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My Ranchero
Member Joined: 07-August-2014 Location: West Kelowna Status: Offline Points: 46 |
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Posted: 25-March-2019 at 6:19AM |
'73 Ranchero. The back up fuse keeps blowing as soon as ignition is turned on. Any ideas? We know there is a short to ground but cannot locate it. Disconnected back up switch and plug to ignition switch. The ac terminal on fuse box shows short to ground which is fused through the back up fuse. Disconnected the plugs on on firewall and pulled fuse box, no signs of rust or poor connections. What else is powered through this terminal? The wiring diagram does not show the fuse box. Thanks!
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Be a part of the solution not part of the problem.
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californiajohnny
Moderator Group Joined: 05-October-2013 Location: winlock, wa Status: Offline Points: 14606 |
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ok follow the wiring for those circuits that you mentioned, with the stuff disconnected and it still blows would likely indicate a short to ground as you mentioned so more than likely it's a pinched or rubbed through spot along the wiring to them somewhere...
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JOHN
74 GRAN TORINO S&H CLONE 74 VETTE CUSTOM 90 S10 BLAZER 4X4 LIFTED 77 CELICA CUSTOM 75 V8 MONZA SUPERCHARGED 79 COURIER VERT. SLAMMED 75 VEGA V6 5 SPD 70 CHEV C10 P/U 68 MUSTANG FB CONVERSION |
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hogfiddles
Senior Member Joined: 19-September-2016 Location: Central NY Status: Offline Points: 1490 |
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I had a similar issue in my '76 Gran Torino many years ago....it was a worn wire in the steering column. A piece of shrink tubing and electrical tape solved that.
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1973 Gran Torino Sport - Q code “Q-Clone” project-on-hold
1972 Gran Torino Sport - Q code new project 1972 Gran Torino - parts 1969 Torino GT - M code 95+/- mid-80's Yamaha XJ-Series (10 trophies) |
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dave302
Senior Member Joined: 08-October-2009 Location: usa Status: Offline Points: 3171 |
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There is supposed to be a 15 amp fuse in there. The backup lamp switch fuse also feeds the windshield washer switch and the feed for the accessories.
Edited by dave302 - 26-March-2019 at 10:29PM |
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dave302
Senior Member Joined: 08-October-2009 Location: usa Status: Offline Points: 3171 |
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I have listed below what the other fuses are connected to.
fuse 1 empty fuse 2 heater fuse 3 air condition (circuit breaker) fuse 4 empty fuse 5 instrument panel & controls illumination lamps Edited by dave302 - 26-March-2019 at 1:32AM |
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dave302
Senior Member Joined: 08-October-2009 Location: usa Status: Offline Points: 3171 |
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fuse 6 courtesy lamps
fuse 7 cigar lighter fuse 8 emergency flasher and stop lamp switch fuse 9 backup light switch, windshield washer switch and accessory feed fuse 10 radio fuse 11 emission control system, warning lamps and seat belt warning system Edited by dave302 - 26-March-2019 at 10:28PM |
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72FordGTS
Admin Group GTS.org Admin Joined: 06-September-2005 Location: Ontario, Canada Status: Offline Points: 5802 |
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So if I follow you, when you've disconnected the back-up switch and the ignition switch, you're still getting the short to ground? What wiring diagram are you using. We have one here on the website:
This may also help:
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Vince
1972 Ford GTS Sportsroof - Survivor, One Family car GTS.org Admin |
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My Ranchero
Member Joined: 07-August-2014 Location: West Kelowna Status: Offline Points: 46 |
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Yes that's the diagram we are using. All wiring appears to be good. What's weird is take the fuse out for back up lights but wipers and washers still work, so power to those is before the fuse? As the wiper motor has a built in circuit breaker. Fuse blows right away when turn on ignition, car is not in reverse so it's not the back up circuit.
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Be a part of the solution not part of the problem.
