Running Wires

[ravig292]

2000 Ls400

I am installing a 10" sub and a 1000 watt amp

i want to run 8 gauge wires from the battery to the trunk.

what is the best way to this?

i was thinking under the car but i would rather run them from the inside.

[RDM]

2000 Ls400

I am installing a 10" sub and a 1000 watt amp

i want to run 8 gauge wires from the battery to the trunk.

what is the best way to this?

i was thinking under the car but i would rather run them from the inside.

Under the car is a horrible idea. Moving parts, hot exhaust, and road debris are just the start of possible issues.

Run it inside. Usually the hood release cable is a good spot to go through the firewall, run it underneath the sill plates but as far away from OE wiring as possible to keep out any EMI.

[1990LS400]

Under the car is a horrible idea. Moving parts, hot exhaust, and road debris are just the start of possible issues.

My wonderful mechanic Fred, formerly with the local Lexus dealer before he went out on his own and who has been maintaining our Lexus and Toyota vehicles for the past 14 years, thinks that under the car is the best way to run a wire from the trunk to the battery. He ran the power wire for my trailer light wires out of the trunk through an existing ABS wire hole and wire-tied the trailer light wire to other wires running under the car. He told me that the OEM wires he tied my trailer light power wire to are in some sort of channel under the car -- I can't see them when I look under the car. Maybe "EMI" could be a problem but many others have run amp power wires under the car with no problems.

Why do you need a 1000 watt amp? The 280 watt Nakamichi amp and rear deck sub that came in my 2000 LS400 puts out so much bass I can feel it through the seats and steering wheel and it gives me a headache if I turn the volume up more than half way.

That said, attached is a photo of the engine compartment terminal where my trailer light power wire is attached -- might work for you.

[RDM]

There is a plastic channel under the car by the frame rail that covers the fuel and brake lines, but there is no wiring harness running fore/aft under the car. I assure you, I've been under mine a dozen times and parted out another one, fully stripping it to a shell then cutting the shell up for scrap. If your mechanic likes that option, cool, but it's just way more clean, safe, and easy to go inside.

[1990LS400]

There is a plastic channel under the car by the frame rail that covers the fuel and brake lines, but there is no wiring harness running fore/aft under the car. I assure you, I've been under mine a dozen times and parted out another one, fully stripping it to a shell then cutting the shell up for scrap. If your mechanic likes that option, cool, but it's just way more clean, safe, and easy to go inside.

I have also run wires from the trunk forward to the dash through the interior of my 2000 LS400 although I did not punch through and run the wires into the engine compartment. I certainly don't rate removing the rear seat, door threshhold trim, kick moldings, dash components as being in any way "easy" or quick. Of course, I took the time to run the wires through the interior with all the other OEM wires -- I didn't do some sort of "quick and dirty" job. What's your secret, RDM?

[kjlegend13]

First off if you are running a TRUE 1000 watt amp with 8 gauge wire, that is a BAD idea! For a 1000 watt amp you will need at least 4 gauge wire.

As for running the wires, you should not run the wires under the car because of risk of fire. You are using that one wire to draw 40-60 amps from your battery to your trunk, you think you want that grounding out if it gets cut?!? NO!

That is why ANY car audio shop will tell you to run the wires through the firewall and under the door sills into the trunk. You dont need to remove the rear seats. Just slide it through the cracks, pretty simple. Removing the door sills is also not very hard, just be careful as not to crack the plastic of course. The hardest part of this all is finding the spot in the firewall to run the power wire through.

Good luck.

1990LS400, you might want to consider researching this topic before jumping all over RDM as he obviously knows what he is talking about with regards to car audio. The picture you posted will NOT do for a 1000 watt car audio setup, there is too much resistance for that much amperage being drawn from for a 1000 watt system. It must be connected directly to the battery. Period. (Not trying to be rude of course) :)

[VBdenny]

Whoa, who actually needs so much power that they need to run 4 gauge wire? You all have a difference of opinion is all. If it was me and it was easier, I'd run it under the car. If it wears out, well so what, run more. I think having all that subwoofer would probably prhobit me from replacing it if it did wear out.

It's not a perfect world but it ain't bad.

[1990LS400]

As for running the wires, you should not run the wires under the car because of risk of fire. You are using that one wire to draw 40-60 amps from your battery to your trunk, you think you want that grounding out if it gets cut?!? NO!

There is no risk of fire. Use an in-line fuse like my Lexus mechanic did when he ran the power wire underneath my car and put the in-line fuse near the battery or under the engine compartment fuse box for convenience in case it ever blows.

If there are "cracks" to slide wires through to the trunk in a 2000 LS400, I couldn't find them. The gas tank is between the rear seat back and the trunk and there are one or two forgot how many) existing holes plugged with rubber grommets on either side of the gas tank -- the seat back has to removed to access these exiting holes.

