I'm going through my wiring harness with a fine tooth comb and I have a couple of questions.

In this picture:

I. What are these four connectors for? I think they are for the center console. Is that right?
II. Is this green wire for the parking brake switch?
III. Are the brown wires for the door switches and the black for the internal light.
Click to view attachment

What is this for? I believe it mounts somewhere under one of the seats and is used to connect the harness wires to the door switches. Where does it mount? Which accessories are connected through it?
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The plastic connector holder on my turn signal switch is very brittle. I don't suppose there are any aftermarket replacements?
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Lastly, where can I purchase all new grommets for the wiring harness?

Thanks.

George

1) yes center console, I don't know the specifics of the console wiring yet.

2) green/white is for heater blower switch,
I think the brake light wire is the longer brown/white wire with the interior light wires and routes behind the driver seat.

3) 3 wires go to the light, black wire - power for the light, brown/white - to the door switch , brown wire - ground

The plastic piece is the seatbelt warning relay/module and it mounts under the pass seat.
But the harness in the picture does not all have the wires for the seatbelt warning relay/module. The harness looks like an early harness with the simple seatbelt warning light.

Did the harness come with the car?
I believe each model year has a different harness.
Trying to use a different year harness is not advised.

After market switches Are or were available, haven't looked recently.
The plastic pieces separately, not that I ever have seen.

I would start with 914rubber.com for grommets.

Good luck.

Jim

The e-brake switch wire is in group III. One of the brown wires with white stripe. Check continuity between that and the light in the gauge. Yes, turn signal switches are available, but as always the originals are better.

It looks like that harness might be from a 73….which is close to a 74, but without the seat belt interlock (only buzzer) and 10 pole headlight switch (instead of 11).

Thank you Jim.

I have the original wiring harness from the car but it is pretty beat up. I think this harness is from a 1972 but I am hoping to use parts from the original to fix this one.

I'd like to know if you think that is a really bad idea. I have a line on a used 1974 harness that I could use instead.

Thanks.

George

Thank you Ian.

I have all of the switches that came with the harness so the 10 vs. 11 pole might not be a problem.

I also have the seatbelts for the same year as the harness so that's a match.

George

Recommend you get the 74 harness for your 74 car.

Here are the comparative differences for your consideration:

https://bowlsby.net/914/WiringHarnesses/doc...nessIDGuide.pdf

Thank you Jeff.

I'm going to compare all of my components (gauges, switches, location of the fuel pump, etc) and determine if the harness matches. If not, I'll have a lot of problems to solve.

I purchased this project as a bare chassis and a whole bunch of parts. So I'm not sure what I've got to work with.

George

Harness in question has to be a 1973. 70-72 had no center console gauge connections. 1973 would be my choice to use. 74-76 had interlock crud. Most people by passed all of relays by plugging the two yellow wires together. Seat belt plugs may be the only questionable part of swap. Just find some 73's belt holders to use.

Thanks Mark.

I concur that my harness is a 1973. I just checked it against the ID guide and it is indeed a 1973. Since I have all off the correct components for the 1973 harness, it seems that it would be easiest/best to build it out like it was a 1973.

Are the relay boards identical between the 1972, 1973 and 1974? I have two identical relay boards, both of which test out perfect.

Thanks.

George

This build is going to be a frankenteener.

1972 engine case and bumpers
1973 doors and electric
1974 chassis

Yes the relay boards are the same.

Jeff is correct it is best to use the harness that matches your car since you won't be surprised when things don't fit or work.
It sounds like the 73 is workable.

I did not take the advise of others or myself and I spliced the back half of a 75 harness into my 72. I also added a some wires to the harness for later use.

Good Luck
Jim

Thank you Jim.

Is moving the fuel pump under the gas tank a common mod? Is that standard on the 75 and 76 914s.

George

Yes. It prevents the vapor lock that many 914's with fuel pumps in the engine compartment suffered with.

Thank you Mepstein.


George

It also routes pressurized fuel in the center tunnel through the cabin. Personally I feel safer with the stock FP 70-74 location. If vapor lock is an issue, the factory service bulletin describes a fix that works well.

Thanks Jeff.

That is an interesting side effect to note. I'll search for the factory service bulletin.

You're welcome...

Here is the link:

https://bowlsby.net/914/Classic/zSB_1973-10-06_P213.pdf

Cool. Thanks Jeff.

