Simplified Wiring Harness 1971 911S

[Flieger]

I am researching for my next round of upgrades. One thing I want to do is sort the wiring since there are so many things crossed up, not working, or working intermittently.

Can anyone provide their source for a simplified wiring harness? I have heard of some using a VW Beatle DIY harness, from Painless Performance I think. Also I am looking for any advice about the installation process.

The car has the following items that I will need to connect together properly:

H1 headlights in H4 lenses (I think- my spare bulb is in an H1 box but I have plastic lenses) with high/low beam switch and dipper
hazard flasher
turn signals F+R
brake lights
horn
windscreen wipers
kill switch
alternator light
oil pressure light
S gauges (fuel/oil level, oil pressure/temp, tachometer, speedometer)
lights for gauge faces
fuel level sender
oil pressure sender
oil level sender
oil pressure switch
oil temp sender
MFI speed switch fuel shutoff circuit
starter
single plug ignition
Bosch CDI box
cold-start squirter solenoid
MFI electric fuel pump

and I believe that is everything.

I would also like to add relays to keep the ignition switch from going out if I ever need to drive at night.

Battery is a small interstate, sealed lead-acid plate type, 33 Amp-H

[PStey]

nice but quite expensive: http://www.twinsparkracing.com/compe...iringloom.html


more economical: http://www.kabelgross.de/product_inf...7da57b1fea4fef

[Dezzmo]

You can also try here: http://www.riwire.com/

They don't list 911's but they do have quite a few 356 wiring harness's listed. I'm sure they may be able to come up with something for our cars

[Flieger]

Hmm, more expensive than I thought. Thank you for the links, though. Maybe the 904 harness.

I was looking for a more built-it-yourself harness that would not have the Porsche tax. I would only be putting in the minimum number of circuits, since this is not in any way an 'original spec' car.

I appreciate the responses.

[TRE Cup]

There are places that sell vw harness kits for around $35. but you get what you pay for !

[Grady Clay]

H1 headlights in H4 lenses (I think- my spare bulb is in an H1 box but I have plastic lenses) with high/low beam switch and dipper
hazard flasher complicated
turn signals F+R
brake lights
horn
windscreen wipers
windshield washer
kill switch two circuits necessary
alternator light
oil pressure light
S gauges (fuel/oil level, oil pressure/temp, tachometer, speedometer (electronic?))
lights for gauge faces
interior & trunk lights?
fuel level sender low fuel warning light
oil pressure sender
oil level sender
oil pressure switch
oil temp sender
MFI speed switch fuel shutoff circuit
starter
single plug ignition
Bosch CDI box
cold-start squirter solenoid
Time-Temperature switch
MFI electric fuel pump



I would make your own using original Porsche wiring from salvage harnesses. With black heat-shrink, you can make it appear original while loosing the non-desired circuits and adding what you need.

A 1971 (’70 actually) has the very standard wiring carried forward for many years. The ’69 was unique and SWB was always changing and not applicable to your ’71.

I would start with a complete harness from a ’70-’73 salvage. This will let you locate all the connections to components.

There are some necessary conventions it is worth continuing. Wire color is most important I feel. So is the interchangeability of the engine harness 14-pin connector and the 14-pin connector between the engine electrical panel and the main harness.

You want to continue with the standard ignition electrical switch, the headlight switch and the two switches on the steering column. All of these mating connectors are available as spares or can be un-soldered from salvage harnesses. Remember, these are silver-soldered.

You will also want to continue with the standard connectors for the turn signal assemblies. I would add a pair of similar connectors for new headlight wiring. Make them impossible to mis-connect with the turn signal connectors. Mount the attendant headlight relays in the normal relay mountings.

Not using the fresh air blower will simplify that mess. If you use a blower, make it off-on on high only.

Your car has the provision (or perhaps installed) the intermittent wiper delay circuits. If you want to retain (or install) the intermittent feature, use the later version that has adjustable delay.

Your ’71 has the electric fuel pump in the rear. You will want that on the front cross member. Note how the pump wiring is on a ’70.

You have an extra green wire in the main harness for the Sportomatic over-temperature indicator. Retain that for your addition of the oil pressure switch (your car is not wired for both oil light and gauge).

I would add the pair of wires for twin ignition cutoff switches (above, either side of the tach). Someday ….

I suspect you may want to maintain the brake warning light.
You might add low brake fluid warning light(s).
You certainly don’t need the seat belt light.

Remember all the grounds that are in the harness. An important feature of out cars are those ‘common ground’ studs braised onto the chassis. I would separate out the common grounds in the harness itself. They are very difficult to trouble shoot.

Starting in ’74 the main battery wire in the chassis was enlarged. The larger version will fit your chassis.

I would make the yellow starter wire one size larger. Be sure to silver solder the connections.

I think Wurth has most of the original Factory connections.

I’m sure there is more.


Whatever you do, do not remove your harness until you have the new one built, tested and test-fit to some empty shell.

Best,
Grady

[Flieger]

Wow, thank you very much Grady for the thorough response. That is just the kind of information I wanted. I will save this reply until I am ready to begin the next round of upgrades.

To clarify, this is halfway to being a racecar. I have no trunk/interior lights and no windscreen washer. I do not actually remember if the intermittent wipers are working as they are not installed on the car right now (southern California ) but I do have the motor working. I have no fresh air blower.

I have only one kill switch, mounted on the cowl. Does that still require two circuits?

The transaxle is a 911/01 Magnesium case with early AFMSX gears, 7:31 ring and pinion, and non-simplified differential. I thought that this is a mechanical speedometer, with electronics starting after a few years of 915 production. I just wanted to mention all the gauges in my post since there are illumination lights for all of them.

Thank you for your advice. I will be sure to incorporate the larger wiring, relays, and warning lights.

You have an extra green wire in the main harness for the Sportomatic over-temperature indicator. Retain that for your addition of the oil pressure switch (your car is not wired for both oil light and gauge).

I thought that the light above the alternator light on the oil temperature/pressure gauge was for low oil pressure, with the signal coming from the switch on the front of the engine. You are saying the wires coming from the switch on the engine are not going to the gauge? Or has my car been upgraded? I do not recall seeing the low oil pressure light illuminate on start-up, certainly not while driving. The bulb appears good with an intact filament. I did notice an unused connection. Can I easily connect it on my current harness?

Thanks again