Nasty surprise

[tirwin]

Started to go for a drive the other day and no start. Started troubleshooting. No power to plugs. No power to coil. No power at CDI.

Then I found this.

Suspect that there was corrosion in the wiring and the resistance led to this.

Today I’ll repair and check around for other lurking problems.

Has anyone every seen a breakdown of the wires in the through body harness by physical location? For example, what wires are in the left side vs the right side of the engine bay.

The engine will be coming out anyway — probably this fall. I would like to compile a list so I can do some thorough testing. I’m probably going to unwrap the harness as much as I can to physically inspect.

[garment]

Glad you caught this. May I ask why your engine is coming out? I think you did a major rehab not too long ago?

Originally Posted by tirwin

Started to go for a drive the other day and no start. Started troubleshooting. No power to plugs. No power to coil. No power at CDI.

Then I found this.

Suspect that there was corrosion in the wiring and the resistance led to this.

Today I’ll repair and check around for other lurking problems.

Has anyone every seen a breakdown of the wires in the through body harness by physical location? For example, what wires are in the left side vs the right side of the engine bay.

The engine will be coming out anyway — probably this fall. I would like to compile a list so I can do some thorough testing. I’m probably going to unwrap the harness as much as I can to physically inspect.

[tirwin]

Will be doing a few projects. Main one is EFI/ITB conversion. Also replacing 5th gear with a taller (TL) gear. Suspect I have an oil leak from the pulley seal area.

[jjeffries]

It took me a while to figure that picture out ... I thought the heater trunking had gotten melted, but that's because it's a similar hue to the burnt (red) wire. Stupid question (since I am the owner of an 82) but what does that connector go to?

Glad there were no flames. Best of luck for a quality repair that gets you back on the road soon.

John

[gomezoneill]

Originally Posted by jjeffries

It took me a while to figure that picture out ... I thought the heater trunking had gotten melted, but that's because it's a similar hue to the burnt (red) wire. Stupid question (since I am the owner of an 82) but what does that connector go to?

Glad there were no flames. Best of luck for a quality repair that gets you back on the road soon.

John

Possible engine compartment blower motor.

[tirwin]

Worse than I had hoped. I keep going back further and further and can’t find good copper.

I guess the good news is this happened at home and didn’t cause a fire or leave me stranded.

Some of the brown/red wire is now exposed in places. Maybe it was the heat. Hard to tell.

I was going to try to repair and get back on the road but now it seems I don’t know just how far down the rabbit hole I will have to go. Maybe I just need to go ahead and pull the engine so I’ll have better access.

[tirwin]

Originally Posted by jjeffries

It took me a while to figure that picture out ... I thought the heater trunking had gotten melted, but that's because it's a similar hue to the burnt (red) wire. Stupid question (since I am the owner of an 82) but what does that connector go to?

Glad there were no flames. Best of luck for a quality repair that gets you back on the road soon.

John

Yea, sorry. Didn’t think about that.

I talked to Dennis yesterday. I think this is the switched power to the CDI. This is where you need two different kinds of wiring diagrams. The Bentley and the factory diagrams are handy most of the time, but at times like this I really want a physical wiring diagram.

I am taking apart the bracket on the left side and trying to take off all the wire wrap to get a good look inside the harness. Going to take a while to tag the wires and connections.

[DanielDudley]

Go check the other end of the wire. Most likely it is fried end to end.

I got a color coded wiring harness diagram from Ebay that shows the entire harness on one page, no breaks. It is quick to trace anything with your finger in seconds.

[tirwin]

I will check it out. Need to go further back. That wire goes all the way up to the front fuse panel. Checked everything else out and it seems ok. Slow going because I made notes as I went.

Is the diagram Prospero’s Garage. If so I have that one. I found a few errors on it so I don’t trust it 100%.

I am making my own diagram of how the wires lay out. Will post it when I get done.

[Uwon]

Ugh! Feel for you Tim.
Nasty for sure.
If you are looking for some colour coordinated replacement wiring, I’ve been told that Restoration Design up here in Canada has some.
Good luck.
Johan

[jjeffries]

Looks like Tim is already talking with Timmy2, aka Dennis, THE wiring hombre.