I think Porsche moved the fuel pumps on most of their cars to the front and I’ve read that it’s better for pumps to push fuel from the tank than suck it from a further distance. I’ve been in a bunch of 914’s that suffered from vapor lock. Some of my own and some with friends. Most recently in a ‘74 with a pump under the engine mount. It took a spray bottle filled with water and lots of breaks to get us home once the engine compartment was heat soaked. A couple near misses in traffic when we stalled out at the wrong time. He moved it to the front (stock 75/76 location) and never had a problem again.

Regardless, use stainless steel lines, fuel injection hose and the correct clamps for your fuel system.

I'm making great headway with my wiring. I'm working my way from the back to the front, inspecting, repairing and cleaning. I've also moved the fuel pump connections to the gas tank area. Unfortunately, I have couple more questions..

What is this harness for? It was in the box of electrical parts. I have no idea what year it is from.
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Here are some close ups of the connectors.
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Two round plug connectors????
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Of course Porsche/VW would have two different kinds of door switches. Can I assume that the one with two connections would be the correct version for a 1973?
Click to view attachment
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Lastly, I haven't yet found where the door switch wires branch off of the harness. Any advice on where to look would be appreciated.

As always, many thanks for the information

George

Looks like the single pole switch in your pics is for the e-brake. Pretty sure the door switches for 73 were 4 pole. 74 and up were two pole. You’ll find the wires on either side of the instrument cluster wiring. They should have small female spade connectors.

Took me a minute because the harness is missing plug but it a a heated back window harness.

Thank you Ian!

I'm having a bit of trouble reading the wiring diagram.
Click to view attachment
The wiring diagram has:
the door switches as brown/white (both wires to both switches?)
If both wires go to both switches, in parallel, won't both doors have to be open to break the circuit?
the parking brake as brown/yellow
the interior light as black/red

Do the door switches ground through the chassis?
Does the parking brake switch ground through the chassis?

Thanks.

George

Thank you Mark.

I'm fairly sure that my rear window doesn't have any wires hanging off of it. (It is wrapped up and in storage right now.)

I also don't have a switch to turn it on. I'm guessing that I don't need to install that harness.

Thanks.

George

@GeorgeKopf the wiring on my 73 harness doesn't follow that color scheme. Or the colors have faded. With regard to the door switches, I'm not sure exactly how the circuit works, but I know there are 4 connections on each switch. Looks like your diagram only has two, so it may not be for a 73. Recommend picking up a diagram from prosperos garage - http://www.colorwiringdiagrams.com. They seem easier to read. At least for me!

When a door is open the switch closes completing the circuit to ground

From '74 on they ground thru the switch body

Correct, thru the '73 model year the switch had 4 contacts and grounded thru a wire.

Yes on all years

@GeorgeKopf @iankarr

Thank you Ed.

It occurs to me that using just the two pole switches should work just fine. Grounding through the chassis or the brown wires should be identical.

Thanks.

George

I've traversed the entire harness and am now deep into the dash components. It looks like at some time the wire from the light switch to the parking light indicator completely melted. The sheathing is stuck to multiple wires and there are brown marks everywhere.

Any idea what could have caused that melt down? I'm wondering if the wire rubbed through the light holder and grounded to the gauge. If so, I'm thinking of replacing all of the little bulb holders with ones that have an attached male flat connector. (Instead of the kind where the wire goes through the end of the bulb holder.)


Editors note: I was reading the 1973 fuse box wiring diagram and found this gem.
"High Beam indicator (Tach) and parking light indicator (Speedo) are unfused…"

So that explains that.



Thanks.

George

That is the accessory harness to control the optional defrost R. glass. Its missing the relay board connector (hard to find)
It normally threads through the snorkle at the firewall, yours has been removed.

Thanks Rich.

Now I'm working through the gauges and I think I've got it figured out.

My combo gauge looks like this:
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Gauge wiring for 1973 Porsche 914.
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Here are some pictures of the tangled mess of wires. I left off the gauge illumination (blue/black) because it was cluttering the pictures.
Combo GaugeClick to view attachmentClick to view attachment
TachometerClick to view attachment
SpeedometerClick to view attachment

Please let me know if I've got this wrong!!! If so, I'll update the drawing for posterities sake.