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dave302
Senior Member Joined: 08-October-2009 Location: usa Status: Offline Points: 3171 |
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The windshield washer switch and the windshield wiper motor are probably powered on two different/separate circuits. Edited by dave302 - 26-March-2019 at 10:50PM |
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Big Bird
Senior Member Joined: 25-August-2013 Location: New York Status: Offline Points: 4194 |
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washer is a separate motor in the washer reservoir.
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"What we do in full frontal view, is more honest than your cleaned-up mind."
Randy 1979 T-Bird 2005 F-150 STX RCSB 4.6, 3.55 LSD How the Heck does a REGULAR CAB SHORTBED weigh over 5200 pounds? |
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72FordGTS
Admin Group GTS.org Admin Joined: 06-September-2005 Location: Ontario, Canada Status: Offline Points: 5802 |
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The wiper motor is on a separate circuit with a circuit breaker. I have the factory wiring diagram for 1972, and it shows that the seat belt warning switch, light and the parking brake light are on that circuit too. It also shows it tied into the rear window defogger switch. Maybe check the wiring over on that stuff. It shows two wires for the circuit, white/purple and black purple.
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Vince
1972 Ford GTS Sportsroof - Survivor, One Family car GTS.org Admin |
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californiajohnny
Moderator Group Joined: 05-October-2013 Location: winlock, wa Status: Offline Points: 14606 |
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ok from what you're describing, when you turn the key on it blows that fuse? ok one side will be the unfused power supply, the other side will be the fused side going to what ever accessory. if the short were in the power supply side it wound burn the wire as it's direct unfused power! but blowing that fuse tells me it in the other side going to whatever... look on the back side of the fuse box see which side is supply it will usually have a buss bar connecting several other fuse terminals. look at the opposite side of that fuse find the wire connected there, follow that wire away from the fuse box until you find a bad spot or something that's not right ! like a burnt or disfigured section of the wire coating or where a burnt wire melted into that wire from something else???
Edited by californiajohnny - 02-May-2019 at 3:02PM |
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JOHN
74 GRAN TORINO S&H CLONE 74 VETTE CUSTOM 90 S10 BLAZER 4X4 LIFTED 77 CELICA CUSTOM 75 V8 MONZA SUPERCHARGED 79 COURIER VERT. SLAMMED 75 VEGA V6 5 SPD 70 CHEV C10 P/U 68 MUSTANG FB CONVERSION |
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andrewok1
Senior Member Joined: 02-June-2015 Location: OCALA FL Status: Offline Points: 424 |
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BACK UP LIGHT WIRES & REAR BRAKE LIGHT WIRES - RUN UNDER YOUR FEET ON DRIVERS SIDE , THEN MAKE A TURN AND ARE IN THE REAR QUARTER PANEL JUST BEHIND THE THE DRIVERS DOOR , U NEED TO PULL UP THE CARPET-TO ACCESS THE WIRING HARNESS TO SEE IF YOU CAN DETERMINE IF AS SAID IN COLUMN OR REAR SECTION OF THE HARNESS ,wires run under a metal panel ,under carpet
just is that i had a simliar problem on my 72 Ranchero and it was in that area |
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GET IT GOT IT GONE !!!!!!!
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hogfiddles
Senior Member Joined: 19-September-2016 Location: Central NY Status: Offline Points: 1490 |
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The only way we found it was when the mechanic was on his back under the dash, he just happened to see the tiny arc up in the column. Dumb luck to spot that. |
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1973 Gran Torino Sport - Q code “Q-Clone” project-on-hold
1972 Gran Torino Sport - Q code new project 1972 Gran Torino - parts 1969 Torino GT - M code 95+/- mid-80's Yamaha XJ-Series (10 trophies) |
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andrewok1
Senior Member Joined: 02-June-2015 Location: OCALA FL Status: Offline Points: 424 |
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BLACK & PINK reverse circuit wires ,
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GET IT GOT IT GONE !!!!!!!
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andrewok1
Senior Member Joined: 02-June-2015 Location: OCALA FL Status: Offline Points: 424 |
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wiring under carpet/but normally under metal chase
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GET IT GOT IT GONE !!!!!!!
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