914World.com > Burned wiring harness

Olympic 914

Jul 11 2017, 10:30 AM

Took the car for a drive yesterday, and it quit twice on me. First time as I was driving along and decided to turn on the heater blower fan. it just cut out and coasted to a stop. fortunately on a local neighborhood road with little traffic. after a bit of fiddling the relays and the 12 pin plug on the relay plate the fuel pump buzzed and it started. Drove to the gas station for gas and made another stop without a problem, then at a friends house again it wouldn't start. more fiddling and it started and I drove it home.

Today I start to look at things and working on why the heater blower wasn't working and the problem with the fuel pump started again. With the key on I was wiggling the relays when I noticed smoke leaking out from the 12 pin wiring harness, I quickly shut of the key and found that the black/purple wire had melted. this wire goes to the neg coil and was melted over there too. it is for the tach . maybe the points were closed when I was messing with it. the bottom of the relay plate seems ok but I haven't run any tests on it yet.

Look like I am in for a new ignition harness at least, and I don't know if it destroyed the tach. or if the problem is in the relay plate.

I was really working hard to get this thing running to take it to the Pittsburgh Vintage Gran Prix this weekend.... Looks like it won't happen now..

I put about 15 miles on yesterday and it ran great. Just staying local. I had an alignment scheduled for tomorrow but that won't happen now either.

SHIT. !!!!

vw_porsche

Jul 11 2017, 11:00 AM

Check the grounding strap from the transmission to body.
It might be trying to ground through that harness.

IronHillRestorations

Jul 11 2017, 11:17 AM

Did you unplug the 12 pin before this happened?

Olympic 914

Jul 11 2017, 02:43 PM

QUOTE(Perry Kiehl @ Jul 11 2017, 01:17 PM)

Did you unplug the 12 pin before this happened?

Yes, but not with the ignition on.

Bartlett 914

Jul 11 2017, 03:15 PM

I think this happened to me once. I think I mistakenly plugged in the 12 pin connector off by one pin. It burned a wire. I simply repaired the wire. S__T happenes

Olympic 914

Jul 11 2017, 05:10 PM

QUOTE(Bartlett 914 @ Jul 11 2017, 05:15 PM)

I think this happened to me once. I think I mistakenly plugged in the 12 pin connector off by one pin. It burned a wire. I simply repaired the wire. S__T happenes

That may have been what happened. the wire on pin 5 is the one that burned and it goes to the coil neg. pin 7 is power to the coil. if I plugged it in one pin off and the points were closed that would feed power to the pin 5 and short it out.

I should dissect the harness and inspect for any damage to the other wires.

Probably a new ignition harness should be sourced.

Click to view attachment

Also I have an extra wire that doesn't show on this diagram. its a green / black and in pin 3

Some research shows that '71 had this wire and its for oil temp. in my relay plate it does nothing.

xperu

Jul 11 2017, 05:53 PM

QUOTE(Olympic 914 @ Jul 11 2017, 11:30 AM)

Took the car for a drive yesterday, and it quit twice on me. First time as I was driving along and decided to turn on the heater blower fan. it just cut out and coasted to a stop. fortunately on a local neighborhood road with little traffic. after a bit of fiddling the relays and the 12 pin plug on the relay plate the fuel pump buzzed and it started. Drove to the gas station for gas and made another stop without a problem, then at a friends house again it wouldn't start. more fiddling and it started and I drove it home.

Today I start to look at things and working on why the heater blower wasn't working and the problem with the fuel pump started again. With the key on I was wiggling the relays when I noticed smoke leaking out from the 12 pin wiring harness, I quickly shut of the key and found that the black/purple wire had melted. this wire goes to the neg coil and was melted over there too. it is for the tach . maybe the points were closed when I was messing with it. the bottom of the relay plate seems ok but I haven't run any tests on it yet.

Look like I am in for a new ignition harness at least, and I don't know if it destroyed the tach. or if the problem is in the relay plate.

I was told that installing your license plate light wiring incorrectly/swapped can fry your harness. Mike Kelly
I was really working hard to get this thing running to take it to the Pittsburgh Vintage Gran Prix this weekend.... Looks like it won't happen now..

I put about 15 miles on yesterday and it ran great. Just staying local. I had an alignment scheduled for tomorrow but that won't happen now either.

SHIT. !!!!

IronHillRestorations

Jul 11 2017, 09:32 PM

There's a reason I asked, and it's from experience. I too plugged in a engine harness wrong. On a customer car, a very long time ago. Fortunately it was a carb'd engine so it was easier to swap.

You can get a new one from Jeff Bowlsby.

IronHillRestorations

Jul 11 2017, 09:32 PM

There's a reason I asked, and it's from experience. I too plugged in a engine harness wrong. On a customer car, a very long time ago. Fortunately it was a carb'd engine so it was easier to swap.

You can get a new one from Jeff Bowlsby.