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1967 Mustang Hardtop
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Discussion Starter #1
Hey everyone. I've got a bit of an interesting wiring problem I'm trying to sort right now. My accessory fuse blew at some point within the past 2 weeks and I just figured out that was the problem, threw in another SFE14 amp fuse, and it blew right after I turned the ignition to accessory.

I think I've narrowed it down to one of two things.

A steering column/turn signal switch short since this issues has cropped up since I did a bunch of steering fiddling and rag joint replacement a few weeks ago. It'd have to be a broken TS wire I think? Grounding out on the inside of the column?

OR the loose wires that go from the firewall block connector to the back up light switch are shorting. I converted the car to a manual and haven't run the back up wires yet but the car's made it 2500 miles without any issues so I'm doubting that. But would one of those wires always be hot and would it grounding on the valve cover be the problem?

Here's what I've got so far. My manual tells me it powers the back up light, turn signals, radio, PRNDL light. The back up lights aren't wired in. The PRNDL wiring is unplugged from the where the automatic shifter was and tucked under the carpet so that shouldn't be shorting. Which leaves the radio and turn signals. Radio is powered using the stock plug but I really doubt that's the issue since the inline (added) fuse there is also fine. So I think something is shorting inside the column but I'm really not sure what the most likely culprits are.

Anybody have any insight on this one? I've had a lot of issues with the steering column in general so that's where I'm leaning.

Thanks.
 

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Disconnect the turn signal harness at the column and see if another fuse blows.

Better yet, get out your test light and with the lead on battery positive, probe both sides of where the fuse clips in. One side should do nothing as it feeds positive from the ign. switch. The other side should be the "load" side with the turn signals, etc. loading the circuit.

If it's shorted, the light will be very bright. Then disconnect the turn signal switch at the column and check it again. If you have removed the short, it'll be dim to no light. If still very bright, you haven't found the short yet.

Sent from my SM-N960U using Tapatalk
 

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One by one, unplug each circuit item that the manual states is on that circuit.
If still don't fine short & each item still unplugged, using an ohm meter, take reading at fuse from ground to circuit out of fuse. Should still read shorted (0). Trace each wire to see if it's pinched somewhere. My have a wire pinched.
I had this happen when first assembling car. I put wrong bulbs (single contacts) in my backup lights. That blew fuses..
 

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You didn't by chance run any wires on top of that convenient shelf that's above the steering column to keep them out of the way did you?

I ran my add on trunk light wire up there and couldn't figure out why I kept randomly blowing the fuse. Turns out that the wiper arm takes up nearly all that space when it sweeps and so the fuse was fine until I ran the wipers and it cut the wire insulation and shorted it out.

That was a pain to figure out since it seemed to be happening randomly. Here in Florida I have to use the wipers, or at least the washers fairly regularly so it just kept blowing the fuse and it took me a long time to put two and two together.
 

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Discussion Starter #5
Disconnected the TS switch and threw a new fuse in. Radio works not and the fuse hasn't blown so far. I went ahead and pulled the wheel just to see if there's anything amiss there and I'm not seeing any broken wires. Resistance from end to end for all 10 wires showed no sign of an internal break in the wire somewhere. That means it's likely between the fuse block and the steering column plug methinks. Unless the pin that makes contact with the keyed part of the steering hub is the issue. This car is probably due for a new switch soon but I don't think it's THE problem.


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