So, freakin' German cars. Really, I have little to say for "German Engineering". So, I am rewiring the car from scratch (more or less - using old harness as a guide) and upgrading to the "correct" way to fuse a circuit with a Painless Fuse block. Anyway, it is easy to just run new wires to the item being switched on and fuse the hot wire to the switch = say headlights for instance... I fuse the hot in, then "splice" the wires that were at the original fuse panel (not splicing, running all new wire, but that helps paint the picture hopefully).

Then I get to the hazard light switch. There is about 15 wires off of that one switch! I can figure out the stuff for the most part - EXCEPT FOR HOW THEY ARE RELAYING THE FLASHER. I can't tell if they are intermittently breaking power (12V switched) or intermittently breaking the ground. And the design seems to have this crazy kind of 12V looping going on (tho' won't go into that). Anyway, I need to easily pull that relay outta the system (as the new fuse panel has the 12V signal intermittent relayed) but am worried about how the grounding works.

So, that paints the picture (hopefully), here is a straight-forward series of questions:

1. There is a black with green stripe and white swirl wire that is split - one goes from the switch to the steering column and the other from the switch to that freakin' relay. Does this carry 12V constant?? (I am assuming it is constant 12V to make the turn signals work by passing 12V from that wire to either the blk/wht or blk/green return to flash the lights.)

a. If the wire inquestion is in fact 12V hot thru the switch, then I can figure the rest out from there. If not, if it somehow gets an intermittent 12V supplied from that funky relay, please let me know and I can work with that too.


If it doesn't match anything above, then I will probably just take a hammer to the switch altogether, swear in the few German words I know, and just wire in my own switch. But I really want to keep the stock looking switch on the dash.

Worst case I pull out the DMM tonight and swear under my breath while I figure that switch out, but any help is very appreciated. I have spent HOURS yesterday and was up 'til 3AM (no shit!!) reading thru the wire diagrams trying to figure out that relay and overall loop. And I can wire a car no problem... so this is just un-freakin-buleavabul.

Further explanation of my confusion:

I think that 12V gets supplied thru the switch to the blk/grn/wht swirl wire to provide a path for 12V to excite the lights with the turn signal handle on the column and also power the relay. BUT, this is where I get all messed up - what really screws me up in that it MIGHT be that the relay supplies an intermittent power through that terminal - in other words, the switch doesn't supply voltage to the wire (and hence the relay), the relay supplies voltage to the switch! I am really typing all this out to think it through a little more haha.

The wires that go through the steering column never seem to intersect that relay again, only with that one wire. So in order for the turn signal handle to work, it is implied that the 12V comes intermittently from the RELAY, not 12V constant from the SWITCH. If so, then I need to provide power to that wire with my fuse block.

Take a look at this thread. I spend a long time figuring this out a couple of months ago-

http://www.914world.com/bbs2/index.php?show...c=47236&hl=


Basically, the flasher relay connects to +12v, and then ANYTHING that needs to blink is connected to the flasher's output, and turned on by grounding that specific item.

Turn signals get weird, though, because the circuit is designed to cause BOTH indicators to blink if an exterior bulb burns out. That's what is explained in the thread......

Understand how the flasher works, and you'll figure out the rest. I did, and I'm not that bright. (for proof of that- I put an hydraulic cam in my 914! )

GOOD LUCK!!

Jim

So I looked at your post (thanks btw) and saw your diagram below.

Click to view attachment

So, to verify, you have a 12V supplied wire (red wire, hot all the time), a ground wire (the brown one of course), then...

1. the black/grn/wht swirl has an intermittent 12V supplied by the relay? This makes sense to me... but do you agree it is intermittent 12V supplied back to the switch?

2. the blue/wht wire also has an intermittent 12V supplied by the relay?? This makes absolutely no sense to me and is the "circular thing" I mentioned earlier. Circular in that the indicator light has only two wires connected to it - either a blk/wht or blk/grn depending on L or R. THOSE WIRES WILL ALSO HAVE an intermittent 12V SUPPLIED TO THEM, right??? So that means the indicator light doesn't seem to have a ground, just 12v hitting it from both sides. The only ground I can figure out in that setup is at the flashing bulb. But current flow is the wrong direction and I can't see how that can work - I mean, it does apparently work but must be in a manner I don't understand.

