Help! '71 Restomod Wiring Woes. Test Your knowledge. I Failed!

[Uwon]

Background, Bare metal restoration of the Ugly Duck. Go to my thread "Sweet Transplant" if you want to get details. Warning. I'm really not very good at electrical stuff and electronics.
Problem #1- Windshield wiper wiring. As I dismantled the car, I took pics along the way. This pic shows what I think is a Capacitor (?) screwed into the underside of the dash accessible only from the frunk.. It was not plugged into anything and the PET does not show that this belongs to a '71 911. Is this correct? Do I need it?



Problem #2- Wiper motor wiring, I have three different wiring diagrams and they all refer to numbered positions on the wiper motor....but the wiper motor has no identification numbers for the contacts. Where do they go?





Problem #3- I would like to instal a Potentiometer intermittent wiper action and I have a dash unit that came out a '86. Any suggestions on how to wire it?

Many thanks in advance.
Cheers,
Johan

[timmy2]

I see numbers under the terminals stamped into the pressboard.
Wiring in a later intermittent control would be a real challenge. You would need the relay that works with it and figure out how to wire it up.

[Jonny042]

First one is probably a radio noise capacitor. Most likely not needed. Careful - that black wire is probably a +12vdc if factory but also could be a ground if it was added post works (brown is factory ground on these cars).

Timmy is right about the numbers on the wiper motor.



Does this add up with what you're seeing? (Edit - I think it does although the "5" in "53b" is obscured and perhaps the 53e and 53 are transposed). The brown wire (ground) goes to the terminal bolted to the case and the red/white wire (which is ignition switched 12V) goes to the other one.

[Jonny042]

As for the intermittent wiper control, if you have the dash potentiometer and the black box to go with it, it's a hilariously simple add-on to the system. As a sometimes electrical designer I get a real kick out of reverse engineering the way new features got scabbed into these cars without adding to the basic harness. I guess they had a lifetime supply of harnesses on the shelf and didn't want to create a new part number every time they added something on.

I'll have to dig into it further in terms of the actual connections but really all it does is create a pulse that's teed into the low speed wire intermittently depending on the dial position. And then depends on the auto-park circuit to complete the wipe. You'll probably know from driving the RST that the intermittent setting works with or without the wiper switch on.

There is a possibly more modern and cool solution here:

https://www.revolutionelectronics.com/Products/intermittent-wiper-module/

I could help with either of the two above solutions...

[Uwon]

Thank you so much Timmy and Jonny. Obviously I needed to clean my glasses and improve the close up lighting in the garage. Now I can see the numbers if I expand the original pic.
The capacitor is likely a leftover from the previous owner’s huge boom box stereo system. No need for it now.
Cheers,
Johan

[timmy2]

Noise suppression Capacitor connects to red/white power wire then the black goes to 53a. Or if you don’t have an original radio with no noise filters, just remove it and run red/white to 53a.

[Uwon]

Originally Posted by Jonny042

As for the intermittent wiper control, if you have the dash potentiometer and the black box to go with it, it's a hilariously simple add-on to the system. As a sometimes electrical designer I get a real kick out of reverse engineering the way new features got scabbed into these cars without adding to the basic harness. I guess they had a lifetime supply of harnesses on the shelf and didn't want to create a new part number every time they added something on.

Jonny and Dennis, I just happen to have the remnants from an '88 911 harness and look what I found.. all complete with the original wiring......LOL



I really would appreciate your input on how to make this work into the '71 harness.
TIA
Johan

[PeteKz]

If you have a modern radio, no need for a noise suppression cap.

[Uwon]

Originally Posted by PeteKz

If you have a modern radio, no need for a noise suppression cap.

Thanks for that info. It’s interesting that none of my four wiring diagrams appear to show a cap.
Fortunately, my music will be coming from the rear, LOL
Cheers,
Johan

[PeteKz]

I took it out of my 1973 car. I have a 4-year old radio, so it's immune to ignition noise.

[Showdown]

Hey Johan,

Not sure if it’ll be helpful but here’s the flowchart from my 77 which has intermittent wipers

[Uwon]

Thank you Julian. Very helpfull. I’ll do comparisons and some testing when I return home on Monday and see where I end up.
Cheers,
Johan