Ignition Switch / Dash wiring questions

[kclem19]

Hello,

The car is a 1979 911 SC that I bought as a rolling chassis. I'm beginning to test the electrical in preparation to install the rebuilt engine. Currently, I have a few questions:

1) There were three of five 6 pin plugs that weren't plugged behind the ignition switch. One comes out of the ignition switch and it was easy to match since it only has 5 of 6 pins. Can anyone help with the other two? See pictures (these are looking up). Looks like one is from the hazard switch (I think this one should plug next to the headlight switch) and the other comes from the passenger side of the dash (but have not traced it back because it goes up behind the dash). I took a look at the wiring diagram for the 1978 911SC on pelican but i couldn't locate the these connectors on the drawing.

2) Also, pin #1 on the 14 pin engine connector is +12volts on "acc" or "on" ignitions positions instead of only during the "start position".. I also thought i could have had the wrong pin so i checked each of the 14 pins and none changed from 0v to 12v upon turning to the "Start" position.

3) When reading current flow diagrams, is there a legend for the symbols used or any other helpful hints to better understand these?

Thanks in advance,
Kelly

[SpyderMike]

Found this on another post.

"On my 75 911 the plugs go as follows. Starting on the top left w/top being towards windshield and left being towards drivers door #1 headlight switch #2 emergency flasher.

Next row below -#1 ? #2 wiper switch #3 ignition switch. I did not mark #1 on the lower row, when reconnecting put the one that is left over here."

Please post if that works for you.

[kclem19]

Thanks. Did it as above. More things worked as i plugged them in one at a time. However, there are still quite a few loose ends: power window switches getting hot but aren't working, lights aren't working (yet - gauge back lights come on and one of the parking lights sort of work, no blinkers), and seems the starting circuit isn't working correctly..

I was hoping to find more "formal" information on these or more details for what these 5 plugs are for since there is always potential to melt down things when guessing. Does anyone know where you'd find info on which plugs go where or is it simply a wire tracing game?

Also, any help with #2 or #3 is appreciated.

[SpyderMike]

That Ignition Switch one has most of the power going through it. It acts as the main power distribution switching. Power also goes from there to the Light Switch and from the light switch off to all the lights.

Here are a few posts form when I redid my electrical scheme:

understanding the ignition switch

Understanding the Emergency Flasher Switch

I can't help on 2 as I haven't worked wiring back there in the engine area. Although you might find a clue looking at my link regarding the Ignition Switch.

Post pictures of the symbols you question and you will get answers. I am unaware of a legend.

Mike

[timmy2]

http://www.e38.org/understanding%20euro%20wiring%20diagrams.pdf

[SpyderMike]

Hey Dennis,

Nice find! By any chance, do you know the proper identification/function of the 5 bulkhead connectors under the dash by each location? It has come up in three posts very recently. I haven't come across this information and I think it would be nice to know. I figure if anyone would know it would be you. If not, then I might just unfasten my loom there and figure it out.

Mike

[timmy2]

I believe it is headlights, hazards, turn signals, wipers and ignition from left to right. Going by memory as I'm off to bed now. I can confirm tomorrow night.
(Headlights and hazards may be reversed)

[kclem19]

Further troubleshooting on #2
-previously, I was testing without having a "coil" or solenoid wired to the #1 on the 14 pin at the engine bay. I used a spare relay as a dummy starter solenoid and the voltage dropped down to 6volts in the "on/run" position. but I still think it should go to zero
-I removed the ignition switch and pin 50 only had continuity during start position. Switch is good
-I checked continuity on the plug for the ignition switch (with switch removed). And found continuity to the 30 pin. I believe this is incorrect
-I began tracing backwards. Ignition switch plug to bulkhead was good. Remove some of the HVAC stuff in the luggage compartment to begin on the other side of the bulkhead. Found that there is one wire off of the main yellow line that is causing this problem. After removing it from the circuit, the #1 pin at the engine bay goes between 0v and 12v from run to start.

Now, my problem is I can't figure out where this problem wire goes. It looks like it could be into the cruise control bundle but I'm not sure. The wire is pictured below - it is the smallest of the yellow wires. Any idea what this one is for and where it might go?

[kclem19]

Anyone know where this little yellow wire goes? Also, would anyone be willing to check the voltage at the starter solenoid with the ignition in the "run" position? I'm showing 6 volts but I would expect zero.

[bugstrider]

Originally Posted by kclem19

Anyone know where this little yellow wire goes? Also, would anyone be willing to check the voltage at the starter solenoid with the ignition in the "run" position? I'm showing 6 volts but I would expect zero.

I was digging around under the dash yesterday in our 78 SC. I just got home from work at 0400 my time and I can't see straight at the moment. I'll check a little later after some needed rack time. I think it might be the power supply for the radio. I removed our radio and aftermarket alarm due to age and I think it was related to that. I have the same little yellow wire too.

I'll take some pics on what I find
Cheers T


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[SpyderMike]

My schematic shows a small gauge yellow wire going off to the Heater Ventilation Switch which controls the Heater Ventilation Relay which powers the Heater Ventilator. Could that be it?