[RDM]

I have also run wires from the trunk forward to the dash through the interior of my 2000 LS400 although I did not punch through and run the wires into the engine compartment. I certainly don't rate removing the rear seat, door threshhold trim, kick moldings, dash components as being in any way "easy" or quick. Of course, I took the time to run the wires through the interior with all the other OEM wires -- I didn't do some sort of "quick and dirty" job. What's your secret, RDM?

I don't do 'quick and dirty jobs' either. I don't know why you suggested I did, or do. I've been doing car audio for over 20 years, back long ago I was certified with the MECP for Installer, Installer First Class, and Alarm Specialist. We're trained to run wires inside the cabin. I don't just throw random ideas out without fact behind them. The rear seat is removed in less than 2 minutes by anyone qualified, 3 minutes if you're a novice. The kick panels and Bpillar lower trim all snap off. It's a very simple job to disassemble one side of the car to run a wire, and again you want to run it away from the OE harness, which is actually sitting flat on the floorboard, so there's no need to pull anything else. No dash components save the lower trim under the driverside has to be removed to drop a wire down through the grommet where the hood release sits.

First off if you are running a TRUE 1000 watt amp with 8 gauge wire, that is a BAD idea! For a 1000 watt amp you will need at least 4 gauge wire.

As for running the wires, you should not run the wires under the car because of risk of fire. You are using that one wire to draw 40-60 amps from your battery to your trunk, you think you want that grounding out if it gets cut?!? NO!

That is why ANY car audio shop will tell you to run the wires through the firewall and under the door sills into the trunk. You dont need to remove the rear seats. Just slide it through the cracks, pretty simple. Removing the door sills is also not very hard, just be careful as not to crack the plastic of course. The hardest part of this all is finding the spot in the firewall to run the power wire through.

Good luck.

1990LS400, you might want to consider researching this topic before jumping all over RDM as he obviously knows what he is talking about with regards to car audio. The picture you posted will NOT do for a 1000 watt car audio setup, there is too much resistance for that much amperage being drawn from for a 1000 watt system. It must be connected directly to the battery. Period. (Not trying to be rude of course) :)

I agree, though I'm betting any amplifier rated at 1000 watts is only putting out half of that. Still, a 4gauge wire would be better suited for the current draw required by such a large amplifier, because you also must factor in voltage drop across the length of the wire too.

Whoa, who actually needs so much power that they need to run 4 gauge wire? You all have a difference of opinion is all. If it was me and it was easier, I'd run it under the car. If it wears out, well so what, run more. I think having all that subwoofer would probably prhobit me from replacing it if it did wear out.

It's not a perfect world but it ain't bad.

Wears out? A wire that size doesn't wear out. I hope not anyway.

[

There is no risk of fire. Use an in-line fuse like my Lexus mechanic did when he ran the power wire underneath my car and put the in-line fuse near the battery or under the engine compartment fuse box for convenience in case it ever blows.

If there are "cracks" to slide wires through to the trunk in a 2000 LS400, I couldn't find them. The gas tank is between the rear seat back and the trunk and there are one or two forgot how many) existing holes plugged with rubber grommets on either side of the gas tank -- the seat back has to removed to access these exiting holes.

You're only half right here. Everyone with a brain knows you would fuse the wire. But if the fuse is at the battery end and your power lead shorts at the other end of the car, what happens? Sure the fuse blows, but only after the ground current travels back to it. If you've ever grounded a wire on accident you know there's a spark. The higher the current, the larger the spark. A wire carrying 50-60amps will make a much larger, hotter spark then if you grounded a 10amp parking light lead. Will that spark ignite anything? Doubtful. But it's still a risk. Fusing it at both ends is safer, but you're still going to have a slight resistance because of the fuse, and it's one more 'serviceable' part you've added.

The bottom line is in the opinion of anyone who does car audio work it's easier to run inside than out. Think about a clean, professional job running a wire under the car, you have to jack it up (jack, ramps, blocks, stands, etc) so that you can access the underside of the car easily. It will be dirty, greasy, and otherwise obscured with debris under the car. You will then need to remove the plastic cover over the fuel lines and secure your wire tightly to them, using zipties every 4"-6" or so to ensure it stays tight and does not gain slack anywhere. You will first of course snake it down from the battery, avoiding the engine, exhaust, and any moving parts, and then snake it up over the rear subframe, again avoiding moving parts and the exhaust. Then you must re enter the car, there are grommets everywhere but you want the grommet sealed to prevent leaks and to keep the wire from moving, chafing, and grounding out. All of this is not hard to do, but you'll get dirtier and spend more time doing it. Running the wire inside requires no zipties, no extra tools, and you can do it in your Sunday best if you really wanted to and not worry about a dry cleaning bill.

But, to each his own. I do find it funny that on this forum when a series of opinions is presented, even with factual data behind them, people get upset and try to argue. No one is saying you (or anyone) has to do anything a specific way, but blindly choosing an option with no basis besides what someone else did is not intelligent. Research the data if you're really that one sided about it, or better yet, since your mind is already made up anyway, don't even bother to post on the subject.

Either way, I'm done with it myself. You guys can continue to bicker but leave me out of it.