So now my next electrical problem is my interior light on the back pad between the seats. The light and fixture are brand new and the wires seem to be fine.I tested the light out side of the car and it does work.I grounded it with a pig tail and it still wouldn't light so I checked it with a meter and it doesn't seem to have much power if any it think I got a reading of a couple of volts but still not sure about that. It will not light on any of the switch positions. Could it be the door switches? What other electrical items are on that circuit. Which fuse in the stock fuse block is it?
Thanks all!

Remove each door switch and clean the pointed connection and the 'v' shape receiver with an Xacto knife or a razor blade.
Slide the push-on connectors on and off their blades repeatedly to improve connection.
As I recall the switches are all on the ground side of the lamp.
The power wire is less than 12v ? .... (the green wire) check that at the fuse box connection.

One of the first things any 914 owner should do when they get their car is chase down and clean the dozen or so grounds. Makes a bunch of gremlins go away!

The door switches ground tje light.

Mine were just worn out.

I use a dremel tool with a wire wheel brush on a flexible wand attachment to get off all the corrosion & or paint

The power wire should have constant 12V. Check from it to a good ground, like the battery (-) terminal. If it's less than 12V, check the (+) side of the circuit for dirty or bad connections.

The ground side of the circuit is generally more likely to give trouble, so that should definitely be checked as well.

--DD

I believe Bowlsby has a map of 914 ground locations on his site...

Both of the wires going to the fixture is black with stripes. One of the wires has a larger female connector and one is smaller. I'm assuming the smaller is the ground.

There should be three wires. One black, one brown, one brown with a white stripe.

Sounds like someone has monkeyed with your wiring. You may want to pull the back pad out and see what has been done.

--DD

Right again Dave.
When I said 'green wire' I was confused with the wires for the rear defog.

Often times the door contact switches will be bad.
Especially the early ones that have 4 terminals.
Both were bad on my 71 and I went through about a half a dozen of supposed good switches before I found a set that work.

If the door switch is bad, there is no way that interior light is going to work correctly.
And it's true; you need a full 12V+ for that light to light up.

What is link to all the "ground" locations ?

So I removed the back pad and the only wires long enough to reach the light are all brown with white stripes. There is a connector with 3 wires attached and a connector with 1 wire then there is one with a smaller connector. All the other wires down there are the seat and seat belt stuff. I tried both of the connectors and still no power to the light. Both of the door switches seem ok with good connections and a strong spring also I did clean the "v" contact as best I could.
Am I missing something here?

When you say the switch has good connections, what do you mean?
With the button or spring out, dId you check each pair of pins for continuity with a multimeter?
That is the only way to really know.
With the button in or spring compressed, the multimeter should show lack of continuity across each pair of pins.
These switches really do fail after a number of years and bazillions of times opening and closing the doors.

here's Bowlsby's diagram

I'll test the switches and see what I come up with.

I have the same problem as well. But I have plenty of time to fix it. Most of my OEM wiring was dry rotted. Mine seems to be the door switch. The middle setting will keep the light on but will not go on with the door open.

My problem is power to the light, weather the switch is good or not I still should have 12 volts to one of the wires,all the switches do is ground it to make it light up that's why my switches probably are not my problem.

So how did you test it then? That would be helpful to know.

You should have 12V at the black red striped wire. Assuming the car is a 73. The power comes off the fused side of fuse 11. Test the wire at the end for 12v against a known good ground.

If you find 12v there then the power feed is good. If not then the wire is suspect if the fuse terminal checks at 12V.

Make sure the connections are clean.

Hope this helps.

Find the solid brown wire, and find the black (or black/red) wire. The latter has a constant +12V and is how the light gets powered.

--DD

The car is a 74,there are only brown wires one is a triple brown with connector one is a single brown with connector the other is the smaller single brown wire. I cannot get 12 volts out of any of them.
There are no black red or green wires and nothing looks monkeyed with.

Pelican has the current dlow diagrams on their site. It shows a red and black wire feeding the light from the power relays. There are then a grouped set of three grounds and a switched ground feom tje door switch.

Take the backpad off. Maybe it fell behind the pad.

Good luck.

See diagram from Pelican Parts.
W is your light switch and F2 and F3 are your door switches.
You definitely need a black wire with a red stripe for power to your light.
As mentioned above, it may have fallen down behind the backed.

Click to view attachment

Run a jumper back to the power source direct,wires get scewed in the tunnel,had several myself that needed attention,good luck.

I have that same diagram in my book. I've removed the back pad and my wires are all brown.obviously my power wires are long gone. My next question would be where can I sorce the power to get up to the fixture and will it still function properly as long as I have the proper grounds attached.

Is there a wire at the relay end?

Just run it like the diagram if it isn.t there.

Hi,

Picking up this thread with the same problem. My '74 2.0 is absent power at the Black/Red wire, this wire (according to the current-flow diagram within this thread) originates at the Seatbelt warning system. (See connector J34, terminal 30). I have already jumpered the starter wire (big Yellow) so I believe if I jump this one to hot as well I should be done with the seat belt relay? Are there any other surprises? Seems like the relay is a connection point for various other circuits (oil pressure and more) so removing it and heat-shrinking the cut wires would not seem like a good idea.
Looking for guidance as to finding an alternate hot for the interior light.

