Does the trailer power tap under the hood power anything else?

[Sqrly]

I'm going to add an audio amp (mine didn't come with one) for a single sub woofer. I plan to install the amp in the stock location and run a new 10ga power line right to the under hood fuse box.

The stud powered by the 30A trailer fuse #32 looks perfect and that's the size of fuse the amp requires. It has one in the amp but I want one at both ends.

I just want to double check with you guys so my question is, does that fuse supply power to anything else? There's nothing hooked to the stud currently.

 

[Mooseman]

Nope. That is the only thing that stud/fuse was for.

 

[Sqrly]

Nope. That is the only thing that stud/fuse was for.

OK, thanks for the confirmation.

 

[budwich]

beware that it is powered all the time...ie. key on or off so hopefully your amp has a "trigger" line.

 

[TequilaWarrior]

If you're using a stock headunit with a converter of any kind, TEST whether the trigger works as expected. I have a PAC kit on mine and my trigger works off the RAP circuit. Any time I unlock the doors, my amp turns on for a short time.

Personally, if I were to run wire to that tap, I'd just connect to the positive connection on the battery. If you don't expect your amp to tax that circuit, it's not a big deal. Mine is fused 50 amps at both ends and I have a stiffening capacitor due to power fluctuations - even with the big 3 upgrade my headlights bounce.

If I recall, the factory amp location is in a hollow space above the rear wheel well, slightly forward of the rear wheel. That's not a very clean place and has poor circulation. But again, depending on the amp, that might not matter. My Kicker would not have liked that spot at all - especially after I added the fan.

 

[Sqrly]

beware that it is powered all the time...ie. key on or off so hopefully your amp has a "trigger" line.

Yes it does. That will connect to the corresponding output from the aftermarket stereo itself.

The stereo also has seperate RCA Sub-Woofer outputs and I am adding a line level volume control that I'm going to mount below the 4WD rotary switch so I can adjust it without looking at the stereo since in only has one knob for volume and everything else is touchscreen. I had to go with touchscreen to have it double as a screen for the backup cam I added.

Add to that I'm getting a "Bazooka". I've had one before. It is held in place by velcro straps so you only have to screw down the small bottom mounts. This makes it easy to quickly remove by hand should I need to fold down the midgate.

 

[Sqrly]

If you're using a stock headunit with a converter of any kind, TEST whether the trigger works as expected. I have a PAC kit on mine and my trigger works off the RAP circuit. Any time I unlock the doors, my amp turns on for a short time.

Personally, if I were to run wire to that tap, I'd just connect to the positive connection on the battery. If you don't expect your amp to tax that circuit, it's not a big deal. Mine is fused 50 amps at both ends and I have a stiffening capacitor due to power fluctuations - even with the big 3 upgrade my headlights bounce.

If I recall, the factory amp location is in a hollow space above the rear wheel well, slightly forward of the rear wheel. That's not a very clean place and has poor circulation. But again, depending on the amp, that might not matter. My Kicker would not have liked that spot at all - especially after I added the fan.

It's an aftermarket because I wanted to add a backup cam, BT, USB, and SDCard. It does have a volume knob though, that is also important to me.

I installed it with the matching PAC kit but I'm going to tie into the trigger right out of the stereo since my vehicle didn't come with the bose system.

You're correct on the location. It doesn't get any airflow but it is a fairly large volume. I pulled that entire side off (interior panels) to run the backup cam wiring. The amp has thermal proection but I'll rarely work it hard. It already had Kickers in the doors and they sound fine fed by the stereo itself. I just want the full range of sound, I'm not one of those that makes noise just so others can hear it.

The amp I am using is ancient and tough as rock. It's from a time that when they said 80W they meant "80 Watts RMS at 4ohms with less then 0.001 harmonic distortion". It's 40x4 or 80x2. I'll be using it bridged to run a single dual voice coil 6" sub.

I found one on Ebay like it. This thing is a beast. I've hooked it up to my Pioneer CS911-A home speakers using a 25A 12v power supply and a PC for input and it puts my home stereo to shame power wise.

Acoustic Research GCS80/40 car amplifier https://www.ebay.co.uk/itm/27669607...=0&customid=link&campid=&toolid=20001&mkevt=1

 

[Sqrly]

Earlier I needed a distraction and read the entire "Misconceptions" thread.

