1968 Hazard Switch Wiring Issue (Car does not match factory diagram)

[R_Builder]

Hi Guys,

Did a little searching but no direct hits. Has anyone run across this? Chassis is a 1968 912 Karmann Coupe. My factory wiring to the back of the hazard light switch is white/red, brown, and black/white. Close to factory, but not quite the same as the diagram. I am bringing all the dash electrics back to life and everything worked great... then the last item I went after was the hazards. I looked at my (very old) notes and hooked wires up as it was when I got the car and no luck. Mind you I can't say whether or not they ever worked as I don't recall testing them way back when I got the car! Anyway, went to the diagram and noticed a difference so that seemed like a good place to start...

I am not really at the troubleshooting stage yet, more curious if this has been encountered before and corrected? I am good with wiring and know better than to trust old relays, but all the blinkers are working. only weirdness I see so far is that both bulbs for the turn indicators light up together whether I signal left or right so there are probably some lurking issues.

Thanks!

[304065]

I wouldn't worry too much about it, you should be able to measure electrical continuity between the black/white at the back of the switch and the black/white where it plugs into the L pin of the relay can down under the driver footboard. Even though the wiring diagram calls for a color change my guess is the contractor that made the harnesses just used the same color all the way, which doesn't matter electrically.

Reviewing: at the switch itself the red/white wire completes the circuit to ground, grounding pin S of the flasher and causing the L and R pins to energize simultaneously, powering the bulbs. The blue/yellow (in your case black/white) is a multiple off the L pin of the flasher to illuminate the bulb in the switch handle-- it's pulsing +12v and the other side is the brown ground.

For more than you ever wanted to know about the flasher circuit here's some work I did 10 years ago. . . I wrote it down so I wouldn't have to remember it!

http://forums.pelicanparts.com/porsc...rly-901-a.html

And the electrical masterpiece:

http://www.early911sregistry.org/for...elays-Analyzed

Always disconnect the battery before doing electrical work and observe common sense safeguards to avoid personal injury or property damage. Have fun!

[R_Builder]

Thanks John, I thought you might chime in. I will verify where that black/white wire terminates then go ahead and install the switch. I did already verify that the switch is working properly, so that should put me in a good position to start troubleshooting the hazard circuit. Thanks for those links... the search function lead me to them and I bookmarked them right away just in case!

Take care,
Doug

[MrJTP2001]

Yes, Karmann did change the color of the wire that runs from the Emergency Switch to L of the Emergency Flasher Control Unit on 68 Coupes. There are two wires connected to L on the unit, both are now Black/white.

[R_Builder]

Thanks guys. Good call on the wire coloring substitution... that is all it was. A black/white wire was swapped in for the factory diagram's blue/yellow. Same function and routing. Put it all together and the reason nothing was happening on the first try was some corrosion in the in-line fuse that is factory installed in the green/white wire that is part of that circuit. Cleaned fuse and holder and the hazards did come to life, but only the right side and no light in the dash switch. So that makes me think the L terminal on the "flasher can" down in the driver footwell is dead. Time to look at that thread you linked me to above .

Thanks again for the help,

[304065]

Easy enough to pull the carpet, remove the footboard with a 10mm socket and measure for voltage on the L terminal. It would be strange that the can would blink and yet not have power to L. . . suggests it's a connection somewhere. Good luck!

[MrJTP2001]

There are other instances of wire color differences between my 68 Karmann and the 68 shop manual. The latest I found was in the circuitry for the front trunk lights. The Black/white wire color in the manual is actually white/black in my car.

[R_Builder]

Easy enough to pull the carpet, remove the footboard with a 10mm socket and measure for voltage on the L terminal. It would be strange that the can would blink and yet not have power to L. . . suggests it's a connection somewhere. Good luck!

Indeed. Working my way to it, just wanted to make sure I could safely continue with assembly. I did spend time checking things when I was able to get the RHS working. That is when I found that there seems to be a loose part inside the can, so I will start there!

[Nordschleife]

Resurrecting this 1968 SWB hazard switch discussion to ask a specific question: how can I get the switch knob to illuminate when pulled? What am I doing wrong?

I have wired my switch to try to exactly match the 911/911L schematic (see diagram and photos below):

Terminal 1: White w/ red stripe wire
Terminal 2: Brown wire
Terminal 3: None
Terminal 31: This is the spade on the rear of the center bulb. Double spade with co-connected 1.) Black w/ white stripe wire + 2.) Brown loop wire connector between terminals 3 and K (shown as "31" in wiring diagram).
Terminal K: the other end of the short Brown wire loop connector

The hazard flashers work fine with the switch in this configuration, but the lamp/bulb in the center of the knob is not illuminated. I tested the bulb and its holder separately with a 12v power source - it works fine.

Note from earlier in this thread: 1968 Karmann-built 911s and 912s used the Black wire w/white stripe instead of the Blue w/ yellow stripe. One of those puzzling oddball "1968-only" items!

Best,
Andy