Burnt carpet, fried wires, what happened? (Pics)

[therotman]

I have an 80sc Targa and one day the carpet and battery cables looked fried. I figured my folded up targa top must have touched something and caused it, but now I have bigger issues.


Sometimes the car will not start. I turn the key to on and can hear the pump and all the electrical works but when I turn to start nothing happens. I found that if I move the burnt wires around the car will start. It has not died while on the road, just occasionally after driving somewhere.

What did I do? What should I do to fix it?

[cak]

What size bulbs are you running of your headlight relay kit?

From here, it looks a lot like the ring terminal on the yellow wire has corroded, leading to increased resistance which means increased heat.

[Wil Ferch]

Completely side note......

I posted on a difficult-to-find "no-start" condition..... intermittant...and found I had positive cable corrosion for at least 6 inches back from the cable clamp. Look at the similar corrosion on the cable in the pic...

Fixed it long term by cutting back and cleaning the individual strands of copper and re-taping the insulation. Needed to add a new clamp that uses screw fasteners on both sides of the clamp...would like to use OEM style "crimp" connectors as a possible future upgrade.

Sorry for the diversion...but this pic just set these thoughts in motion. Might start another thread on this....

- Wil

[GeorgeK]

Major meltdown of each wire here. Cut off the last 4 inches of every wire, and have new connectors made. Then cover this area with some non-conductive protection.
Oh, and dielectric grease is your friend, as well as a thorough checkup of the circuits, looking for fuseless loops...

[therotman]

Ok- So cut, strip and re-crimp new conectors?

Then buy a protective cover?


I don't know what a fuseless loop is- ?

[GeorgeK]

Yep.
A fuseless loop would be a circuit that is not protected by a fuse, especially anything not factory installed (radio, amp, alrm,...) plus the dash lighting, the headlights (relays only there)

[cak]

Yes, cut and reconnect.

I wouldn't just crimp, unless you've got a high quality crimper. I think the ring terminal you crimped on the yellow wire was the source of your problems (at least part of it).

The typical store-bought crimper doesn't leave you with a gas-tight connection, which means that it will collect moisture and corrosion. A 'real' crimper costs about $300, though.

A good compromise is to crimp and solder and cover with heatshrink, and then secure from vibration. Here's a nice write-up, stolen long ago before Bob Hoover removed his writings from the interweb...

http://www.dimebank.com/misc/soldered_connections.html

I use the typical store-bought terminals, but remove the plastic insulator. Crimp, then flow solder into the joint. Then cover with heat shrink. Yes, you should have put the heat shrink on the wire before you crimped You don't want to see any exposed copper when you're done.

[therotman]

Is that yellow wire not from the factory? I have only had the car a little more than a year now.

I personally installed a new raido using the factory wires so hopefully that is not the problem. There used to be an amp and an alarm that were installed by the dealer back in 1980, but I do not have records of any aftermarket ones being installed.

[cak]

Is that yellow wire not from the factory?

I would guess not, given the little "+" tag and the insulated crimp terminal. The factory wires to the positive battery terminal should be red.

If it were me, I'd trace where the yellow wire goes. If it's left over from the amp/alarm that has been removed, get rid of it. If it's still in use, clean it up as I described.

[billroth]

It does look like the wire in the Sucro relay kit that I have not installed yet.

Lawrence

[glenncof]

I'll guess the other end of that yellow wire got shorted to ground and looks aftermarket. I would not reconnect until you know where it is going and properly fused if used at all.

The appearance of the red wires is a concern also. It looks like the inner one may have overheated at one time and was repaired. The outer one looks like there are remnants of the first red failure. That bolt should be replaced also, it looks wrong.

Cover + terminal with some wheel bearing grease after repairs to prevent corrosion if alternator starts over charging. I find the little red/green discs useless.

[therotman]

Sucro relay- is that for the headlights?

The red wires fried at the same time as the yellow one. I had recently looked at the battery and there were no burn scars until the carpet fried with them.

I'm going to follow the yellow wire when my son taps a nap and post pics. I think I remember it doesn't go very far to a black box under the fuse box.

[therotman]

Ok- the yellow wire goes 12 inches to this:






Any idea what it is?



I also found this random unconected wire:

[cak]

Yup, that's what I (and billroth) guessed - it's a Sucro headlight relay upgrade. That's a fine addition to your car, but you'll want to remake that ring connector end.

You might also want to check just how much wattage you're running in your headlights, though I suspect the real cause was a "bad" crimp.

Sorry, no idea about the green wire, I'm not even certain where that is on the car.

[glenncof]

Let me just say as an electrical engineer and DIY Porsche owner, you must have some serious problem if this occurred at once.

The yellow wire may have gotten fried when the red ones did. You were drawing some SERIOUS amps to discolor the brass and burn a hole in the trunk lining.

In this case I suspect the outer red wire circuit

[therotman]

Thanks for the help guys- I lost my solder gun so I'm going to have to buy a new one.

glenncof- that scares me. What is the outer red wire circuit?

[glenncof]

I looked in my Hanyes manual under schematics for 1981. From what I see there are three red wire connected at the battery in '81. One goes to fuse 18 for clock and interior lights. Two go to the ignition switch where another red wire branches off to light switch.

The other side of ignition feeds five circuits but I suspect problem before the switch.

[Mysterytrain]

Looking back at the first picture makes me think that years of corrosion from battery acid outgassing made a mess off those connections. The big fat starter cable shows some serious corrosion a couple of inches fromthe terminal. My bet is the connectors for the red and yellow connectors were cheapo and began to rot away..making a coroded and loose connection...and high resistance. Like the others have said, cut them back or replace them. You can play it safe and measure the current draw with as you reconnect each wire.

[unclebilly]

Here is your problem... and it'f a free repair!

Clean your battery terminals and cable clamps. Just looking at the pictures they are in need of cleaning. This will solve your intermitant starting.