Car audio electrical guru's step in


Shawn1112

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So I'm having an issue with my sounds in my 2021 Tahoe. Months ago I put my JL 750/1 amp in on a JL 12W7 sub. Has worked flawlessly for a few months.
Few weeks ago I upgraded to a JL1200/1 with a JL 13.5W7. Used all the same wiring, just transferred it all over to new amp. Running 4 gauge for power and ground as thats what the amp accepts, and running the remote from the fuse box up front. Last week or so the 1200/1 started clipping at high volume. So I just kept the volume down. Son took my truck out the other night and cooked the amp.

So today I throw my 750/1 back in and no power, do all the trouble shooting. Have 14.2 on the power wire coming off the battery, 14.2 in the back as well. The second I connect to the amp, it drops the voltage on power wire and the remote wire to 5.62. So of course the amp wont power up as its not seeing 12 volts. Tried to connect 3 other amps I have and same exact issue with every amp. But the second you pull all the wires out of the amp, I get 14.2 again on both the power and remote. I have never seen anything like that and cant for the life of me figure out why?
 
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Shawn1112

Shawn1112

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Definitely check that ground. Or maybe your subs toast and the amps shorted thru it drawing current
Will check the ground. Sub has nothing to do with the other 4-5 amps not powering up. Sub wasn’t connected to any of those. Also kinda hard to blow a JL 13.5W7. Been scouring around some sounds forums. Some say dont hook up the remote, then see what my volts are reading, others mentioned the ground as well.
 

Turbocharged400sbc

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Voltage drop maybe at the fuse itself I have seen more than a few in line fuses with a massive voltage drop issue inside the fuse plastic block. Most of them are made in China that Ive found.
make sure you buy a genuine busman/name brand fuse

Check the supply voltage with the amp hooked up on both sides of the fuse.

Also be aware that the gold/brass plating on many power distribution blocks does not intrude into the wire cavities as much as you would like and you may find corrosion inside.

Never ground High current amps through the unibody...newer vehicles have so many corrosion Prevention applications to the sheet metal before it is spot welded together that you end up with lots of little areas of voltage drop through the chassis. I don't know how well electrical flow is through some of the new high-strength boron steels...

If I can detect voltage drop on fuel pump wiring which runs at less than 8 amps through a unibody chassis I am pretty sure you're experiencing at least a little at 100amps....
Plus the electron flow is a great accelerator of corrosion I would also try to minimize current flow through my unibody in the Rust Belt with a dedicated heavy gauge ground cable
 

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If you tried three amps and they all do the same then it’s not the amps. What’s your ground look like? Where does you battery ground to? Body or frame of truck? Where are you grabbing the sub signal from? Did you try the auto turn on for the hell of it?

I just went through a ground issues with my car at the headunit. It was introducing static floor noise into my system because my steering wheel control module was not grounded properly. Ground issues suck.
 

Turbocharged400sbc

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Yeah ground Loop noise issues suck the hardest. It kind of sucks because at one point in my Imperial I had the head unit and everything running off the capacitor Bank to get rid of the noise in the lower frequencies as the subwoofer would hit.
 
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Shawn1112

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If you tried three amps and they all do the same then it’s not the amps. What’s your ground look like? Where does you battery ground to? Body or frame of truck? Where are you grabbing the sub signal from? Did you try the auto turn on for the hell of it?

I just went through a ground issues with my car at the headunit. It was introducing static floor noise into my system because my steering wheel control module was not grounded properly. Ground issues suck.
I'm going to go out and do some more trouble shooting today and will start at the ground.
Also as mentioned, everything was working 100% fine up until I made the switch to the 1200/1 amp. Probably has nothing to do with it, but its strange

Brand new truck, so assuming its grounded to the body, arent they all? (not being sarcastic)

Sub signal, meaning my RCA's, if so. I'm grabbing that from the front door speakers using below link

Auto turn on, no. I was always under the impression that only came with some LOC which I'm not using

 

Turbocharged400sbc

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If you have an iffy power feed circuit...crimp, fuse, etc...and ya put in that big bugger in their stressed it enough that something arced sizzled or otherwise and now you actually have hard resistance.

Look for any purpling of the copper strands or any glossiness or any smells
 
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Shawn1112

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Shit just keeps getting stranger by the second.

My ground to the amp is good, could it be better, absolutely but its good enough for now.
When I only connect the power and ground to the amp with the truck running I have 14.0-14.2v at the amp, pre fuse and after fuse at the battery.
The second I throw the remote wire on the amp, it drops down to 5.60ish. So why not jump the remote from the power lead to the remote lead on the amp? Well I do that and the exact same thing happens.

So I grabbed my Banda Viking 8001 amp out of the garage for shits and giggles as I find it hard to believe all 4 of my JL amps are toast lol.
Banda amp has a power light and a low battery/fuse light. That low power/fuse light comes on but not the power light.

I dont understand why I'm having this issue while jumping the remote lead to the power lead. If it was only doing it while connecting the remote lead, then cool, I have an issue with my remote wire.

Edit: Also tried jumping the remote wire with the truck off and same result
 
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Shawn1112

Shawn1112

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Bad ground. You’ve got voltage until the amp starts drawing power. Resistance is going to drop the voltage.
Okey dokey, will give it a shot.
I will just run a new ground. Any thought on how the ground went bad after working all this time?
 
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Shawn1112

Shawn1112

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Grounds are weird.

where or whatis the amp currently grounded to? I swear to god if it’s a seat bolt on gonna hurt you. Lol
Grounded to the body with a self tapper, but all paint was grinded away so its bare metal
 

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