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Splicing under the dash

lonesouth

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Dec 18, 2003
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What is the best way to splice a wire under the dash? I want to take B+(yellow wire) from the ignition switch to the radio keep alive. What is teh best way to do this? Soldering it could be problematic, I'm damn near a yoga expert after running the wiring for my tach last night.
 

DirtDonk

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Well, depending on how hidden you want to keep it, you might consider an additional power stud under the hood, with a wire straight from the battery. That way you could run all sorts of always-on accessories from it.

If you don't want to run the extra length of wire, or have additional wires under the hood, you could add a tap to the fuse block.
What year is this you're working on? Fuse panel in the glovebox, or on the floor?
I've used those plug-in taps with success before, but it's not my favorite thing to do. You could pull the fuse panel (or the whole glovebox?), pull it out and solder your power wire to the back of one of the lugs or solder joints on the back of the fuse panel without having to lay under the dash.

Since it's such a low power drain, and has a pretty non-critical function, tapping in is not such a bad thing. I just hate to see you mess with the main power feed to the ignition switch and risk messing up much more important things.

Perhaps the simplest constant power line to tap into would be the cigar lighter wire? Always on, more than enough capacity, and if it ever messes up, not a critical loss.
Easy to fix too.

Paul
 
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lonesouth

lonesouth

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Perhaps the simplest constant power line to tap into would be the cigar lighter wire? Always on, more than enough capacity, and if it ever messes up, not a critical loss.
Easy to fix too.

Paul

funny you should mention that. Just last night I checked the lighter and it had no juice. Rather than follow it to the source(looked like the light switch), I just cut it and hooked to the switched stud on the ignition switch.
 

DirtDonk

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Hah! Yeah, well sometimes plans don't go according to plan.
I'm not sure you should run the cigar lighter through the switch though. It's got it's own fuse in the panel and does pull more juice than just about anything in the dash other than the heater motor. Puts an extra load on the switch I'm thinking.

I may be overthinking it of course, but see what others have to say about that.

And did you check the fuse?

Paul
 
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lonesouth

lonesouth

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I didn't check the fuse...Maybe should have done that. Right now it is only powering my GPS, less than 1 amp. I'll check the fuse though and the undo my wiring if that is the case.
 
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lonesouth

lonesouth

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Fuse 4 looked good. I'll check the courtesy light socket for voltage.

Fuse 3 is blown, so that probably explains why I have no gauge lights.
 

71massbronco

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Mar 13, 2011
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Don't forget that a blown fuse may only be the beginning of a bigger problem. So after you replace the fuse, keep an eye on your wiring. If it blows again, it's time to hunt it down. Good luck!
 
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lonesouth

lonesouth

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After removing, inspecting and replacing fuse 4, my courtesy lights started working again, so perhaps it was just corroded. I'll check the blue wire again for voltage.
 

DirtDonk

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Often just pulling the fuses and sticking them back in will cure problems temporarily (or for a long time) so that's a good practice for a new rig, or once in awhile for one you've had for awhile.
If they look pretty well rusted though, it's probably time to get in there with some abrasive to get the metal looking more "conductive".

Paul
 

Adarcy

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May 19, 2010
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I love the search feature. This just saved me hours and a potential neck ache that comes with working begin the dash :)
 
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lonesouth

lonesouth

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here's an update.

The blue/white stripe was working again, so I hooked the power socket back to it. Also, my dimmer is now working and both the under dash and wiper cover aux lights work!
 

broncobilly72

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Nov 8, 2010
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349
I would suggest running a new wire from the battery to your radio...fusedd of course. Most guys want to add an amp later to power their new sound system and the nerw wire could be used for hooking up the new amp.
 
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