Power from rear fuse box?

bugeyed

Original poster
Member
Dec 25, 2011
78
I am installing a small amp (175W RMS) for a single 10" sub. Was wondering if the rear fuse box 12v would be OK. I would like to run a dedicated 4 Gauge wire to the battery, but this would get me going until I find & order those parts. BTW I am finding quite a few brand named kits on Amazon, don't actually have the gauge wire that is advertised! For example the Pyle 4 gauge kits have 8 gauge wire. The outside insulation is 4 gauge! That's why I need more time to source the parts.

Thanks,
kev
 

Blckshdw

Moderator
Nov 20, 2011
10,682
Tampa Bay Area, FL
You'll be fine with that. I've been running my 200W RMS amp from there for the past 3 years with no problems.
 

Mark20

Member
Dec 6, 2011
1,630
The power feed to the rear fuse box is something like 0 gauge and fused at 125 amps. You can tap from that.
 

Boricua SS

Member
Nov 20, 2011
3,080
Ohio
:iagree: with everyone... something that low in power, will be just fine...
 

Mark20

Member
Dec 6, 2011
1,630
I have my VHF/UHF mobil amateur radio there and it gets power straight from the battery through that line. The control head is up front. I'll get a picture up one of these days but that's a different topic...
 

STLtrailbSS

Member
Dec 4, 2011
1,617
I ran 750rms in my old tb off that box for about 3 months, still bumped hard
 

DDonnie

Member
Mar 26, 2012
2,631
Anybody want to offer up some pictures of this? I'm just wondering how you are tapping into it. (my apologies if it is obvious, i just bought my TB 3 days ago and havent really looked at everything in detail)
 

Blckshdw

Moderator
Nov 20, 2011
10,682
Tampa Bay Area, FL
dcmtnbkr said:
Anybody want to offer up some pictures of this? I'm just wondering how you are tapping into it. (my apologies if it is obvious, i just bought my TB 3 days ago and havent really looked at everything in detail)

There's a threaded stud with a nut on it. Put a ring terminal (I forget the size) on the wire of your device of choice, and the rest should be self explanatory :thumbsup:
 

Mark20

Member
Dec 6, 2011
1,630
A red HEAVY gauge line comes in to the rear fuse box from the engine compartment (125 amps). You can put tap there. Here's a picture.
View attachment 19880

And a little tighter on the power post.
View attachment 19879
 

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DDonnie

Member
Mar 26, 2012
2,631
Sweet! Thanks for the picture. I have an old sub that I wasnt going to bother hooking up because I didnt want to run power. I think i will be hooking it up now.
 

DDonnie

Member
Mar 26, 2012
2,631
dcmtnbkr said:
Sweet! Thanks for the picture. I have an old sub that I wasnt going to bother hooking up because I didnt want to run power. I think i will be hooking it up now.

Now that I think about it, I'm going to be running something with a bit more oomph than the op. What i have is 1 MTX thunder 6500d amp and 2 MTX thunder 6000 12's. Should this still be safe or do I need a dedicated power source? Are you doing inline fuses after the tap or relying on the 125 amp fuse already in place? Also, I have an ext and was wondering if it would be safe to put the amp in the storage area under the false floor in the back (wife wants it to be simple to take out)? And one more question, will grounding to the frame of the rear seats be safe (between the bolt and the floor) or is there a better place to run ground on these? Thanks for all the help!
 

Blckshdw

Moderator
Nov 20, 2011
10,682
Tampa Bay Area, FL
dcmtnbkr said:
Now that I think about it, I'm going to be running something with a bit more oomph than the op. What i have is 1 MTX thunder 6500d amp and 2 MTX thunder 6000 12's. Should this still be safe or do I need a dedicated power source? Are you doing inline fuses after the tap or relying on the 125 amp fuse already in place? Also, I have an ext and was wondering if it would be safe to put the amp in the storage area under the false floor in the back (wife wants it to be simple to take out)? And one more question, will grounding to the frame of the rear seats be safe (between the bolt and the floor) or is there a better place to run ground on these? Thanks for all the help!

Inline fuse is a must. How do you plan to have your subs wired? 4 ohms or 2? If you're going with the 250W output you'll be fine, if you're going 500, probably a better idea to run power from the battery up front. Here's where I put the amp in my EXT, no need to remove it, just ran the speaker wires under the panel. Disconnect the wires from the box if I need to take it out. Plus I can use a factory ground for a good connection. :thumbsup:

04WiredUp.jpg
 

DDonnie

Member
Mar 26, 2012
2,631
Blckshdw said:
Inline fuse is a must. How do you plan to have your subs wired? 4 ohms or 2? If you're going with the 250W output you'll be fine, if you're going 500, probably a better idea to run power from the battery up front. Here's where I put the amp in my EXT, no need to remove it, just ran the speaker wires under the panel. Disconnect the wires from the box if I need to take it out. Plus I can use a factory ground for a good connection. :thumbsup:

04WiredUp.jpg

Honestly, I'm up for suggestions on how to wire it, I hadnt decided yet. How would you wire it? (I know it's all preference, but Im just curious)

Do you leave it bare like that or do you put the panel on over it?
 

