Wiring Meltdown!

[Dr_P_in_WV]

I just bought a 1970 Karmann Ghia couple w/autostick. The body and engine are in exceptional condition. But the ignition lock was balky. As I was turning the key to the steering-lock position, I heard sparking and smoke started coming through the lock cylinder.

It took me a couple minutes to get some tools, open the engine compartment and detach the ground strap from the battery. In the meantime, there was a lot of smoke (the sickening electrical-stuff-is-melting kind of smoke). At one point, the starter motor ran for about 20-30 seconds and then the horn came on and stayed on until I got the ground strap off.

I see no damage to the (a) fuse box, (b) wiring behind the dashboard (accessed through the trunk), or (c) wiring in the engine compartment - except as noted below. I am hoping that the damage is to the ignition system inside the steering column, and I figure on replacing the lock cylinder, the electrical switch, and the turn signal switch.

In the engine compartment, there were two cables attached to the positive terminal of the battery. One runs through the firewall; I believe this one leads to the starter motor. The other cable divides into two branches and attached so what appears to be a Bosch relay. This cable is thoroughly destroyed. I am including two photos, one showing both cables (No. 2 is the melted one) and the other showing a close up of the melted cable and the "Bosch relay" or whatever it is.

I have no idea what I should use to replace the melted cable. Buying an entire wiring harness seems like overkill. Can anyone advise me as to what gauge of wire I should use? Can anyone identify the "Bosch relay" so that I can replace it as well.

Many thanks.

[c21darrel]

The Bosch "relay" is a voltage regulator.
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[Dr_P_in_WV]

[Trylon]

As a noob having just completed a total rewire of a ‘59 coupe, my advice is to not replace any component or wire until you understand exactly where the short took place.
I just experienced one, thought I knew what caused it, replaced the fried wire, and, yep, it fried again.
It was painful and time consuming but I finally figured out the cause— a later model speedometer with different grounding characteristics. I could have replaced the wire (and other components) many times over and still have gotten the same result (smoke) had I not thought it through.
If you are not comfortable with electricity (and I suspect that is the case given that you could not identify the voltage regulator), I strongly advise you to seek out someone who is and count yourself lucky that only electrical components fried and not your car.
Good luck!
_________________
1973 Porsche 914 2.0
1959 Volkswagen Karmann Ghia
1979 Volkswagen Rabbit
1973 Volkswagen Bus
1970 MGB-GT
1962 Oldsmobile Jetfire

More tomfoolery on
The Karmann Ghia Fever YouTube Channel!

[Dr_P_in_WV]

Thanks for your good advice.

I do have a fair amount of experience with electricity, although not a lot of it with old cars - hence, as you point out, my failure to identify the voltage regulator.

All the evidence points to a faulty ignition switch as the source of the short circuit. Following your advice, I will proceed with caution and put a fuse in line with the new circuit. If I am wrong about the source of the problem, the fuse will blow instead of melting the ignition switch wiring.

Thanks again.

[Trylon]

[Dr_P_in_WV]

Wish us luck![/quote]

Good luck!

[Rome]

Dr_P, you can study the wiring diagram for your Ghia. There's one in the "Technical" section at the upper right of each page. Each factory wire that was originally in your car is shown with the same color on the diagram, as well as the wire diameter in millimeters. Diagram perspective is from above, with engine to the right and headlamps to the left. https://www.thesamba.com/vw/archives/info/wiring/70-71ghia.jpg

The voltage regulator (VR) is marked C1. The thick red wire that burned is marked "6.0" which is approx. 1/4".

Millimeter to SAE wire gauge conversion:
https://www.rembar.com/resources/american-wire-gauge-awg/

Looking at the diagram, one of the red with white stripe wires at the VR goes to the battery so that terminal is always "hot". Another red/white wire goes from the VR forward to the fusebox (component S), from there a smaller red 4 mm wire goes to the light switch (E1), and another red 4 mm wire from the light switch to the ignition switch (H). There is a black, then black with red 2.5 mm wire going from the ig switch terminal 50 to a connector, changing to a red 4 mm wire that goes back to the starter solenoid at terminal 50.

The numbers are standardized component designations for the German auto industry. Terminal 50 means "switched power to the starter" for VW, Porsche, BMW, etc. Any terminal 30 means "always hot" with battery power. Terminal 31 is "ground" and usually has a thin brown-colored wire.

