CIS Harness Mystery Wire

[wcover91]

Hey everyone. I have a 1983 911sc that I am wrapping up a partial top-end rebuild on from this winter. The engine has had a full rebuild by the previous owner many years in the past by Farmers Automotive. I decided to clean up the engine harness while I have it off the engine. I have pinned it out and created the following wiring diagram.

The blue wire represents a jumper wire the previous owner or re-builder must have added into the circuit. Why would they do this? It appears they are using the constant power supply to the CDI unit to also power on the Frequency Valve and the WUR. Any ideas?

[tirwin]

Are you sure it's going between the WUR and the CDI power?

The WUR and the AAR should both get 12V. Maybe that was intended to go to the AAR? I don't see it in your diagram (which is really nice by the way).

[Pazuzu]

Originally Posted by tirwin

Are you sure it's going between the WUR and the CDI power?

The WUR and the AAR should both get 12V. Maybe that was intended to go to the AAR? I don't see it in your diagram (which is really nice by the way).

Those wires also stand out because they are red with a white stripe. The ground is bundled together with them and is (of course) brown.

[al lkosmal]

I suspect that the original switched power to the CDI and fuel pump relay is no longer working and the previous owner jumped from the warm up circuit from pin 10 of the 14 pin connector, to provide switched power to the CDI. (or vice-versa)

regards,
al

[T77911S]

the WUR, AAR and FP all get their power from the FP relay. that's T14-10

sounds like he was trying to power something that was not getting power.

the best way to attack this is to remove the jumper and see what does not work

[tirwin]

FYI... Dennis (timmy2) rebuilds the wiring harnesses. He did mine and did a great job.

[timmy2]

I’m with Al. Hack fix for a problem.

[wcover91]

Tim, you don't see the AAR because its actually on the other engine harness that connects to the 12pin instead of the 14pin. See below:




I think Al is right though. The previous owner/re-builder did some fishy stuff to the fuel pump relay. The original red relay has been removed and it has been substituted for a hacked in grey 4 pin relay!

The fuel pump also continuously runs when the car is turned to run. Sounds like I need to sort out some fuel pump relay wiring issues then see if I can remove this engine harness jumper and still have everything getting proper power.

[T77911S]

Where are you getting these drawings

You have CD POWER. And FP "cutoff" in the same box with the AFM tied to them. The AFM and FP have nothing to do with power to the CD unit.

[timmy2]

Why would the AAR be wired to the Lambda harness?
Someone really did some funky things.
AAR and WUR are supposed to be on the same circuit

[tirwin]

I agree that this looks like a hack job. The question is what should be on the same harness. WUR gets power from the 14-pin harness (via pin 30 on FP relay). It is a red/white wire. It looks like the terminal on the WUR has 2 red/white wires. The 2nd red/white wire goes over to the AAR. The AAR does not get it’s power from the 12-pin. Or at least it shouldn’t.

EDIT: Dennis posted the same thing while I was typing. This is starting to look like a Gordian knot. You are going to have to map out what you have and what it should be and then compare. Might be easier to get a new harness from Dennis.

[timmy2]

Sounds like both harnesses are changed from why is original.
Happy to provide guidance to fix what you have or replacement harnesses.

[wcover91]

Maybe I am the idiot here. The connectors for the AAR and Freq Valve look very similar. Maybe I mixed up the labels on my diagram while making these late last night. I will have to go home and check later this evening. I made these diagrams myself on excel with the harnesses sitting in from of me using a multi-meter to pin out and confirm.

And the CDI Power and Fuel Pump Cutoff box represents the white 2-pin connector under the fuse panel in the engine bay.

[timmy2]

I can provide you with wire routing for each harness if you need them.
Not until about 9pm Pacific though.

[wcover91]

Timmy, that would be really helpful to confirm that my harness is in fact wired as intended.

I'm really hoping I can just fix the fuel pump wiring abnormalities at the fuse block and then remove this extra jumper wire from the 14-pin engine harness and hopefully everything is still working.

[Pazuzu]

Originally Posted by wcover91

Maybe I am the idiot here. The connectors for the AAR and Freq Valve look very similar. Maybe I mixed up the labels on my diagram while making these late last night. I will have to go home and check later this evening. I made these diagrams myself on excel with the harnesses sitting in from of me using a multi-meter to pin out and confirm.

And the CDI Power and Fuel Pump Cutoff box represents the white 2-pin connector under the fuse panel in the engine bay.

You are corret, you mistook those two connectors. That would make sense.

The only issue is the new blue wire, which is probably there because someone severed the red/white wire between the 14 pin connector and the fuel pump relay in the front.

What is interesting is that same red/white feed also goes from the fuel pump to the OXS relay under the passenger seat, so if it's been broken somehow, then the PO also must have added some other wire to that harness...

[timmy2]

Only have time for engine harness so far.
Engine harness wire routing.

Wires from 14 pin harness with physical routing:
Pin 1 yellow- direct to starter terminal 50.
Pin 3 green/black- direct to oil temperature.
Pin 4 green /red- direct to oil pressure sender.
Pin 5 green/yellow- direct to reverse switch.
Pin 6 grey/brown- direct to reverse switch
Pin 9 green/white-direct to oil pressure switch
Pin 10 red/white- direct to AAR then to WUR then to vac switch.
Pin 11 blue-direct to alternator.
Pin 12 purple/black- direct to CDI
Pin 13 yellow/black- direct to blower motor.
Pin 14 red- direct to alternator.

T2 white connector below CDI
Red direct to CDI 6 pin
Brown/red direct to air flow switch.

CDI 6 pin:
-Green wire coax direct to distributor.
-Red to T2 connector
-purple black to 14 pin (12)
-white direct to coil positive
-Brown to coil mount & Brown/white to coil neg.

Grounds: all from alternator.
1- to blower motor
2- to AAR to WUR to VAC Switch.
3- to air flow switch.

CSV plug wiring.
Yellow and red-black direct to TTS.
Yellow/blue direct to starter terminal 16.
Large diameter red cable from alternator direct to starter

[wcover91]

Timmy,

Thanks! That helps to validate there are no further goof-ups in my diagram.

I fixed the mistake from yesterday and here are the updated diagrams:

Time to fix that fuel pump relay and remove that blue jumper wire...

[timmy2]

Looks good.