Need some help sorting out fuse panel wiring -'83 SC
 

Folks,

I could use some help sorting out some wiring. About a year ago I swapped out my front fuse panel to Fred Cook's ATO style. Everything was working, or so I thought. At the time, I just did a 1:1 conversion of the wiring.

While trying to get my A/C working yesterday, we discovered that the evap fan circuit didn't have 12V. It appears as though some PO had changed some things trying to get the A/C to work. Now I get to sort it out. :roll eyes:

It looks like I have most things sorted out but I currently have 3 groups of wires that I can't figure out and the car won't start. That could be because I've had stuff on today testing and I ran the battery down, but I don't think so. It still sounds like it's cranking hard.

I think one of these has something to do with the fuel pump circuit -- maybe the tach cut-out or they are the remnants of an alarm?

Group #1: red/black & red/white wires in a pair EDIT: SOLVED. Constant hot needs to connect to power window relay pins 86 (red/white) and 30 (red/black)

Group #2: black & black/red (can't find this at all in any wiring diagram)

Group #3: red

All 3 are in the end of the fuse panel near the fuel pump relay.

Any ideas?

Here is my spreadsheet I made to document everything. The color codes in the "Fuse #" column show which fuses are 'bridged' together.

http://forums.pelicanparts.com/uploa...1436753713.jpg

SC Wiring..........
 

Tirwin,

Do you have the red wire running from fuse 11 to fuse 16? That is the power feed wire for the fuel pump relay. If not, may be why the car won't start.

Not sure about the black and black/red. I don't have it on my wiring info either. If possible, you may have to try to trace them back to their source.

On my SC, I put the front condenser fan on fuse 19 and the evaporator fan on fuse 20. Each of these fuse positions should have +12v feeding the top side of the fuses. The two a/c fans were the only load that exceeded 20 amps on my fuse panel. Hope this helps.

Fred C.

Thanks for the help, Fred.

Yes, I have fuse 11 to 16 jumper. I also just tried removing the fuel pump relay and jumping the pins to make sure the fuel pump runs with the switch ON and it does, so I think I have that wired correctly.

Fuse 19 on my car is the headlight washer system (which has never worked as far as I know) but just in case I ever want to use it for it's original purpose, I decided to move the front A/C condenser fan relay from it's original position to extra fuse position A.

Fuses 11, 12 & 16 should be bridged. (HOT IN RUN OR START)

Fuses 13, 14, 15 & C should be bridged. (HOT IN ACC OR RUN)

Fuses 17, 18, 19, 20, A & B should be bridged. (CONSTANT HOT)

The black wire that is in the pair with the black red wire goes into a wire bundle. The other wire in the bundle is red/white wire on the BOTTOM of fuse #20 which goes to the evaporator fan relay.

I think that means the black wire should go from HOT IN RUN OR START to pin 85 in the A/C relay. I'll go test that for continuity.

I have been pouring over wiring diagrams until I can't see straight.

I have the color wiring diagram from Prospero's Garage aka colorwiringdiagrams.com -- unfortunately it has several errors.

- It skips fuse #12.

- There is a fuse #22 that doesn't exist.

I found a few more but I can't remember what they were now.

I have a suspicion that the black & black/red wires actually go to the fuse panel in the engine bay. I am going to test that theory tomorrow. I think at least one of them may go to the Heater Blower Relay on pin 86.

There are only a handful of black/red wires in the wiring diagrams and I don't think they make any sense why they would be connected to the fuse panel directly.

It's late and my brain is fried.

I believe there is a black/red wire that goes from the fuse panel to the factory alarm.

In between the blue and red fuse on the image below.

http://forums.pelicanparts.com/uploa...1436765796.jpg

Ayles, that is great!

A couple of questions -- do you have the factory alarm? If so is it bypassed/disabled or working? That looks like a dead-end connection but I just wanted to make sure I'm not missing something.

The next time I'm in Bellevue/Redmond I'll buy you a beer if you take a couple of pics that show the top row of your fuse panel up close.http://forums.pelicanparts.com/support/smileys/wat6.gif

Many thanks!

I have the factory alarm and it's currently bypassed with jumpers. I don't have an alarm key or know if it works so I bypassed it as way to eliminate variables during my recent trouble shooting. My car has a few stray wires left dangling by a po that are possibly causing my no start condition as well...

