12v constant wire? (fuse??)

well i think ive tracked my problem down for my 1986 olds ciera, the 12v constant doesnt work and hasnt in afew years. (no cig lighter, no interior light, no radio memory) which i dont care as, i dont smoke (nor is anyone allowed to smoke in the car), and ive gotten use to not having an interior light as its completely blown apart (the bulb holder is in 2 peices and burned) but the radio problem has been annoying me. so im wanting to run new wire straight from the battery to the radio. but i need a fuse, but what size? should i use a fusable link or an inline fuse holder, also should i mount this in the engine bay or behind the radio?

as far as i know the car has been in an accident and been rebuilt so the wire maybe got sheared off or something (or a fusable link or something blew) but theres nothing in the fuse box that links to the 12v constant.


so what size fuse and of what kind? (also what size wire?)

You can use 10awg with maybe a 50 amp inline fuse in the engine bay by the battery
That's a little excessive, but it will get the job done

This would run to the yellow wire on the headunit, you'd still need a switched 12v wire which you should be able to find in the dash somewhere (maybe) with a DMM.

There's only one problem with that logic sr20. If you use 10 guage wire and a 50 amp fuse the wire's insulation will melt long before the fuse blows. And not to mention that you will fry your headunit if 50A run through it. Most car makers use a 15A fuse for the radio and cigar lighter combined. Recommend using nothing above 15 maybe at the extreme highest 20A and a inline fuse holder that holds Maxi style fuses, put it close to the battery that way you won't have to remove your radio if the fuse blows.

50a wont melt a 10ga wire. you are pushing it but i wont melt it.

Id say stick with 10ga and run a 25a fuse.

15A fuse and 16ga wire is plenty for a cd player.

There's only one problem with that logic sr20. If you use 10 guage wire and a 50 amp fuse the wire's insulation will melt long before the fuse blows. And not to mention that you will fry your headunit if 50A run through it.
No it won't, 10awg can take 50 amps all day long
The headunit shouldn't draw 50 amps, you're right, but there's nothing wrong with using a wire and fuse capable of delivering 50 amps.

you won't find the blown fuse for const 12V under the dash .... it will be a fuse under the hood. Look to where the alternator power wire goes ... it should go to the fuse box if you still have the factory alternator. One of those fuses will be blown.

well ive looked in the manual for my stereo and it says to use AWG18 on any wires. and i contacted kenwood through email and they say it doesnt need to be a fused wire as theres on on the back of the unit.

that all seem right? or is kenwood a bunch of idiots?

well ive looked in the manual for my stereo and it says to use AWG18 on any wires. and i contacted kenwood through email and they say it doesnt need to be a fused wire as theres on on the back of the unit.

that all seem right? or is kenwood a bunch of idiots?

It needs to be fused at the battery to protect the car in case the wire shorts out, so that it doesn't melt down and light the car on fire.

As for the 18awg, that's for the output running to the speakers, not the power input. The wire running to the radio stock is normally 12-16awg, nothing wrong with going larger.

so go with a 15A fuse, with 10AWG wire?

(cause as soon as it gets to the stereo its down to 18AWG wire) and my stereo only takes 10amps (from the manual)

Like i said, a 15a fuse and 16ga wire.

Like bjboertje said 16 ga would be proper for this installation 10 ga would be way over kill.

ok, i went out to the local lordco and got an inline fuse holder its now wired to be 6 inches away from my positive on my battery with 25 feet of 16g wired up (the smallest roll i could get, and its better to have more then is needed) then the heavens decided to open up and pour down on me in my driveway so i packed everything up and headed inside with my head unit and its mess of wires (going to get that all wired up perminently because right now its just done to check if it all works.)

tomorrow or later today is going to be fun as i have to find a grommet in my firewall that i can fish the wire through.

(anyone know of a spot on a 1986 oldsmobile cutlass ciera?)

EDIT: i found one but its on the other side of the engine compartment (looks to be the only one too)...this is going to be so fun... :(

i drill andgrommet all my own holes.

the wire is in, the fuse is in (weather tight inline spade fuse, 10amp) and its all wired up for good, and man does it sound great!

i ended up going with the 10amp fuse as if i went with the 15 i would be replacing the mini fuse in the back of the stereo if it ever blew. i ended up finding another grommet on the driver side above the pedals that i was able to run it through and snake it all though my dash (there acually was a straight oening from the grommet to the back of the stereo opening (lucky me)

thanks for all your help.

i ended up going with the 10amp fuse as if i went with the 15 i would be replacing the mini fuse in the back of the stereo if it ever blew. i ended up finding another grommet on the driver side above the pedals that i was able to run it through and snake it all though my dash (there acually was a straight oening from the grommet to the back of the stereo opening (lucky me)

Those fuses are for different purposes. The one on the back of the headunit should only blow if there's a malfunction, to protect the headunit from further damage. The one in the power wire is to protect the car in case there's a short, so the wire doesn't melt down and light the car on fire. There's no reason to use a smaller fuse in the power wire than on the headunit.