Question about Kenwood KAC-728S Car Audio Amplifier

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No power turn on??

The positive from the battery is 12v the remote wire form my deck is reading 12v. now when i connect the pos and grd, it still reads 12v, as soon as i connect the remote it reads 8.5v from the pos and the remote to grd. and no power on to the amp. I just dont understand. Please help!

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Re: No power turn on??

Does the voltage at the battery drop when you connect 12v to the remote terminal?

If not, there is too much resistance in the power/ground wiring.

If the voltage drops at the battery, either the battery is weak or the amp is drawing excessive current.

Posted on Dec 03, 2007

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Do i havde to have thed module hookec up in order for the amp to turn on?

u have to have the positive wire running from battery to amp and the neg off the amp grounded to metal in the trunk then u most have the remote wire running from the back off the deck to the amp if it does not power the amp and u ran the (+) (-) the right way then that means u did not connect the remote wire which is blue to the right wire in the back of the deck when u do that the amp will turn on. the remote wire is for when u turn ur car off the radio shuts off with it but it has to be connected to the right wire on the back of the deck in order for the AMP to power up.

May 18, 2011 | Kicker ZR600 Car Audio Amplifier

1 Answer


Most amps have a remote on terminal, which takes a small current wire to "turn on" the amp, and when you stop current to that terminal, it turns off the amp. It sounds like this current is still live when you turn the car off, so your amp doesn't know to turn off.

With the car off, test the lead at the remote on terminal (usually blue wire, as I do it) with a dc meter or test probe. If it reads +12v, it shouldn't. Find a new "remote on" power lead. This is generally provided by the "power antenna on" lead out of the deck. Run a wire to the amp from the power antenna on lead, and retest.

I'll bet on success after this.


May 05, 2011 | Rockford Fosgate Punch 200a4 Car Audio...

2 Answers

Amp wont turn on and theres power to the amp and the fuses are good

check the ground to the amp. then check the remote wire. make sure u have the sub option on ur stereo turned on. if all is wired up correct an u do not have the subs turned on in ur stereo settings then the stereo will not send power through the remote wire an therfore your amp will not power on.

Apr 04, 2010 | Rockford Fosgate Power T3002 Car Audio...

1 Answer

Doesnt turn on

Three things to check.

Are all connections secure? Check and double check this.
Is there 12V coming to the 'remote lead?' Use a 12V meter from your local Walmart to test when the deck is turned on there is power going to this lead. No power and the amp will not turn on.

If there an inline fuse on the Power or Battery + that has blown? If so check and change this.

Jul 07, 2009 | Legacy Audio LA420 Car Audio Amplifier

2 Answers

I got a stock ford JBL amp with no wiring diagram i need to know what wires are what i have tryed to test for the power wirer but no luck.

ok on most amps there are two sets of wire ports one for speakers & one for +12v,grd & 12v remote start if you look over each port it will say what port is for what wire if it is in a connector it gets slightly more complecated what you do is with a vm check from wire to chassis ground [like seat bolts] 12v with key off when you cet power isolate wire then turn key on till radio comes on then do the same test for 12v isolate that will be remote start then turn key off &check from the first wire to other wire for ground to find speaker wires connect a regular peace of wire to chassis grd & touch the wires you will here the speaker pop be sure not to hold the wire on long cause it will blow the speaker

Jun 04, 2009 | JBL BP1200.1 Car Audio Amplifier

1 Answer

Infinity Reference Amps stay illuminated

Hello shaymus_hoos,

No, it isn't supposed to work that way. Although amps are usually wired with the positive directly to the vehicle battery, they aren't supposed to turn on unless power is supplied on the remote wire.

The problem is most likely in either the head unit or one of the amps. And if not corrected, the amps will sooner or later, completely drain the battery.

First see if it works properly with just one amp connected. Remove the remote turn-on from 1 amp at a time and test with the vehicle and head unit off and then on. If the problem is still there with just one amp connected, either the head unit is at fault or the remote wire is picking up 12V somewhere along it's path to the amps. Make sure you have it connected to the right wire on the Kenwood. Every Kenwood I've seen uses blue/white for the remote wire.

If both amps work OK separately, one of the amps is causing the problem. You may be able to correct it by using a relay to electrically separate the turn-on signal for each amp. You'll need a "double-throw, single-throw" type of relay. Here's a link to the Basic Car Audio Electronics web site that details the connections Connect the remote wire coming from the head unit to one side of the relay coil and ground the other side. Bring 12V positive from an "accessory" lead that is hot only when the ignition is in either the "ON" or "ACCESSORY" positions to one side of both sets of relay contacts (it doesn't matter which side). Connect the other sides of the relay contacts, one to each amp turn-on connector.

Hope this helps.

Apr 22, 2009 | Infinity Reference 7541a Car Audio...

1 Answer

Green light, No Power

Disconnect the remote wire and make a jumper at the amp from the 12v + to the remote input and see if you get the same results. If yes, then you probably have a bad ground point. It might not be able to handle the transfer load it's receiveing. If no, then you have an issue with your remote wire or power wire. Check for any kinks or pinches in the wire.

Jan 25, 2009 | Sony Xplod XM-1652Z Car Audio Amplifier

2 Answers

Quick question about the power

The remote turn on terminal on the amp needs to be connected to a switched power source. Typically, it's the remote turn-on/power antenna wire on the head unit. If your head unit doesn't have such a control wire, connect the remote turn-on terminal to a wire that's controlled by the ignition switch.

It's VERY important to fuse all of the wires properly. If you're unsure of the proper fuse for a given wire size, read pages 14 and 16 of the Basic Car Audio Electronics site.

Let me know if you have any other questions.

Oct 21, 2008 | Sony Xplod XM-554ZR Car Audio Amplifier

3 Answers


Try removing the remote turn-on wire from the terminal on your amp. If that shuts it off then you can use either the remote turn-on output from your head unit, or any fuse at your fusebox that only comes on with the car on.
If that doesn't shut it off the amp has an internal short and should be replaced or you could put an easily accessible fuse in its power wire and pull that when you wanted to shut it off.

Mar 06, 2008 | Power Acoustik LT-980/2 Car Audio...

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