Mark20

Member
Dec 6, 2011
1,630
For my Ham radio (just beyond the power post) there is a fuse in its power lead. That came standard with the design. I'd rather have a short in the radio blow a 7 amp fuse than find out that it isn't pulling enough to pop 125 amps bit still enough to toast the Voy.
 

DDonnie

Member
Mar 26, 2012
2,631
Mark20 said:
For my Ham radio (just beyond the power post) there is a fuse in its power lead. That came standard with the design. I'd rather have a short in the radio blow a 7 amp fuse than find out that it isn't pulling enough to pop 125 amps bit still enough to toast the Voy.

Ha, yea, it was a stupid question on my part. *herp*
 

Blckshdw

Moderator
Nov 20, 2011
10,682
Tampa Bay Area, FL
dcmtnbkr said:
Do you leave it bare like that or do you put the panel on over it?

Where I mounted the amp, is normally where the factory jack goes for the LWB trucks. I removed the mounting hardware for it, and put the jack, pry bar, and wheel chucks in the storage section in the floor that you were referring to. So the panel goes back in place, it's out of sight, and out of the way when I need to (re)move my subs to put larger stuff back there.
 

DDonnie

Member
Mar 26, 2012
2,631
Blckshdw said:
Where I mounted the amp, is normally where the factory jack goes for the LWB trucks. I removed the mounting hardware for it, and put the jack, pry bar, and wheel chucks in the storage section in the floor that you were referring to. So the panel goes back in place, it's out of sight, and out of the way when I need to (re)move my subs to put larger stuff back there.

I like that a lot, is it pretty simple to remove?
 

Blckshdw

Moderator
Nov 20, 2011
10,682
Tampa Bay Area, FL
dcmtnbkr said:
I like that a lot, is it pretty simple to remove?

Yeah, pretty easy. You'll need a T-50 torx bit to remove the bolts for the upper seat belt mounts, then pull the top pieces for the C and D pillar covers. Remove the visible philips screws on the panel and yank, it's held on by clips around the edges. Here's a pic with the jack gear still installed.

01JackInstalled.jpg
 

Mark20

Member
Dec 6, 2011
1,630
dcmtnbkr said:
Ha, yea, it was a stupid question on my part. *herp*

Not a stupid question. I've seen only a couple of amps of current start smoking something. I'll start another thread about that.
 

hitman

Member
Jan 25, 2012
119
Im still on the fence about amping my speakers but when/if i do im going to run the amp off that source
 

ICEJACKEL

Member
Jul 3, 2013
2
Mark20 said:
A red HEAVY gauge line comes in to the rear fuse box from the engine compartment (125 amps). You can put tap there. Here's a picture.
View attachment 5390

And a little tighter on the power post.
View attachment 5389


I tried that and my 07 Trailblazer would not start but all the electrical would come on. I did cut my ring clamp, could that be why? My amp is a 250 watt amp and it's 8guage wire.... any help would be great. My Trailblazer's battery died after I installed a new head unit and amp...and the ground is on one of the baby seat bolts under the rear seat....
 

DDonnie

Member
Mar 26, 2012
2,631
ICEJACKEL said:
I tried that and my 07 Trailblazer would not start but all the electrical would come on. I did cut my ring clamp, could that be why? My amp is a 250 watt amp and it's 8guage wire.... any help would be great. My Trailblazer's battery died after I installed a new head unit and amp...and the ground is on one of the baby seat bolts under the rear seat....

We need pictures of exactly what you cut and where you cut it. Also, did you use a wiring harness that integrated the factory chimes? Also, are you using the stereo remote to turn on the amp? Too many variables, not enough info :biggrin:

Tapping this terminal, on its own, should not be causing a battery drain or a no crank (although the battery drain could be cause by a bad amp)
 

Darkrider_LS

Member
Jan 25, 2013
9,332
Def some good info in here! Reading through this gave me pretty much all i needed to know if i ever wanted to add some thump to my TB.
 

ICEJACKEL

Member
Jul 3, 2013
2
DDonnie said:
We need pictures of exactly what you cut and where you cut it. Also, did you use a wiring harness that integrated the factory chimes? Also, are you using the stereo remote to turn on the amp? Too many variables, not enough info :biggrin:

Tapping this terminal, on its own, should not be causing a battery drain or a no crank (although the battery drain could be cause by a bad amp)


I'm not sure what happened but I connected again and it turned over but now I have to see if my battery is still being drained and if it is from where...I'll keep you up to date..
 

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