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20 amp fuse blowing


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Just had the car out for a drive and noticed my console clock stopped working. Checked and fuse #7 (20amp), according to the owners manual, was blown so I replaced it and the new one popped instantly. Started looking and the horn is also on that circuit and not working. I know it is a constant power circuit so I unplugged the clock and horns up front, tried again and blew another fuse. Any ideas on where to look and what about bypassing the fuse? Gotta love electrical issues! Thanks.

 

Marty

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Marty, Go to the top of this page select data, then 73 wiring diagram. There are 2 20 Amp fuses listed next to a drawing of the fuse block. The Schematic shows F4 powers the clock, F3 powers the horns and lighter, F7 powers blower motor and AC clutch. What else, if anything doesn't work?

 

Chuck

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Marty, Go to the top of this page select data, then 73 wiring diagram. There are 2 20 Amp fuses listed next to a drawing of the fuse block. The Schematic shows F4 powers the clock, F3 powers the horns and lighter, F7 powers blower motor and AC clutch. What else, if anything doesn't work?

 

Chuck

 

Thanks Chuck, according to that fuse box in the wiring guide, it's fuse #1 that blowing (different fuse layout then I have). The cig lighter and horn aren't working and the console clock. I've checked about everything else and all seems well to include blower motor. Don't have AC. The only electrical work I've done in the last couple of weeks was replace the original bootcap cover for one of the wires on the pos side of my coil for an eyelet one to use with the nut that came with my accel coil. The bootcap kept slipping causing the car to stall.

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Marty, Does the car have the convenience group (seat back release relays, under hood light, etc)? If it is F1 as shown on the schematic, find F1 and wire 297 and 296. I've traced the path from end to end. Nothing I see explains why the clock and horns don't work. They did work before, right.:) Does the radio, fuel gauge, flashers, and seat back relays (if you have them) work?

 

Chuck

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Figured it out at last, I finally turned on the headlights in the garage and found that the front right side marker light wasn't on. Pulled the bulb, cleaned it and it came back on. I'm guessing that it was shorting in the socket and blowing the fuse. Horn works now, but the clock got fried. So now I'm looking for a clock!


Marty, Does the car have the convenience group (seat back release relays, under hood light, etc)? If it is F1 as shown on the schematic, find F1 and wire 297 and 296. I've traced the path from end to end. Nothing I see explains why the clock and horns don't work. They did work before, right.:) Does the radio, fuel gauge, flashers, and seat back relays (if you have them) work?

 

Chuck

 

Thanks for the help Chuck, I owe you a beer or two.

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I'm glad you found the problem and it was an easy fix. The light you mentioned is powered by F4. The horns are powered by F3, according to the schematic. Perhaps Ford did a wiring change that doesn't show up on the version posted. Lord knows they made LOTS of changes in 1972, it's a long story. Sorry I wasn't able to help much, but I'll still accept the beer.

 

Chuck

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If it was a direct short to chassis ground then the 20A fuse could have easily blown.

Steve

 

[button=http://www.7173mustangs.com/thread-1972-mach-1--1800]The Stable[/button]

 

25yvyp3.jpg

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If it was a direct short to chassis ground then the 20A fuse could have easily blown.

 

re-read my post, steve.

 

Ah, yeah, I feel kinda dumb now...the bulb itself could not cause a short, you're right. I was thinking you were referring to the plug...sorry Don!

Steve

 

[button=http://www.7173mustangs.com/thread-1972-mach-1--1800]The Stable[/button]

 

25yvyp3.jpg

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If it was a direct short to chassis ground then the 20A fuse could have easily blown.

 

re-read my post, steve.

 

Ah, yeah, I feel kinda dumb now...the bulb itself could not cause a short, you're right. I was thinking you were referring to the plug...sorry Don!

 

No prob, my whole point was...I don't think his problem is solved. there may be a bare wire that he moved by accident just enough to stop the short temporarily.

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