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

[tirwin]

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.

[fred cook]

Originally Posted by tirwin

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.

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.

[tirwin]

Originally Posted by fred cook

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)

[tirwin]

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.

[tirwin]

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.

[Ayles]

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.

[tirwin]

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.

Many thanks!

[Ayles]

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!

[fred cook]

Originally Posted by tirwin

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.

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.

[IMR-Merlin]

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.

[tirwin]

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.

[tirwin]

Originally Posted by IMR-Merlin

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.

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.

[IMR-Merlin]

Originally Posted by tirwin

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.

[Ayles]

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.

[tirwin]

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.

[tirwin]

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.

[tirwin]

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?

[Ayles]

Originally Posted by tirwin

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.

Just confirmed I have flashing at all 4 corners.

[tirwin]

Originally Posted by Ayles

Just confirmed I have flashing at all 4 corners.

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

[IMR-Merlin]

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