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Snaking a power wireeee through firewall

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Old 10-20-2004, 03:47 PM
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Snaking a power wireeee through firewall

I have an '02 Tacoma which I'm getting ready to install an aftermarket stereo. The install guide says I need to snake a 10ga wire directly from the battery to the radio. I'm not crazay about drilling holes in my truck...can anyone suggest an existing hole I can use?
Old 10-20-2004, 03:52 PM
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To install my amp power wire I ran from the batterie under the truck and through one of the handfull of rubber plugs you have in your floor board. You have to take your seasts out and pull up the carpet to do this. From there I would run it under the carpet and under the dash. That's one way to go that requires no drilling.
Old 10-20-2004, 04:19 PM
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You can run the wire through the existing rubber plug at the main harness under the dash in the upper corner.
Old 10-20-2004, 05:23 PM
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Originally Posted by BruceTS
You can run the wire through the existing rubber plug at the main harness under the dash in the upper corner.
where the main harness?
Old 10-20-2004, 05:42 PM
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ran mine through an existing grommet on the drivers side. didnt have to take out the carpet or seat. just had to remove a panel or two.
Old 10-20-2004, 05:54 PM
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From what it sounds we are talking about a headunit here. If that is the case it's not worth the trouble. The wire that feeds the OEM unit is stout enough for the aftermarket.
Old 10-20-2004, 07:15 PM
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Originally Posted by 4RUNR
From what it sounds we are talking about a headunit here. If that is the case it's not worth the trouble. The wire that feeds the OEM unit is stout enough for the aftermarket.
Well, that's what I thought, too. However, the instructions for this headunit (Alpine CDA-9833) specifically mention to run this wire. I'd be happy to forgo the trouble of doing this if I could get away with it...
Old 10-20-2004, 07:16 PM
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Originally Posted by 4RUNR
From what it sounds we are talking about a headunit here. If that is the case it's not worth the trouble. The wire that feeds the OEM unit is stout enough for the aftermarket.
Some of the new head units are supposed to be higher rated and require a new power to be run. If it asks for it I would install it.

Send it through the rubber plug in the top of the drivers side firewall
Old 10-20-2004, 07:20 PM
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Originally Posted by dbikeman
Some of the new head units are supposed to be higher rated and require a new power to be run. If it asks for it I would install it.

Send it through the rubber plug in the top of the drivers side firewall
Can you be a little more specific about where I can find this plug from inside the cab?
Old 10-20-2004, 07:45 PM
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Originally Posted by slk320xm
Can you be a little more specific about where I can find this plug from inside the cab?
Your best bet will be to run the wire through from the engine compartment rather than trying to push it through from under the dash. You shouldn't have much of a problem finding where the main wiring harness goes through the firewall when looking in the engine compartment. Push a couple feet of the wire through and then look for it under the dash. It will be fairly high on the firewall under the dash on the drivers side - the upper left corner when facing the front of the vehicle.

Nice head unit by the way. Should sound sweet when you're done.
Old 10-20-2004, 08:06 PM
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Originally Posted by slk320xm
Can you be a little more specific about where I can find this plug from inside the cab?
In my 2001 there's a plug right above the gas pedal area. There's nothing else running through it and I used that for my CB coax. You'll need to move the carpet out of the way to get at it. Open your engine bay and you'll see it there unless they changed something between the 01 and 02.
Old 10-20-2004, 08:32 PM
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Thanks for the suggestions. I'll take a look under the hood tomorrow & see what I can find. Sounds like there should be enough options where I won't have to get the drill out!
Old 10-20-2004, 10:52 PM
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That unit is rated 26w x 4 RMS. It is an A/B unit with ~60% efficiency. Let's assume you like your music loud for extended period of time and listen to it at 80% of maximum loudness. 0.8 loudness x (26w x 4 channels equally driven) / 13.8v / 0.6 inefficiency = roughly 10 amps total draw.

Realistically there is only a few feet of 14 or 16 gauge power wire coming from the headunit harness before it hits a power panel and feeds into a bigger cable. But lets assume the worst scenario that there is 7 feet of 16 gauge wire. That’s enough to run to the top of the battery. You are looking at less than 0.3v drop, or 2%, which falls into “good practice” when sizing cables. Why cut up a new truck, then post threads why the battery drained overnight The K.I.S.S method is the best.
Old 10-21-2004, 01:11 AM
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I never had to run a power wire for my deck. I have a high end head unit. I have run most of my power wires through the main harness hole. All the others I drilled
Old 10-21-2004, 10:30 AM
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Originally Posted by 4RUNR
That unit is rated 26w x 4 RMS. It is an A/B unit with ~60% efficiency. Let's assume you like your music loud for extended period of time and listen to it at 80% of maximum loudness. 0.8 loudness x (26w x 4 channels equally driven) / 13.8v / 0.6 inefficiency = roughly 10 amps total draw.
Unfortunately, Alpine fails to mention what the "peak" current draw of the headunit is in their specs. But, these numbers look reasonable, so maybe I won't need the direct battert wire. When I get the radio out I'll take a look at the truck's wiring harness & see if I can determine the the gage of the power wires.
Old 10-21-2004, 11:42 AM
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Tap it into the ingnition wire or the original stock deck power harness. I never installed anything of that sort.
Old 10-21-2004, 11:53 AM
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Originally Posted by slk320xm
Unfortunately, Alpine fails to mention what the "peak" current draw of the headunit is in their specs. But, these numbers look reasonable, so maybe I won't need the direct battert wire. When I get the radio out I'll take a look at the truck's wiring harness & see if I can determine the the gage of the power wires.
Peak is exactly that. It won't heat up the wire. Unless you listen to heavy metal, I doubt you will see a time average of above 5 amps, if that.
Old 10-23-2004, 12:09 PM
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I have the Alpine CDA-9815 and powered the Head unit directly from battery(I think it's called "V-drive), plenty of options to run wires, just gotta look at your firewall for holes. Personally I dont know if doing this would have made any difference at all but Alpine says you'll have higher RMS so oh well.

Last edited by 2001Millrunner; 10-23-2004 at 12:11 PM.
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