I'll grab some pics when I get home from work tomorrow.

Sounds good on the beer!

Fuses
 

Fuses number 22-24 are in the engine compartment. They normally power the rear window heater and heater relay. One of the 3 is usually not used.

I am sorting out my wiring on my 79. Someone put a fuel shut off switch hidden under the dash and who ever did the engine rebuild never found it. So they hot wired the fuel pump with no relay. So I am digging into the relay now. So frustrating.

After digging into the factory harness on this 79, I am glad I did a painless harness for my 82 930.

Fred,

You are absolutely right. What I was referring to was the color wiring diagram I have. They skip #12 in their numbering of the front fuse panel so they end up with 22 instead of 21.

Another confusing thing they do in the diagram is the convention changes. At one end of the front fuse panel diagram they show the top wires on the left and the bottom wires on the right. Ok, that's fine. But then somewhere in the middle they change the convention so that the bottom wires are shown on the left and the top wires are shown on the right.

The headlight washer system is completely omitted from their diagram and so is something else -- I believe it is the sunroof motor.

Overall, it's a helpful reference -- and a great idea -- but when you're trying to troubleshoot something and you start finding mistakes, it starts to make you wonder whether you can trust the rest of it. I had to do a lot of comparison to the wiring diagrams in the Bentley.

It is always something, right? I'm headed to the garage for a while to try to figure the rest of this out. I'll keep everyone posted.

Ayles is going to post pics later of his RoW car.

Can someone with a US '83 please post a couple of close-up pics of your (mostly) original fuse panel wiring so we can see any differences. I'll update my spreadsheet and then post it when I'm done so maybe it will help others in the future.

You can say that again. I have an extensive 12v electronics background and ran a race shop for a while. the biggest PITA is electrical issues that someone else "fixed" first.

To be clear my car is US with a big port ROW engine. This is as I got the car minus the AC harness. I still have three or four stray wires. Maybe we can figure those out once we get Tirwin squared away. :)

Just snapped these pics. From left to right. Just got a set of fuses to put in since mine are of unknown age and condition.http://forums.pelicanparts.com/uploa...1436834971.jpg

http://forums.pelicanparts.com/uploa...1436834992.jpg

http://forums.pelicanparts.com/uploa...1436835020.jpg

http://forums.pelicanparts.com/uploa...1436835040.jpg

Thanks for the clarification, Ayles. I just saw ROW in your sig and "assumed".

I am working through this. Not making much progress. I have been able to conclusively trace out some wires, but there are so many discrepancies between what seems to be in reality and what is in wiring diagrams.

Ok, question about hazard light function.

Are the rear brake lights supposed to flash when the hazard lights are on? I have one that is flashing and one that is not.

Someone please verify my thinking. It looks to me like:

Fuses 11, 12 & 16 are bridged together and get power when RUNNING or STARTING. I am having trouble verify what color and how many wires connect to these fuses. It looks like (2) RED, a BLACK/RED, a RED/BLACK and a RED/WHITE come together on #11 & #12. One of the two RED wires is a jumper over to fuse #16.

Is this right?

Just confirmed I have flashing at all 4 corners.

Just to clarify... neither of your brake lights flash, right?

tirwin, do you have a powerprobe? I can not praise this tool enough for chasing wiring issues.

my brake lights do not flash with hazards or turn signals on my '83.

I did run into a similar issue though where my right front signal would light up when I applied the brakes. Turned out to be a case of a single filament bulb inserted in one of the sockets that required a two filament bulb. The single contact on the bottom of the bulb was basically touching both prongs in the socket.

So check all parking, brake, and turn signal bulbs and make sure they match what the sockets are.

Oh... I don't know if it's brakes or turn signals...

I do have lights flashing at all four corners of the car when I activate the emergency flasher switch.

No, but I may pick one up.

If it's the corners then it's the turn signals.

This is a really minor thing, but I discovered in the process of troubleshooting this odd behavior. I haven't touched these wires, so it must be an old problem and I never noticed it until now.

