Question on running a 12V constant w/ inline fuse to a car stereo... (1 Viewer)

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First post...great site!

I am replacing the old aftermarket stereo with a newer one and have run into a snag. The 12V constant wire that was supplying power to the old radio was routed through the inspection light socket under the dash which I believe has shorted out. So I have chosen to go for power straight from the battery. I understand that this would require a wire to be run with an inline fuse.

My question is what gauge of wire and fuse should be used to do this properly?
 
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I think I used a 16 gauge wire and the fuse size should be listed in the owners manual. I am lacking in the electrical know how so I usually confirm what I do to my rig with one of the electricians at work.

You may be able to find the original power wire somewhere under the dash as the original was not wired through the light socket. The plug is probably just lying inside the dash.

One other hint, it's not hard to pull that dash pad and it sure makes mounting the stereo much easier

Tony
 
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I pulled the dash, made a mount and did the whole shibang. When they did the wiring for the old stereo they hacked up everything. I had it running but it would erase the memory whenever the truck was off. So I went back in to check the wiring I had done. I grabbed the old wiring harness and double checked my work. Looked good to me. Went to turn it back on and no dice. I put the DMM to work and the ACC line and ground were good but the 12V constant was a no go so I traced it back to it's source.

I'm like you Kynot62, not too much on the electrical know-how but I'm learning.
 
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When you say the 12V constant you aren't talking about the wire that runs the lights in the radio are you? Our wagons run a positive ground for dimming the dash lights if I remember correctly. This makes it a big pain in the arse when it comes to hooking a new stereo to the dimmer switch.

Hopefully a better electrician than us will chime in

Tony
 
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No, I mean the wire that would go to the yellow lead on the radio harness so that the radio has a constant supply of juice when the truck is off. Sometimes they call it the memory wire I think.

I prob. should have said that the truck is a '87 FJ60. I am pulling the wiring info. off of Car Alarm, Car Stereo, Mobile Video, and Cruise Control Info for Installers, which has been a HUGE help thus far. It's a great site for any stereo questions. The link specifically for the '87 Cruiser wiring is 1987 Toyota Landcruiser Stereo Wiring Information
 

Elbert

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I'm sure a 14 or 16 ga wire would be fine, the fuse should be located in line on the wire somewhat close to the battery. I thinke the radio MFG would have teh fuse requirments in the instructions? I would guess something pretty light.
 
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Sure sounds like running a hot wire with fuse will work just fine. Don't have to go all the way to the battery either as there are constant hot wires under the dash. And if it's just the memory wire I would match the size on the radio (or larger)

Best of luck

Tony
 
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The constant 12 volt wire is just to maintain the presets and the clock. It won't need to be very big--probably 18 gauge would work. Just be sure and fuse it at the battery end of the wire. You could also run a bypass wire around the inspection light that is causing the problems.
 
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Washington, UT. The Promised Land
 
 
I've done this for years. The only issue I have had is stereos that had back lighting that stays lit when the car is running but the stereo turned off. That creates a constnt drain on the battery. I now have a rocker switch on the dash that controls the stereo with the power source being the battery. I can turn the stereo on any time I want, with or without the key.
 
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I may try the bypass first and if that doesn't work I like the idea of having a rocker switch so that I can kill the radio whenever. Good idea man.
 

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