Help identifying unknown wiring on 1988 911

[Phony930]

Anyone want to play “guess that wire”?

Trying to sort out a 1988 911 that has been modified over the years, and I’m still learning, one day at a time.

Took a couple videos if anyone wants to give a shot at identifying a few wiring things under the hood.

https://drive.google.com/file/d/1yZC4pppUTfAndgpSs6C5GgRs30YZzQIi/view?usp=drivesdk

https://drive.google.com/file/d/1TqAVSB3_MR3KNZ3SH6EvS9U9Z4FtA-Vv/view?usp=drivesdk

Thanks!
Bryan

[john walker's workshop]

Pics are better. Unknown links, ya know.

[Phony930]

[Phony930]

Or this one unplugged under the dash on the passenger side

[A930Rocket]

Keyless entry or alarm system in the first pictures?

I’m going to go out on a limb, and say it plugs into that round connection behind it in the third picture.

[Phony930]

Well I appreciate you taking the time to respond… I’m specifically looking to find what each of these are. Hoping someone has way too much 930 info in their brain and they will know, or they will know how to find out.

I could have put the round peg in the round hole, yes, but I’d like to know what is is and understand why it’s unplugged before start getting wild over here and potentially undoing things that are supposed to be done.

Baby steps… one calculated change at a time.

[mikesarge]

Does your fresh air blower work? If not, plug in that round plug into the hole behind it and give it a try. I’m almost certain that’s what that’s about.

The second one is not factory, so the only way to tell what’s going on is to follow it back.

[gerakroo]

First picture looks like the 4 pole connector from the tunnel harness to the DME (I assume 2 x black, 1 x black-violet and 1x yellow ?)

[Phony930]

Ok awesome, these make sense -- first off my blower does not currently work and I need to start looking into that so hopefully it's just this plug. The car does have the AC compressor and condenser removed. The AC lines are still in the front of the engine compartment with the ends taped off.

Also, the car was swapped with a 3.3t setup and changed to the CIS fuel system, so I know that certain wiring and other components have been modified, I just haven't identified some of it yet.

The car did have an old Viper keyless alarm installed which I just removed. The aftermarket orange wire with the spade connector on it was not connected to anything though. This aftermarket orange wire is connected to a red/white factory wire that runs alongside a bunch of brown wires. I'd love to identify what this red/white wire is -- any suggestions on how to trace that?

[wazzz]

Originally Posted by Phony930

Ok awesome, these make sense -- first off my blower does not currently work and I need to start looking into that so hopefully it's just this plug. The car does have the AC compressor and condenser removed. The AC lines are still in the front of the engine compartment with the ends taped off.

Also, the car was swapped with a 3.3t setup and changed to the CIS fuel system, so I know that certain wiring and other components have been modified, I just haven't identified some of it yet.

The car did have an old Viper keyless alarm installed which I just removed. The aftermarket orange wire with the spade connector on it was not connected to anything though. This aftermarket orange wire is connected to a red/white factory wire that runs alongside a bunch of brown wires. I'd love to identify what this red/white wire is -- any suggestions on how to trace that?

There are a few white/red or red/white wires but the most relevant for you would be the following candidates:

- From pin HN of Alarm Control Unit to factory alarm horn (via pins 5 and 6 of connector T10)
- From pin HN of Alarm Control Unit to Alarm Relay pin 6
- From Alarm Relay pin 2 to fuse # 2 of Fuse Block 1.
All there references are per the factory diagram for MY 88.

Here is a link to my own copy of the sheet where you'll find these connections. Download the file if you want to be able to fully zoom it in.
https://i.postimg.cc/PfKjK0vB/1988-Carrera-32-diagrams-4.jpg

[Phony930]

Interesting, I’ll be honest that I didn’t know the car had a factory alarm. Being that I just removed an old Viper alarm, think it’s worth the trouble to reestablish the factory alarm? I am not fluent in wiring diagrams but can probably ask a friend for help. I’d really love to learn how to understand wiring diagrams either way…

Here are a couple more photos of TWO different red/white wires…

1) one is smaller and goes through a grommet along with a bunch of brown wires.




2) the other is thicker and comes from behind the fuse box and has a factory connector on it.



Does that help clarify at all?

Also, do these relays look correct for either a 911 or a 930? My car started life as a Carrera and was swapped to a 930 engine — just working on understanding what’s what and identifying anything that leaves room for improvement.
(I did discover that there’s an aftermarket relay bringing power to the original fuel pump fuse #6 when key is turned to the on position. Without this the front fuel pump does not run but the rear pump does. I am not yet sure how the rear fuel pump which was added with the swap is powered.)

[wazzz]

Forget this line in my previous post above as I confused with red/black:

- From Alarm Relay pin 2 to fuse # 2 of Fuse Block 1.

Other lines are still correct.

The big short wire with a factory connector you're holding in your hand may be for the convertible top unit if it is connected to fuse #3 (the blue one starting from left on your pic). So no wonder it is unconnected if you have a Coupé or Targa.

Here are other red/white or white/red wires I was able to identify on factory diagrams for Carrera 88:
- A bunch of wires in the windshield wiper and intensive washer circuit around B13, B14, B15 of factory diagram.
- Another bunch at the Heater Blower Control Unit in B26 (but these are in the engine compartment)
- One big between ignition switch and light switch.
- A bunch at speedometer (N52 in diagram), which provide speed info to heater blower control unit and convertible top control unit.

And I think that's about it.
PM me an email address if you want all other sheets of factory diagrams. I have them as separate jpeg high res files and as a collated pdf.

[Phony930]

I am now trying to identify some wiring behind the gauges in the dash.
I believe some has been modified.

I have an unused red with white stripe wire, with a plastic spade connector coupler on it.

I have an unused brown with white stripe wire with a small (narrow) space connector on it.

I also have a black connector that is unused — I believe it originally plugged into my original tachometer, but the tachometer was changed to an earlier model year and individual spade connectors were tapped in to be used instead. Does that sound right?

I would also like to confirm the correct wiring on the back of a 930 turbo tach — I am replacing my non turbo tach with a turbo tach and need to get the wiring correct, plus add a boost gauge wire so that addition gauge works as well.

[Showdown]

What you need is an electrical flow chart. Then you can learn to trace your wiring, figure out which wire does what and answer your own questions. Google can help;

https://www.scribd.com/document/545334952/84-89-Porsche-911-Wiring-Diagrams-1985-Models-Get-Free-Pdf

http://911c1.de/porsche/Schaltplaene/plaene1-10_carrera_32.pdf

https://solopdf.com/porsche_911.htm


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[boyt911sc]

Originally Posted by Showdown

What you need is an electrical flow chart. Then you can learn to trace your wiring, figure out which wire does what and answer your own questions. Google can help;

https://www.scribd.com/document/545334952/84-89-Porsche-911-Wiring-Diagrams-1985-Models-Get-Free-Pdf

http://911c1.de/porsche/Schaltplaene/plaene1-10_carrera_32.pdf

https://solopdf.com/porsche_911.htm


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Brian,

Get hold of a factory wiring diagram and practice tracing circuit by circuit. It takes patience and a lot of perseverance to be successful in this type of project. It is mandatory that you have a good and reliable copy of the electrical diagram of your car.

Have a note book and do a lot of sketches until you become proficient and familiar with your wiring. Test and verify. Good luck.

Tony