Seat Belt Relay Functions
----------------------------
1. Starter Power interlock (removed)
2. Weight on Seat(s) switch for Fasten Seat Belt light (removed)
3. Junction for Power for the interior light (no power)
4. junction for oil pressure (intact)
5. various other connection junctions. (not touched)
6. Relays - I have no relay on this board.

Teener,

Here is the source of the confusion, if you look at the diagram - Black/Red is sourced at the Seat-Relay-Connection. This may be incorrect since there are posts stating that the Black/Red is sourced at the fuse box under the dash.

I will ring out this wire and post my findings tonightor ASAP<

THANK YOU Teener!

I think you misunderstand the diagram. The black/red is not sourced at the Dreaded Seatbelt Interlock Relay, it is merely connected there.

There is a black wire crimped into the connector with the black/red one to the light. This runs over the track 56 on the diagram, where it is crimped into another connector with another black/red wire. Trace this back across the page break, and it connects to the "downstream" side of fuse #11.

All of those points are electrically "identical" to each other (modulo some resistance in the wires and any dirty crimp connections).

Fuse #11 gets its power directly from the battery, through red wire.

So first check fuse #11. Is it popped? Take it out of its holder and look; it isn't always obvious when our fuses are popped unless you remove them from their holders. Next, does fuse #11 have power on the "upstream" side?

--DD

OK,

Dave is correct(of course), though there is more information. I buzzed the two wires at the dash fuse: Number 11. Here is what I found. Two wires come off the fused terminal of Fuse 11. One is black and with red band every centimeter or so, the other is Black with a Red STRIPE. The one with the stripe terminates at the 1st relay on the left (as you are in the drivers seat) on the Fuse Box (frame) under the dash. The other one with the red bands enters the tunnel and then comes out of the wire bundle at the gear shift area. See the picture below.

Click to view attachment

This Black/Red-banded wire is then terminated in a connector which powers (the clock?) some of the center console items that need an always-hot wire. Within this connector the Black/Red is also connected to a Black Wire of a smaller gauge. This is the wire that is then routed through the back of the tunnel into the bundle that goes to the Seat Belt Monstrosity under the passengers seat. From the monstrosity, as Dave says, there is ANOTHER connection from this black wire back to the Black/Red (Red Bands). I, for sanity sake, highlighted this connection (orange circle) in the picture below.

Click to view attachment

If I remember, my '70 1.7 did not have any seatbelt lights. So I suspect that at one time the Black/Red Banded wire ran to the light from the fuse box. when the center console was added or when the seat-belt Nanny was added, the Porsche engineers must have decided to use a simple black wire to power HOT the Seat Belt Nanny. Using the Clock Connector may have been an optional addition (order the clock and get a black wire!?!). Perhaps doing this is how they kept from having many different wiring harnesses in the inventory....??? - I imagine this change-order could have been done on the factory floor???

Funny that the Black/red wire is long enough to be routed back through the tunnel to the connector, so rather than replacing Black/Red connection at the seat belt monstrosity (which I did) it could be connected to the Clock Connector. Not sure why they didn't keep it Black/red all the way from the Clock Connector to the Seat Belt Monstrosity????.....certainly if they did, we would not be having all of this fun!

One more item - half way through this project I discovered that my VOM had an intermittent open circuit within the Hot probe......Cut it in half and threw it away. Was going in circles for a while....grin.

I trust that everyone that reads this does not mind my brevity? <;^}>

CTC911CTC

Just hooked up my interior light before sending the car into storage. The wires were taped off behind the back pad, just had to figure out what went to what. The first and easiest thing to find (theoretically) is the ground wires. In my case there are 4 wires to deal with, 2 individual wires that went to ground (I forget the colors and it doesn't matter). One was constant ground and the other went through the door light switch. Come to think of it, I never did test the passenger side switch (hope it works, will check when I visit the car next week). One lead of the ohm meter to good grounding point and the other to each individual wire till the meter beeps continuity. With both doors closed two wires read to ground. Open door and one ground went away. Test again just to be sure. The one that went away is your door, the other your constant ground.

Okay that takes care of the grounding wires. The other two wires were connected together via a piggy-back terminal that could slide onto the switch. Also those two connected wires read 12v to known good ground and my existing ground wires at switch location. Then had to figure out what wire goes on what terminal of switch. Hook it up wrong and blow a fuse. There are probably more than a few pictures out there showing where what goes to what.

Dang, just looked up some pics on google and found out my light is actually from a 911 Porsche. That explains why I had to cut the back-pad hole larger to fit the light in. Was going to explain where to hook the wires up but since the terminals are not the same I'll stop the post here. The point was how to determine what wires are ground and what are 12v positive. Hope this helps.

There are some vw lights that look identical, but are not constructed properly and don't work.

Solid brown is always ground. The switched ground stuff (like the door-ajar switch wires) are very often brown with a white stripe.

--DD