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Posted by: narino Mar 27 2019, 10:26 PM

With the warm weather I've spent the last few days fixing wire connections and removing extraneous wires by the PO. A couple wires have me stumped, hoping for some help from the hive mind.

#1 - I have a heavy gauge red wire that is coming off the alternator, that the previous owner spliced into and ran through the longs to the hot terminal by the fuse box.

• Is this red wire from the alternator stock? I couldn't find it on the wire diagram.

#2 - The PO ran heavy gauge red wires through the longs to the hot terminal by the fuse box.

• I do not think this is stock, from what I've read there were no wires in the longs. I've only found reference to the charcoal canister lines in the longs. Could someone confirm whether this is correct or not?
• If these lines are not stock, then what originally used to go through the hole behind the dash, where these lines currently run? Pic attached for reference.

#3 - I bought some pilot fog lights and went to install them and saw my horns are in the way.

• Are these horns stock?
• Before I start tearing more things apart, are there other mounting points to relocate these horns away from the grilles?

Once I get these hot wires figured out I'll feel safer trying to start her and get her back on the road.

Thanks in advance!

Posted by: Chi-town Mar 27 2019, 10:43 PM

Wires in the longs = not stock
Horns = not stock

Sounds like the PO was trying to get around a wiring harness issue.

Posted by: narino Mar 27 2019, 11:37 PM

Thanks for the reply Chi-town.

Any idea about the Alternator red wire? I have no idea where it's supposed to connect. Oddly, it looks like it's supposed to be there, the wire goes into the protective sheath and through the rubber grommet on the alternator. Here is another pic of #1 wire looking from underneath.

Where in Socal are you?

Thanks again!

Posted by: Chi-town Mar 28 2019, 12:01 AM

Usually the heavy wire goes to the starter positive post with the positive battery cable.

I'm in Anaheim

Posted by: barefoot Mar 28 2019, 04:56 AM

New alternator wiring harnesses are avaliable from at least 2 sources and would be a good idea for you to replace yours.
This picture shows connections at the alt. the triple plug is duplicated at the other end and plugs into the back relay board. My origional harness was toast, so expect yours had some issues also. well worth the small $

Posted by: narino Mar 28 2019, 09:47 AM

Barefoot - Ahhhh... This explains a lot. I thought it went to only one terminal.

Do you happen to have a photo of how the wire is routed to the starter? Lots of different sized holes in the engine tin, not sure which is the correct one.

Thank you!

Posted by: malcolm2 Mar 28 2019, 10:26 AM

https://colorwiringdiagrams.com/t/porsche

I always spread the word about Prospero's Garage. Awesome wiring diagrams for many different cars.... year and model specific.

Looks like they have had a slight price increase. Now $25.

Posted by: ValcoOscar Mar 28 2019, 10:34 AM

I'm in So Cal (90621). If you want drive down Sun AM we can possibly tackle your gremlins together.

I have lifts so we can easily get it up in the air.

PM me

Oscar

Posted by: narino Mar 28 2019, 11:48 AM

malcolm2 - Funny, I just ordered these a few days ago. Looking forward to getting them.

Oscar - Thanks man, I appreciate the invite. The car is in various states of disassembly. When I get her put together enough to be road worthy I'd be down for a road trip to meet another teener.

Posted by: 76-914 Mar 28 2019, 06:08 PM

That Romex is priceless.

Posted by: bbrock Mar 28 2019, 07:31 PM

The hole where the PO's wire runs through the dash is "custom." There should be no hole there. My hunch is the PO had (or thought they had), a problem with the two large (12gauge?) wires that run from the pos battery terminal through the main harness that are the main power feeds to the starter switch and fuse box, and bypassed them through the long. I'd check resistance end to end through those wires end to end and go from there.

I agree that you should chuck that alternator harness and get new. I can't remember for sure, but I believe the 3-wire portion is supposed to feed through the hole just aft of where it is coming through in your pic but covered by foil tape. The hole it is coming through now is for the heater J-tube. If you new alt harness doesn't come with grommets, you can get them from 914Rubber.

Good luck!

Posted by: narino Mar 28 2019, 09:10 PM

bbrock - Thank you! That hole by the dash was going to bug me to no end. Glad I now know it was added by PO. Also per your reply I've rerouted the alternator wiring out of the J-tube hole.

Power wire in the harness: Good thought on possible resistance issue. I think that is what Chi-Town was insinuating, but I didn't pick up on it till now. I'll test for that tomorrow.

Starter/Alt wire: Looking at the Flow Diagram I noticed the wire from battery to starter is labeled as 2.5mm. Yet the wire from starter to alternator is 6.0mm. Why wouldn't the wire back to the battery be sized 6.0mm?

