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12v constant wire dead?
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12v constant wire dead?
Could someone please help me. I recently bought at 07 f250 superduty. The stereo did not work when I got it so I went to I install a new double din. I have power coming from the acc wire but no power from the factory harness that is suppose to be constant 12 volts. Any suggestions?
Lead Driver
Joined: Feb 2011
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From: L.A. (Lower Alabama)
Not Sure if there were any changes for the '07 model year but here's the fuse layout for 2006. There are a few fusable links down the smaller wire from the passenger side battery + post.
^^^----under hood fuse panel
^^^^----under dash fuse panel
^^^----under hood fuse panel
^^^^----under dash fuse panel
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Thanks.the thing is all the fuses look good underdash and don't see one under hood for radio constant. The only thing I can think of is a short in the wire. I don't want to resort to running a wire from battery.
Lead Driver
Joined: Feb 2011
Posts: 8,241
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From: L.A. (Lower Alabama)
I would expect that wire is fused. Probably under the dash (I didn't see one labeled as radio memory). Maybe multimeter on ohms scale and beep for continuity if it has that function. Then probe the backs of all the fuses with the other lead. If you look closely, the blades of the fuses come all the way through the plastic on the tops. You won't have to pull them out to test (or trust your eyes that it's good 
). Maybe you can find one that has continuity on one blade and not the other. That would be a bad fuse or the blade is beside the clip in the fuse box and making a poor connection.
). Maybe you can find one that has continuity on one blade and not the other. That would be a bad fuse or the blade is beside the clip in the fuse box and making a poor connection.
Postmaster
Joined: Sep 2010
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From: Southern Cal
Maybe I don't understand your question but my 07 only has power or the radio on when the key is on. However, if I shut the engine or key off, it still have constant voltage to operate the radio until the door is unlocked.
Lead Driver
Joined: Feb 2011
Posts: 8,241
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From: L.A. (Lower Alabama)
Power to operate the radio system is routed through f2-11 and is also switched by the delayed acessory fuse. If I understand right he doesn't have the constant power for the radio memory (station presets and clock).
Checking the fuses is always step one, and the way I described above is quick and accurate but he may need a wiring diagram with wire colors to figure this out if the fuses are good.
Recently, I replaced both the starting batteries in my truck and the old ones where out for several hours. When I put the new ones in my clock and presets on the radio where still there. There must be a capicator or small battery in the circuit somewhere for that to happen (or the radio has a EPROM). The battery (memory) circuit may be a little more complex than I used to think.
Checking the fuses is always step one, and the way I described above is quick and accurate but he may need a wiring diagram with wire colors to figure this out if the fuses are good.
Recently, I replaced both the starting batteries in my truck and the old ones where out for several hours. When I put the new ones in my clock and presets on the radio where still there. There must be a capicator or small battery in the circuit somewhere for that to happen (or the radio has a EPROM). The battery (memory) circuit may be a little more complex than I used to think.
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I got it figured out guys. The constant wire was pinched back behind the dash. I had to do some searching but I found it. Thanks for the help and responses
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Lead Driver
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