HAZARDS ON - LEFT SIDE
Front parking light - blink correct
Front side marker light - no blink correct

Rear parking light - blink correct
Rear side marker light - no blink correct

HAZARDS ON - RIGHT SIDE
Front parking light - no blink wrong
Front side marker light - blink wrong
H4 city light - blink wrong

Rear parking light - blink correct
Rear side marker light - no blink correct
Brake light wrong

Here is a good write up of the emergency switch. Mike maybe someone you want to reach out. He has helped me with a few things in the past.

http://forums.pelicanparts.com/porsche-911-technical-forum/857540-understanding-emergency-flasher-switch.html

Hi Tim! Hoping I can contribute a little for all the times you've made me pee my pants laughing with your wit. SmileWavy

I have the red/black wire labeled as hazard flashers both top and bottom of fuse 17, and I don't believe I have any plain black wires on the top side of the panel. Plain black on the bottom side are rear window defog and fresh air blower (fuse 12), and cruise control (fuse 15), and trunk light (fuse 18), and power window relay (fuse 21.)

I found a few things not on Fred's diagram that were on the bentley diagrams or in the owners manual, these were as follows: NOTE, there are other connections to these fuses as well, these are just the extras I had written in.

Flasher relay (fuse 11)
Cig lighter (fuse 13)
Sunroof, rear wiper (if installed) and power mirrors (fuse 14)
Brake lights and cruise (fuse 15)
Hazards (fuse 17)

Here is a pic of my old panel before I rewired it, US 1981 SC. maybe this helps?

http://forums.pelicanparts.com/uploa...1436903264.jpg


And a little plug for Fred, these panels are really nicely made and now my wiring is neat, fused correctly and safe! So glad I installed one of Fred's panels-- my car was a fire waiting to happen. A/C fans were direct to hot, no fuses and the condensor fan was melted into a blob!

http://forums.pelicanparts.com/uploa...1423840895.jpg

That is fanstastic! Thank you very much!

I'm hoping to get back to troubleshooting in a little while.

So here is something else to humor you.

I was working late last night or sorting this wiring and while I was inspecting the fuse panel I kept hearing this loud ZZZZTTT sound. The first time it happened I was touching something so my first reaction was I had some kind of short. Then I kept hearing it but I wasn't touching anything.

ZZZZTTT!!!

ZZZZTTT!!!

I started hunting all over the car looking for where the sound was coming from.

Then I realized it wasn't coming FROM the car, it was just NEAR the car. I traced it further to a stack of boxes. ZZZTTT!!! It was getting louder.

Then I saw this little guy. It's a cicada. Think of a fly on steroids. It's body is a little bigger than a walnut. He got his wing stuck to a piece of shipping tape on the box and he was flopping all over the place mad as hell. :D

http://forums.pelicanparts.com/uploa...1436906369.jpg

I learned something.

The power window relay has to be in place for the horn to work.

Hi,
Not sure if this will help - it is 1983 SC Cabriolet, should be all original wiring:(model for Japan - should be same as US)

http://forums.pelicanparts.com/uploa...1436935863.jpg

http://forums.pelicanparts.com/uploa...1436935886.jpg

http://forums.pelicanparts.com/uploa...1436935909.jpg

http://forums.pelicanparts.com/uploa...1436935926.jpg

Thanks, hotaru! That is very helpful too.

So, the only black/red wire I've seen is in the pic that Ayles posted. I will have to go back and look again at the wiring diagrams but I only saw a couple of black/red wire references and I don't think any connected to the fuse panel. I'll have to trace it out and see where it goes.

I've traced out a labelled most of the wires that I was confused about. There were some connections hidden behind the panel that I wasn't sure about.

When I was running the new A/C hoses the other day I found what appeared to be an alarm siren in the belly pan. Not sure if it was original or aftermarket but I don't think there are any other remnants left. I'll have to look up some threads on alarm systems to see what might be involved.

Hello, Tim. I followed your chart, which is great, and have the same problem - no spark. How did you end up resolving this? Thanks.

Help
 

Hey. Ok, since I got no response, I decided to go ahead and start all over again. The car starts right up now, but keeps running after I switch it off, until it runs out of gas because the fuel pump stops when the key is in off position.

Sooooooo..... I think the ignition is getting a 12 volt feed with the key off. I can’t figure out which wire in the frunk fuse box is the culprit. Any ideas?

Thanks!