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Sub Amp Cutting Out


Well-Known Member
May 30, 2006
Reaction score
City, State
Boston, MA
Year, Model & Trim Level
'00 Limited
I have the following setup in my explorer:

Kenwood DDX6019 (In dash DVD touchscreen)
Kenwood KCA-BT100 (Bluetooth phone connection)
Kenwood LZH-70W (7" Overhead screen for rear passengers)
Kenwood KFC-ST30 (1" Dome Tweeters / 40w RMS & 120w Peak)
Kenwood KFC-1651S (6.5" Door speakers / 35w RMS & 160 Peak) 2 pair
Kenwood KAC-9102D (Mono amp / 500w RMS & 1700 Peak)
Kenwood KAC-8403 (4 channel amp / 60w RMS & 800 Peak)
Kenwood KFC-W3011 (12" Subs / 400w RMS & 1200 Peak) 1 pair

8ga power wire running from battery (with 100amp fuse) back to a distributor block with a pair of 100amp fuses.

8ga power wire running from the distributor block to each of the amps.

8ga ground wire from each amp to a bolt that secures the rear seats to the frame

the amps are mounted to the back of the plate that is on the back of the rear seats so they are hidden from view. There is ample space for the amps to breathe back there and they don't get bumped into or anything either.

ok now here is the story....

I have the 6.5" speakers and the tweeters running off the 4 channel amp and it runs perfectly fine and never cuts out on me.

I have the pair of subs running off the mono amp (not bridged) and for some reason the mono amp will cut out for like 2 minutes then come back if I am playing the system with the volume up a bit.

I pretty much have the gain set all the way up on the amp but have the bass at -18 on the deck which produces a respectable amount of bass without overextending the subs or the amp.

What am I doing wrong that is causing the mono amp to cut out periodically?

I am considering getting a capacitor for the system but my headlights don't dim with the system on cuz I have HIDs so they take a lower draw from the battery to begin with.


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Do a simple check.

I have had problems with amps doing that as well, most of the time you can track it down to a fuse having a little bit of corrosion on it. Check all of you fuses and make sure they all look good. If the problem continues to occur, I have a Hifonics Zeus Amp that did the same thing, where if you played it low it would not come on but it you cranked it up a bit it would turn back on. This problem occurs when you power supply goes bad and it take more voltage from your head unit (remote wire) to get the power supply to turn on. Check the fuses first, but it is possible that the power supply is going and the amp either needs to be fixed or replaced.

thanks for the input...

I forgot to mention that everything I listed is brand new and less than a month old!

Upgrade your power and ground wire. Pull the speaker wire off the amp and measure the speaker impendance with a DMM. Are the subs dual voice coil? The gain should not be over 3/4.

You should follow TerryS1980's advice and upgrade to the recommended (according to Crutchfield) 4 gauge wiring...

the only reason i have had this happen would be overheating, but you say that they have lots of breathing room. ever gone back and felt the amp, just to make sure?

I used to have this problem and as soon as I upgraded the earth lead it stopped, also try to keep the earth lead as short as possible


ok so I should upgrade ground and power to 4ga wire and double check the breathing room on the mono amp to make sure its not overheating...

Thanks for the advice guys!

I did notice that the 4 channel amp has a small fan on the top of it next to the control panel and is hidden under the cover. The mono amp however doesn't seem to have the same feature unfortunately. Maybe I need to relocate it to a cooler place like behind the panel where the factory sub used to be... I could put the amp and a capacitor in that location and keep the amp for the door speakers and tweters where it is now behind the seat.

I also will turn down the gain to 3/4 as suggested and see if that helps as well

Again, thanks everybody for the advice

You could leave the existing 8 gauge in there for the 4 channel amp.

I have had issues with my Bronco and my Explorer

I have upgraded from the round glass type fuses to the newer blade style fuse holders, this helped because the glass ones would develop a loose fit over time and corrossion would follow.

The ground location on these trucks is very critical, the bolt you are using is okay but you can do better, but here's the trick:


the factory ground cable to the frame and body are smallish and your amp (especially when mounted in the rear of the truck) will have trouble sucking enough ground from the body without upgrading the factory wiring on the other end.....

Both my trucks are old, so the factory ground leads and battery terminal were toast anyway.

No more circuit protection kicking in for me.

This also assumes the rest of your wiring and equipment it up to par, keeping the amp cool is of course also important

I'm using a 6" ground wire that is 8ga going from each amp to the body of the vehicle under the carpet under the rear bench. I am not using the ground from the battery up front. power runs from battery up front to the amps in the abck and the ground is in the back and less than a foot long from each amp.

If I'm going to upgrade the wiring then I will go 4ga all the way around or just do 0ga and know I can't get anything bigger than that anyway.

I'll look into it this weekend and see what I come up with.

You missed my point

the ground wire from the battery to the body under the hood from the factory is not made to take this load.

This is the wire you need to update and upgrade, not your amp grounds the factory battery to body ground

I upgraded the pwer wire this weekend from 8ga to 4ga and relocated the amp from behind the reaer seat to on top of the sub enclosure. I have an 8ga ground wire but am going to upgrade that this afternoon when I get off work.

Amp still gets extremely warm when running high volume and cuts out for roughly 30 seconds at a time

I decided to upgrade the ground wire this afternoon to 4ga and in a week or so I will be switching my amp for a higher end model with more wattage and multiple fans on top for cooling. Hopefully the swap will eliminate the problem

You amp seems to be going in to "protection mode" This is usually cased by overdriving the amp. Being that your sub impedance should not be to low. I was say check to see if 1 of you subs has a bad voice coil. And please, please, please turn down your gain. It should never be even 3/4 the way up. The best was to turn your gain is set you HU to flat (bass to 0). Turn the gain all the way down. Then turn the volume up to your nomall listening level. Next start to increazse the gain until you speaker start to distort. And then turn it down a little. The gain is used to mach the output of the HU to the amp.