This is very typical German engineering - just do the craziest, over-thought thing you can and produce it v. a very simple setup. It is like they went to meetings and if the guy presenting couldn't explain the circuit clearly, but it worked, then they picked that one

for sure this is the hardest part of the system! Everything else I already have a plan for (tho' hard to say if it will all work )

sunofahbeeeeeiiiiitch. Only thing worse that a German engineer is a half-Swedish one (me)

I have those factory manuals for the car but they are reprints I think - the wiring diagrams have NO indication of wire colors. I think originals may be actual color diagrams, but I have no idea as mine is all "grayscale". Long story short, when I follow the diagram I ASSUMED the wire to the left turn signal bulb was white/blk (to match the left side), NOT the right turn signal bulb. THose little diagrams are hard to follow but I bet when I get home later I will see the wire from the L post goes to the right bulb on the tach diagram.

That diagram another person put in your post, and your comment above about grounding through the other side, makes it all come together.

So you see why I was saying "there is no ground, 12V is supplied to both sides"?? I thought the left bulb got 12V from the blue wire AND from the blk/wht wire, which would essentially cancel out to me. Now that I see the right bulb gets hit with 12V from both sides so the right bulb gets cancelled out (doesn't flash) and the left bulb gets 12V from one side only (blu/wht) and grounded by passing through the whole freaking right light assembly.

What an epiphany. Cleverly over-thought - it is elegant in how it "indicates" errors as well, but goddamn is that difficult to follow. And just plain way to much thought for a car.

Still, IT'S A FREAKING MESS!!! But I think I have a plan. I am going to take my intermittent 12V signal from my new fuse block and slice straight to the blk/grn/wht wire that used to go to the relay. That should bypass that relay altogether.

All that other stuff with being able to turn the lights on over night on one side and so forth I don't care about, so I will simplify that switch quite a bit. And keep the wht/blk on the left indicator bulb but go straight to ground. That way everything is in a simple path - fused squarewave hot to switch thru a light of some sort to ground. Easy skeezy.

BUT THANKS A TON JIM, I can't say that loud enough as I would still be boggled without seeing your thread diagrams and your answers. I couldn't understand your thread until realizing that the wires were "backwards" at the indicators.

uhm, dude, how about haynes manual?

it gots all the diagrams you'll ever need. they're in black/white but have the colors printed on the wires.

or, spend $20 and get *color* copies of the same diagram if that makes things easier for you ...


and yes, all german cars of that area "switch the ground" and *not* the power ...

there's nothing wrong with the way the electrical was engineered, all it takes is some getting used to if you're an american iron kinda guy ...
Andy

Right on Andy - funny as I have a Haynes manual (what I bought originally with my first 914) and then "stepped up" to the factory set Anyway, I took yesterday off to start wiring the car, so I grabbed the Haynes to use since I didn't want to dirty up my nice one from the set - AND SAW THE COLORS all marked on the identical diagram. So needless to say, no need for the factory manuals!

It is just funny I happened to login today and see your post

As for fusing the powered item v. fusing the hot, the downside is this (and tho' really the only downside - it is a HUGE downside): If a short exists between the switch and the battery - it goes straight to ground and never pops the fuse. So you burn the wire. Which then burns through the wire next to it - which may also be to another switch with 12v unfused, so you basically end up with a bunch of wires on fire. With the GM-style setup, you have one wire with a fuseable link powering the fuse box. Then all wires off of it are fused, so if something grounds out anywhere in it's circuit path, it pops the fuse and cuts the power. And the fused lead by the link means you shouldn't have a harness meltdown ever.

The old harness in the 72 has "brown spots" from heat on a bunch of the wires all touching each other near the light switch... scary to think about as that would potentially burn the whole car to the ground and why I went to this painstaking process of converting over to the GM box.

FWIW. Either circuit will work (obviously).