I made what I thought was a wiring repair to my SC couple of years ago (relating to fuel pump circuit and a relay therein); my diagnostic understanding was inadequate and I melted that subharness, but was supremely fortunate that that was all the harm I did. Point being, I can absolutely relate to the almost shorts-soiling feeling you get when you see damage like that.

I know you'll get it resolved just fine.

John

[tirwin]

Thanks, guys.

I was planning on redoing some of the wiring soon when I do my EFI/ITB project. I won’t need the heater blower relay any more but I am trying to keep things easily reversible. Dennis and I are discussing that too as he’s about to do the same project.

He is going to make me two extra round relay plugs. I also have a Griffith’s A/C and there is another relay in the engine bay for that. The other one will go in the front fuse panel which will be used for the oil cooler fan. I want to clean up the wiring to make it consistent.

The other thing I’m trying to decide is how much I want to do now vs later. Probably going to patch things up for now and then do the rest when I have the engine out and access is easier.

The good news is I now have peace of mind that there aren’t any other lurking issues.

[boyt911sc]

Tim,

The burnt red wire originates from the ignition switch and terminates at CDI @ 15. That’s quite a length of wire to check but you need to confirm its integrity. You might end up installing a separate RED wire and disable the burnt wire. Hopefully the damage is just this single wire.



Tony

[tirwin]

Thanks, Tony.

Red wire originates at ignition switch and then goes to fuel pump relay and then through the tunnel to the engine bay, right?

[tirwin]

Tried posting this before and it was sideways. Trying again to see if I can fix it.

I believe this is correct but it would be good to have another set of eyes on it.

F is the fused side and U is the unfused side. I also did it that way because I knew Rawknee would appreciate it.

[tirwin]

The next step is that I'm backdating the heat so I will no longer need the heater blower relay. I will terminate the wires to the test connector and to pin 86 on the heater blower relay. That relay position will stay but be unused.

Dennis is going to make me a new female round relay socket to power the A/C condenser fan (I have the dual Kuehl fender-mounted system).

For the A/C fan relay:

Pin 85 will run to ground.
Pin 86 is the trigger wire that goes to the other side of the engine bay and is connected to the Y connector to the hi/lo pressure switch.
Pin 30 goes to 12v switch power.
Pin 87 goes to the fans.

Since I no longer need the heater relay, I'm thinking I'll just reuse fuse 22 for 30 & 87.

[TwoBluPorsches]

Here's the real thrill for those who haven't figured it out yet

the red wire to the CDI is UnFused.

the power comes from battery goes through the ignition switch and direct to the CDI.

That wire could be smoked all the way up to the ignition switch.

You might think that a car with 30 fuses would have protection for everything but it doesn't.

[dhanl82]

Tim,
In reference to your post I took a look at the spare engine wiring harness that I have for my 1982 SC. After tracing the various wires and plugs, using Ohm meter, and looking at my car, it appears that the following may be correct.

The “white” connector that contains your burned wires has a red one ( term # 15 from ignition switch it goes to the top of fuse 12 then bridges to top of fuse 11 (UNFUSED) – Bentley page 970-4 - then goes to CDI unit ,switched power.

The red/brown wire in the white plug is the ground wire leading to the air plate sensor switch from term # 85 on your fuel pump relay – Bentley page 970 – 9. It appears to me that the red # 15 wire is unfused.

Hope I have all this correct.

Dave

[RDM]

That may be the ugliest wire I've ever seen. Glad you found it in a fairly harmless way.

[tirwin]

Originally Posted by TwoBluPorsches

Here's the real thrill for those who haven't figured it out yet

the red wire to the CDI is UnFused.

the power comes from battery goes through the ignition switch and direct to the CDI.

That wire could be smoked all the way up to the ignition switch.

You might think that a car with 30 fuses would have protection for everything but it doesn't.

yep. I never paid attention to that until now. I have an MSD Streetfire and it has a fused 12 AWG wire from the starter to actually drive the coil. The red wire to pin 15 is just used to power the Streetfire. My luck that is the wire that fried.