Assistance with Restoring 73 Wiring Harness |
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
Assistance with Restoring 73 Wiring Harness |
doug_b_928 |
Jan 31 2018, 03:55 PM
Post
#1
|
Senior Member Group: Members Posts: 692 Joined: 17-January 13 From: Winnipeg Member No.: 15,382 Region Association: Canada |
My main Winter project is to 'restore' the wiring harness on my 73. I admit that of all the jobs involved in restoring this car, this is the one that creates the most anxiety in me. I took it out of it's container last winter, spread it out on the floor, and promptly proceeded to put it back in the container. But, the time has come to conquer this thing. I have 4 rolls of wire tape that cost more to ship to me than the tape itself, and I think everything I need to do the job. I have pieces of a 74 harness (which I'm aware is not the same) and have already used one of the correct connectors from it for one of the license plate light connectors. Overall, I think the harness could be a lot worse, but there are some areas where POs have made some modifications/fixes and I'm not sure what they've done and why. I'll be asking for assistance from the wiring gurus in the thread as I work my way through. I have the wiring diagram from Jeff Bowlsby's website, a multimeter, PowerProbe3, and cleaning supplies. I'm removing all the tape, inspecting, cleaning, and then installing new tape. I'm just going to clean and inspect the rubber covered sheaths as they seem to be tight around the wires and it seems unlikely that there is anything wrong underneath them (on the upside, everything that ever worked on the car during my ownership, which wasn't everything that was supposed to, still did right before I removed the harness).
Okay, so with that introduction, my first questions. Starting at the back, I've worked my way through the license plate wires, to the trunk light wires, and I'm currently looking at the fuel pump wires. My car had vapor lock, so the fuel pump was relocated to the front of the car. The mechanic just cut the wires, left the ground wire dangling, and spliced in a positive wire which he ran through the firewall (poking a hole; no grommet), under the carpet and through a hole in the front firewall, where he then spliced in the connector and grounded to a screw he added to the front firewall. Here's a pic of the wires: Because of the vapor lock issue, I'm thinking I should put my new pump in the front where the old one was (by the steering rack). I'm thinking of getting the NAPA Bosch fuel pump (N69133). From what I can tell looking at the wiring diagram, and I could be reading it wrong, the power wire goes to the 'regulator/relay plate). If it's source was at the fuse box under the dash I'd splice into the wire up there and put the original connector back on the wires in the engine bay (in case I ever wanted to put an original style in its original spot. If I'm correct about the wiring diagram, then, with my limited knowledge, I guess I have to run the power wire on the outside of the sheath (but at least it will be inside the new 914 rubber snorkel) and up to the fuel pump in the front? Is there any point in running the ground wire that way too, or would you just ground it to a screw on the car as it was before? Also, in the pic above there is a green wire that looks like it had a connector on it at one time. Does anyone know what that was for? When I look at the 73 diagram it only shows the black with red dots and the ground for the fuel pump. On the diagram it shows the, IIRC, 'fan blower motor' having a green wire. However, if that's referring to the blower motor for the heater, I think the wires and connector below were for that (note no green wire). So, to summarize, what's the best approach for the fuel pump wiring, and what is that green wire for? |
doug_b_928 |
Feb 24 2018, 02:35 PM
Post
#2
|
Senior Member Group: Members Posts: 692 Joined: 17-January 13 From: Winnipeg Member No.: 15,382 Region Association: Canada |
Technical question: the small black with blue wire that gives power to the gauge cluster lights was spanning from the gauges to the fresh air controls from outside the taped harness. It is originally that way, at least for this harness. It would be so much neater to make it a little longer (about 18” at most) and have it follow the loom for the fresh air instead of being a wire on its own getting tangled spanning two branches of the main harness. I measured he resistance in its original configuration as 14 ohms. Then I cut it and spliced in a piece and then rechecked the resistance, finding it to be 24 ohms. I realize that the longer the wire the greater the resistance. But that got me wondering if the factory had it that way to avoid problems with it being a bit longer. Will that change in length of a small wire create any problems?
|
Lo-Fi Version | Time is now: 2nd May 2024 - 06:57 PM |
All rights reserved 914World.com © since 2002 |
914World.com is the fastest growing online 914 community! We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ... |