Mystery Wire

[ANIZZZZ]

Hello All,

New 1983 944 owner here and I've got my first of many questions!

I'm curious as to what this wire could be for? I can trace it under the air intake hose and to the back of the engine, near the reference sensors, before heading towards the fuse box. The car is missing the relay in slot 4 & 5, so I'm hoping it's related to the "headlight washer" and not something really important.





Some additional information about the car: It was purchased at auction with no maintenance history. After getting a battery in, it doesn't start and doesn't have a tach bounce. I discovered one of the reference sensor connections is broken and loose (the bottom at the connection point and front at the bolting location), so I just ordered a couple of those and a new DME/fuel pump relay. I understand new belts are a must, but any additional advice on where to focus with a mystery car would be greatly appreciated. I start feeling overwhelmed, yet extremely excited at the same time, when trying to inspect the car.

[c5pilot]

Looks like wire that goes to air flow meter and under the throttle body. Should have plugs for each.



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[ANIZZZZ]

I believe the wire you’re referencing is there.

[c5pilot]

Hmm. Ok I can take a look later as I’m about to get stuffed on brisket !


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[Ernie944]

Originally Posted by c5pilot

Looks like wire that goes to air flow meter and under the throttle body. Should have plugs for each.



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+1 the air flow meter won't work without them.

[c5pilot]

Anizzzz , can you trace the wire back to see where it originated from ? Might make it easier to compare.


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[ANIZZZZ]

Originally Posted by c5pilot

Anizzzz , can you trace the wire back to see where it originated from ? Might make it easier to compare.


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So I can trace it to the back of the engine near the reference sensors. It goes into the black group of wires pictured and then into the firewall. My guess is it comes up through the bump thing in last picture.

[ANIZZZZ]

Originally Posted by c5pilot

Anizzzz , can you trace the wire back to see where it originated from ? Might make it easier to compare.


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I can trace the wire to the back of the engine where it continues into the black group of wires (picture 3). From there it goes into the firewall and my guess is it comes up through the bump thing in the last image.

[dme]

Seeing those relays looks like a PO rewired the headlights. Could that be one of the original wires that went to one of the headlights? I think the color is wrong, but another option.

[ANIZZZZ]

Originally Posted by dme

Seeing those relays looks like a PO rewired the headlights. Could that be one of the original wires that went to one of the headlights? I think the color is wrong, but another option.

This would make a lot of sense to me. The headlights are wired in bright red and very clean (not original looking). I posted some pictures tracing the wire, but it looks like it’s pending mod review.

When I got the car, the wire was laying near the headlight motor and fluid reservoir. I can trace it to the back of the engine and it goes into firewall near the reference sensors; potentially popping up near the driver side windshield (wiper motor?).

[dme]

I bring that up because I made a similar mod to one of my earlier 951's. You use two relays and it keeps all of the headlight current away from the switch and brightens the headlights in the process. When you do it though, you only need the leads from one headlight so the other lead is just disconnected.

[dme]

Use a volt meter and see if you get any reading with the lights on dims and/or brights. measure between each wire and ground.

[c5pilot]

Originally Posted by dme

Seeing those relays looks like a PO rewired the headlights. Could that be one of the original wires that went to one of the headlights? I think the color is wrong, but another option.

Oh good catch. I thought the relays and wires were separate from the tan wire harness he was holding.


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[ANIZZZZ]

Originally Posted by dme

Use a volt meter and see if you get any reading with the lights on dims and/or brights. measure between each wire and ground.

There is no reading on the wires with the lights on high or low. Does the headlight relay normally run under the intake manifold? The turn signals aren't working, but the relay is completely missing in slot "XI" at the relay fuse bank.

[OK-944]

To me it looked a bit like a wire from one of the temperature senders from the front of the engine...but the more I look at it - the length, the shape of the greasy part - looks it could reach down to the oil pressure sender. Mine had this shape and length when I extracted it prior to dropping my engine.

So maybe look up from under the passenger side - just under where the oil filter is attached - and find the oil cooler assembly (small boxy-looking thing with cooling fins). Attached to the lower outside of this is the pressure sender - a small cylinder with two bladed wire contacts (different sizes to prevent reversing polarity). The end of the wire itself, where it attaches to the sender, should feature a rubber boot (possibly missing if the wire breaks) to help keep those contacts free of dripping oil.

[dme]

Originally Posted by ANIZZZZ

There is no reading on the wires with the lights on high or low. Does the headlight relay normally run under the intake manifold? The turn signals aren't working, but the relay is completely missing in slot "XI" at the relay fuse bank.

No, it did not come with a headlight relay. That is a mod that some people do to brighten the headlights and take the heavy current away from the switch contacts. What are the color of the wires inside the sheath? Looking at schematics, I think for your year the wires would be yellow and white IF it is headlights.

[ANIZZZZ]

The wires are blue/black and blue/white.


If this cylinder part in this picture is the oil pressure sender, it does appear to be missing a wire connection. Although. the mystery wire and the wire that is connected to the sender have very different paths.

[dme]

I believe the schematic says the oil pressure switch wires are Blue/White and Blue/Black. I don't have an 83 so I can't verify.

[ANIZZZZ]

Ok, from this thread (Is this the oil pressure sender?) the wires for the oil pressure sensor looks similar to my mystery wire in question. Also, my oil pressure sensor only has one wire attached to it and I can only trace it entering the firewall behind the front right wheel. Is there a good guide for this car's electrical system and the location of wires somewhere online I could utilize?

[ANIZZZZ]

Well I found this which makes me believe the blue blue/white mystery wire likely could be for the oil pressure sender, but what is the black wire currently connected? Ground?

https://www.manualslib.com/manual/392533/Porsche-944-Volume-5-Electrical.html?page=29#manual