I found in there that this "Trailer" stud is actually for charging an accessory battery. I don't understand why there's nothing hooked to it. I have a 2" reciever with a large pigtail socket next to it in the back. Does it not have a 12V accessory line already in the plug?

 

[Mooseman]

It does but for whatever reason, back then, GM decided to not connect the red wire that powers the trailer plug's aux power, which is usually to charge the trailer's on-board battery, either the emergency brake's or an RV's house battery. Even full size trucks were like that and those they left the electric brake's wire disconnected from a second post. All this is also in owner's manuals.

 

[budwich]

I think they saved the cost of a relay...

 

[Sqrly]

It does but for whatever reason, back then, GM decided to not connect the red wire that powers the trailer plug's aux power, which is usually to charge the trailer's on-board battery, either the emergency brake's or an RV's house battery. Even full size trucks were like that and those they left the electric brake's wire disconnected from a second post. All this is also in owner's manuals.

Now I must go hunt for this red wire. The previous owner towed a 25' foor travel trailer with this vehicle.

The only red wire I've seen, other then the one to the main fuse, is the one across the bottom of the picture and it goes to a ground point on the body just out of the picture on the right. I assume it's large as it hooks to a 30a fuse?


Update: Now that I'm looking for it I think it tried to bite me! That wire is tiny for a 30A circuit intended to run beyond the full length of the vehicle. Theoretically it should be big enough. In the real world, I would not trust it.

 

[TequilaWarrior]

I'm going to add an audio amp (mine didn't come with one) for a single sub woofer. I plan to install the amp in the stock location and run a new 10ga power line right to the under hood fuse box.

The stud powered by the 30A trailer fuse #32 looks perfect and that's the size of fuse the amp requires. It has one in the amp but I want one at both ends.

I just want to double check with you guys so my question is, does that fuse supply power to anything else? There's nothing hooked to the stud currently.

View attachment 114741

It just occurred to me to check a amp/length chart.
At 30 amps, 10GA is good for about 8 feet.
12 feet at 30 amps should be a minimum of 8GA.

My amp run is 4GA and fused 50 Amps at both ends and the amp is fused at 40 amps (30 from the factory but they're known to be stable to 40+). My run is also pretty short... from batt + straight through the driver's firewall, under the seats to the hatch... 12 feet maybe.

If you're going to put 30 amps on that circuit, I'd bump up the gauge on that wiring.

 

[Sqrly]

It just occurred to me to check a amp/length chart.
At 30 amps, 10GA is good for about 8 feet.
12 feet at 30 amps should be a minimum of 8GA.

My amp run is 4GA and fused 50 Amps at both ends and the amp is fused at 40 amps (30 from the factory but they're known to be stable to 40+). My run is also pretty short... from batt + straight through the driver's firewall, under the seats to the hatch... 12 feet maybe.

If you're going to put 30 amps on that circuit, I'd bump up the gauge on that wiring.

Naw, Ohms law. Power = Voltage * Current. So 160 watts RMS at 12V = 13.3 amps.

(In practice the current is even lower because auto systems actually run between 13.7 and 14.7 volts with the engine running and you should see at least 12.2V to 12.6V when the car is turned off.)

All the fuses are fast blow to protect from shorts. High power audio amplifiers can create lots of large current spikes, that's why the fuses are so large. Over twice the maximum 'average' current in this case.

 

[TequilaWarrior]

Naw, Ohms law. Power = Voltage * Current. So 160 watts RMS at 12V = 13.3 amps.

(In practice the current is even lower because auto systems actually run between 13.7 and 14.7 volts with the engine running and you should see at least 12.2V to 12.6V when the car is turned off.)

All the fuses are fast blow to protect from shorts. High power audio amplifiers can create lots of large current spikes, that's why the fuses are so large. Over twice the maximum 'average' current in this case.

While that is probably accurate under expected usage, I'm more concerned about the max draw. The amp itself has a 30 amp fuse in it. You're wiring needs to carry that current if that fuse is to do it's job. Personally, I would not be comfortable counting on wiring that's rated for half that - fast blow or not. But it's your rig and your choice. You're probably right and shouldn't matter.