So glad to finally be finally figuring out these issues.

Thanks everyone!

Posted by: narino Apr 3 2019, 12:56 PM

Update and more questions.

• Tested resistance to wires and all reads good. I'll continue to remove the extraneous wires.

A while back a few wires to my headlight switch burnt out, which is why i'm tracing these wires now. Now that I have most of the wires repaired. How do I test the headlight switch? I'd hate to hook it back up only to refry every wire I just replaced.

*edit* Also, thank you to @http://www.914world.com/bbs2/index.php?showuser=104 . An email to him straightened out my confusion on why the starter to alternator wire was labeled as a smaller gauge. I need to get my eyes checked, it read 25mm not 2.5mm. *facepalm*

Posted by: Dave_Darling Apr 3 2019, 02:14 PM

Here's a dissection of an early switch: http://members.rennlist.com/pbanders/headlight_switch_internals.htm

Later ones are pretty similar. I don't remember the differences off the top of my head, though.

--DD

Posted by: narino Apr 3 2019, 03:18 PM

Thank you @http://www.914world.com/bbs2/index.php?showuser=121 . I had seen that article on pelican, but it doesn't explain how to test the switch with a multimeter. I'm not sure across which pins to test, and if I'm supposed to check for a certain resistance. Sorry, I'm a novice to the electrical stuff.

Posted by: bbrock Apr 3 2019, 03:45 PM

Since it sounds like you'll be trying to use the original wires for your starter again, a couple things to consider to hopefully avoid whatever problem the PO was trying to fix with the bypass. Consider replacing the electrical starter switch so you know you are starting with a good one (buy the expensive Porsche one), and think about adding a starter relay so you aren't sending a billion amps through your main harness every time you start the car. @Mark_Henry has a good write-up on how to do it.http://www.914world.com/bbs2/index.php?showtopic=308904&mode=threaded. My gut tells me one of those two things might have been behind the reason for the fat red wires up the long.

Posted by: narino Apr 3 2019, 06:33 PM

Thanks @http://www.914world.com/bbs2/index.php?showuser=20845 . I'm going to rebuild the alternator/starter harness and the battery cables. I did them on my other car and still have the tools and some lugs left over.

I'll definitely look into the Porsche ignition switch and starter relay.

Thanks!

Posted by: JeffBowlsby Apr 3 2019, 09:16 PM

You can test the switches with this:


Attached File(s)
 DashSwitches.pdf ( 127.27k ) Number of downloads: 63

Posted by: Dave_Darling Apr 3 2019, 09:23 PM

The headlight switch is a switch--or rather, several switches in one housing. With one exception, the pins either contact other pins or don't, so the resistances you are looking for are "infinite" (no connection) or "zero" (dead short or close to it).

The one exception is the instrument light section, which has a rheostat--a variable resistor.

All the below is from the 74 wiring diagram; other years may have differences. The headlight switch has three positions; in all the way, out one stop, out all the way. I have labeled those positions 0, 1, and 2 below. (Though I could have those backwards.)

Pin 15: Should have no connection to any other pins in switch position 0 or 1. Should connect to 56 and 56K (only those) in switch position 2.
Pin 30: Connect to 30b in switch position 0. Connect to pin 57 in switch position 1. Connect to 58L, 58R, K in switch positions 1 and 2.
Pin 58a: No connectivity to any switch other than 58b. Variable resistance from 58a to 58b depending on knob rotation.

--DD

Posted by: narino Apr 3 2019, 11:24 PM

Jeff & Dave thank you so much!

Posted by: narino May 12 2019, 04:07 PM

Finally got all the supplies to build the cables. Question on which wires go where in the rear engine tin. See attached image.

#1 - From engine bay photos it looks like the black wire from battery (positive) to starter goes through hole in the rear tin nearest the battery. Is is supposed to lay on top of the transmission?

Are #2 and #3 routed correctly?



Thank you!

Posted by: 76-914 May 12 2019, 04:58 PM

IIRC, there is/are 1 or 2 small holes in that big rear tin that an OEM plastic clip attached to and thusly held the wire off trans. Don't want that cable rubbing anywhere!
EDIT: I went back and found these pics. I couldn't or didn't locate the OEM clip. You can do this with a wider zip tie. Pics show both sides. No it doesn't pull through if you use a wide (^mm?) zip tie.

Posted by: narino May 12 2019, 08:05 PM

76-914 - awesome possum, thank you!

Posted by: narino May 31 2019, 05:13 PM

A setback. After cleaning the fuse panel under the dash, I cracked one of the plastic legs off. Ughhhhhh!

I tried regluing with Tech-Bond, but it won't hold with the pressure of the wires. Anyone have a better bonding agent or method I could try?



I don't think I'll have her up and running for wcr.