Recognize this wire? 73S

[Haasman]

Trying to figure out what this wire goes to. I poured over the wiring diagrams but I am not sure where it goes or is used for ... It is brown with a white stripe.



I've been working all day on the dash wiring to determine why the directional indicators in the tach are dim. I've changed the bulbs, found, cleaned and verified grounds underneath and in the cowl area.

[edmayo]

Seems to me there is always an extra wire in the column, just make sure you have the correct wire for the horn by grounding it to operate the horn. Just tuck the other one out of the way.

[Haasman]

Thanks Ed. I did and the horn does work off the wire from the right side of the column (not pictured)

Still working on the dim turn signal indicators. I noticed the emergency brake light is normally bright. Hmmmm

[edmayo]

What voltage do you have at the wire to the bulb holder?

[Haasman]

Hard to measure because it is switching off and on.

[304065]

We need some better photos from a wider angle. Fortunately all the wire colors are original.

Brown is always the ground, this is the iron law of DIN. When the Germans modify the ground to DO something, vs. just grounding something, they add a tracer. So the brown/white you see dangling there, that is the wire that goes to the spring-loaded contact for the horn. The brown ground wire out of sight on the right, that one goes to the horn ring, and the other end is a spade that connects to one of the four bolts that hold the clamshell to the column (and thereby to ground).

Now, the dim signal indicators are a different issue. Did you clean the blinker relay contacts? Is there oxidation in the female sockets in the relay holder?

What would be ideal would be a wide-angle shot of the wires that enter the bulb holders on the back of your tach-- this way we can see if the orientation is correct. The wiring of the turn signals, and how they work, is the "Stonehenge" of the early 911 electrical system-- a hard to follow system logic that relies on balanced voltage on either side of the bulbs, wires from the right side hooked to the left bulb, coupled with the most obscure nomenclature from Porsche (seriously, Warren used to say that the most junior engineers designed the wiring diagrams after the senior ones did the system. . . and I think he was right).

I'm sure the solution is simple.

[Haasman]

304065- I appreciate your interest in these two items and especially your attitude in approach. Here are some better pictures

The infamous brown/white striped wire







Back of the tach turn signal indicator wires

[NorthernThrux]

Brown is always the ground, this is the iron law of DIN. When the Germans modify the ground to DO something, vs. just grounding something, they add a tracer.

Worth repeating. This (DIN standard 72551) holds true to this day. Just had the door panel off on my 2014 Cayman S to install some puddle lights and the true grounds are brown and switched grounds are brown/white.

Ravi

[Haasman]

Ravi- Just learned something:

the true grounds are brown and switched grounds are brown/white

thank you! Very helpful

[304065]

Good photos! All electrical threads should be documented so well.

I think the brown ground wire with a ring on one end and a faston on the other is the one that connects to the horn ring. Then the brown/white goes on the contact. You can see the rings on the end of the grounds that connect to the screws that hold the clamshell.

Also, shouldn't there be grounding tabs on the back of your gauges and a brown ground wire that daisy-chains across the back? The instrument lights get their power from the black/blue wire; as you can see, the other terminal of the bulb gets its ground from the brass case of the bulb holder against the metal socket. It looks like you have cleaned the oxidation off the bulb holder, good (they are usually dark brown from years of oxide). But remember, the instrument case is isolated from the body with a rubber gasket, so it's not going to get a very good ground connection that way. There is the ground pin for the tach, but I don't know whether that connects to the case of the gauge itself, or just to the board inside, I don't remember a case connection last time I had one apart.

Ravi, for fun Google up DIN 72552 it is the DIN spec for all the wire terminal numbers like 49, 49a, etc.