all fuses are good.

mickey356 · 01-13-2016, 09:08 AM

I checked the bulbs, they seem to be seated properly. Didn't get to the brake light switch yet....it's freezing out!!!!
Just put a new master cylinder in a week ago.
Fuses and wiring at fuse box look good.
Couldn't find a 6 pin socket anywhere near motor mounts?

timmy2 · timmy2's Garage

No 6 pin sockets on your 68, sorry, I read a different year in your signature.

mickey356 · 01-15-2016, 09:28 PM

Out of curiosity, what does the brake light switch have to do with tail lights? Is it a 2 phase bulb?
And in doing research I see two kinds of switches, one on the pedal cluster, that I do not recall seeing on my car before I put the floor boards back in, and another on the master cylinder. Does a 68 swb have both? There is very little info out there on this stuff, or I'm searching the wrong thing. Thanks

mickey356 · 01-16-2016, 09:43 AM

Ok, I'm way out of my league here. Obviously this car has been through the ringer over the years and it's been hacked up and rigged. I took the floor board off this morning hoping to find a loose wire on the switch.... Above is what I found, ...lots of unconnected wires. Some in the back too.
I have no idea where any of this stuff is supposed to be hooked up.
All fuses are ok, dash lights work, head lights work, turn signals work, brake lights work.
Rear tail lights are out. Front running lights are out.
Also, somewhere in its life, the windshield washer system was yanked, and there is NO emergency flasher switch (and of course those are like finding hens teeth).
Thanks in advance for any help you can offer.

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mickey356 · 01-17-2016, 07:52 AM

Anyone? Bueller.....
Is it that bad? You're afraid to tell me it's terminal?
Was it something I said? I'm so insecure!!! Someone say something!!!!

ossiblue · 08:17 AM

Quote:

Originally Posted by mickey356

Ok, I'm way out of my league here. Obviously this car has been through the ringer over the years and it's been hacked up and rigged. I took the floor board off this morning hoping to find a loose wire on the switch.... Above is what I found, ...lots of unconnected wires. Some in the back too.
I have no idea where any of this stuff is supposed to be hooked up.
All fuses are ok, dash lights work, head lights work, turn signals work, brake lights work.
Rear tail lights are out. Front running lights are out.
Also, somewhere in its life, the windshield washer system was yanked, and there is NO emergency flasher switch (and of course those are like finding hens teeth).
Thanks in advance for any help you can offer.

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First of all, don't panic. Many have had the same experience with hacked wiring and sooner or later, things will come together.

Ignore the posts about your brake lights or brake switches as they are not related to the running lights. Even though you have a dual element bulb, the wires to that bulb that power the running lights is not related to the brake light switch.

Note the bold in your post, that gives you some clues. Dash lights work but are not on fuses. Headlights work so those fuses are good. Brake lights work and turn signal lights work so that fuse is good as is the brake light switch. The only circuit that is not working is for the running lights--fuses 7 and 8--but how do you know the fuse for the running lights is good? You did not make that clear. Visual checks are not adequate.

You need to start testing, using a test light. Start by turning on the light switch and checking both sides of the fuse at terminals 7 and 8. Do you get a light on both sides of the fuse?

At this point, I'd suggest you perform the above check and report back. Electrical issues, especially, require a lot of feedback so we'll wait until we know what you're dealing with.

One step at a time.

Oh yeah, all the above advice is moot if your wiring has been seriously hacked so lots of good clear pictures may be necessary. Be prepared.

Refer to this wiring diagram for your '68

http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_1965.jpg

mickey356 · 01-17-2016, 10:03 AM

Thanks Ossi!
Ill test and I'll report back later today or tomorrow.

mickey356 · 01-18-2016, 10:54 AM

Ok, so it was late, dark and REALLY cold last night but I hooked up the tester ground clip to the battery neg, turned the key on and touched the brass terminals on both sides of the fuses...nothing.checked a few other random fuses and contacts....nothing. Thought maybe the tester was shot so I touched the pos on the battery and it lit up so it's working. Thought maybe, (why, I have o idea) that the car needed to be running so I got it to to over.....stall...then died trying to start, so the battery is weak and needs charging or replacing. But that doesn't explain no juice to the fuse box.
Headlights worked though. Do the running lights and reverse lights, run through the headlight switch first? Meaning does the battery's power go to the switch and THEN to the fuse box?

Also-
I think I may have mentioned already there is no emergency hazard switch. I'm starting to get the feeling that has something to do with the hack job wiring. Whoever did it must've had to work around flasher switch absence. Being that they are year specific and NLA has anyone had to deal with using another modified switch?

timmy2 · timmy2's Garage

Take a look at the wiring diagram.
Battery power goes directly to the switch from un-fused terminal at fuse 2 to terminal 30 of the light switch (34). The fact you apparently have dash lights when you pull the switch means that it is working.(getting power)
The grey/red and grey/black wires get power through the switch contacts when activated and go through a grey colored 8 pin through dash connector back to the fuse panel terminals/fuses 7 and 8. The connector may be loose or corroded, the fuse panel connection may be the same.
They should also be activated with the ignition off and operating the turn signal either up or down to turn on the "parking light" feature for Europe. (same wires running to blinker/dimmer...
item (32)

mickey356 · 01-18-2016, 12:56 PM

Thanks Timmy!!
I am going to sit and try to absorb the wiring diagram better tonight. I'm not very experienced with wiring AND my eyes suck, so I'll need a bigger screen than iPad

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timmy2 · timmy2's Garage

Quote:

Originally Posted by mickey356

Thanks Timmy!!
I am going to sit and try to absorb the wiring diagram better tonight. I'm not very experienced with wiring AND my eyes suck, so I'll need a bigger screen than iPad

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Print it and grab a magnifying glass.

mickey356 · 01-18-2016, 05:49 PM

And readers too!!!
Ok, this looks relatively 'followable'. Now I have to wait for a little warmer weather and get the battery charged/replaced.

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mickey356 · 01-21-2016, 10:18 AM

Ok, got the battery charged and here is what I have - the fuse box pic with the "Y"s and "N"s refer to "Y" has power and "N" does not.
So it looks like power is coming through the headlight switch to the fuse box but not getting to the lights. I DO get power to the front passenger side running light.
Also, while fiddling around the relay circled came loose. It looks like some one rigged a relay to replace the original? There seems to be a plug for a relay that the one pictured was modified to replace.There are two connections running from the circled relay to the plug, a spade, which fits snug, and a clip to a spade that the wire came out of. I replaced the clip and put it back on but now the turn signals don't work anymore, that's why I'm assuming it's a rigged turn signal relay but I could be wrong.
Should all the fuses have power coming and going (aside from the aux heater)?
Thanks

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