This path describes the actual current flow for activating the starter. It really does go from the battery at the back of the car forwards to the fuses/ig switch, then flows right back to the rear of the car to the starter.

As Trylon mentioned, there must be an underlying cause of the short circuit. This long current flow can be trouble-free for decades, until disrupted by an incident (e.g., careless tools fall onto the terminals, poor previous repair becomes dislodged, etc) that creates the short.

[Dr_P_in_WV]

[Rome]

I hope for your sake that the big wires at the ignition switch were not shorted, though most likely they were. Easy to see from the trunk, where the main loom from the steering column- the ignition switch and turn signal switch- come out into the dash area.

You have a few choices for repair, after identifying all of the wires that were burnt- Replace the electrical portion of the ignition switch with a new one, though I think that the only currently available ones are aftermarket and are likely not as robust as original German ("OG"). The other possibility is to adapt an earlier ignition switch from a '67 or so Beetle/Ghia and mount it either on the dash face, or underneath. '66 and earlier Ghias had their ignition switch on the left side of the dash, to the left of the speedometer. Either way the earlier switch will require drilling a sizeable hole, guessing ~9/16" diameter. And you;'ll have a different key than for the doors, though it's possible to have the switch tumblers re-keyed if you know the door key code. That code can be found easily once you remove the driver's door handle.

The ignition portion of the '70 switch, per the wiring diagram, has only a few wires. Here's a shot of a genuine '67 Beetle switch on which you can see it has only 3 wires for the ignition/starter circuit- terminals 30 (always hot), 15 (ignition running) and 50 (starter activation). You could take the wires from your original harness, after being repaired, and make a jumper section for the corresponding 3 wires to reach the (new) Beetle switch, then buy a black plastic round plug to close off the original hole in the steering column's ignition location. a.marscapone gallery-

[bhartwell59]

Hey all,

I need to get a length of the 6.0 red/white stripe wire (going from the + side of the battery to the VR).

Don't think I was reading the chart conversion right... does 6.0 mm = 10 gauge?

Thanks!
_________________
'74 Zambezi green Ghia vert, autostick, 101k
'87 Jeep Wrangler, 4.2, 330k

[Starbucket]

The wire from the ign. switch to the coil is UN-fused so it is what melted and any wires next to it also may be damaged.

[runamoc]

[bhartwell59]

[runamoc]

[bhartwell59]

Cool!

One more question: do we know of a place that sells OEM auto wire?

Specifically the 6mm/10 ga. red/white stripe wire?

Thanks!
_________________
'74 Zambezi green Ghia vert, autostick, 101k
'87 Jeep Wrangler, 4.2, 330k

[runamoc]

[Dr_P_in_WV]

I am the original poster, and I thought I should report on what has happened to my Ghia. The TLDR is this: I replaced the bad wires and parts, one by one, and got the car running again.

On the driver's side, I removed the rear inside panel, the door sill plate, and the floating kick panel to expose the wiring harness. I replaced the melted wires, principally the main power wire from the voltage regulator to the front of the car. I used 8 gauge wire here, and the same size wire to connect the battery to the regulator. But that was just the start.

I found a lot of burned/melted wires behind the dash. It was hard to sort them out because the PO's wiring did not fully conform to the factory wiring diagram. I also found a lot of burned up switches that had to be replaced: ignition (of course!), turn signal, headlight switch, and emergency flasher. I also replaced the voltage regulator.

I worked in fits and starts, sometimes because I had to wait for parts and sometimes because my job and domestic responsibilities kept me out of the garage for long stretches. Finally, a few weeks ago, I got all the electrics working (except the buzzer to let you know you left the key in the ignition - it was too much trouble to replace the melted wire for that one). While I had the streering column apart, I went ahead and replaced the cracked-up steering wheel with a new one in the original stock style.

With some trepidation, I hooked up the starter motor to the battery and cranked the engine. On the third try it fired up and ran just fine, even though it had been dormant for a year. Oh boy, that felt really good.

Soon I will start work on some other stuff to get the car roadworthy (adjust valves, timing, carb; change oil, etc.).

I am embarrassed that it took me a year to get the electrics sorted. I learned a lot in the process. If I knew a year ago what I know now, I might have just put in a whole new wiring harness. That way, I could put everything together per factory spec - and avoid a lot of detective work.