I just bought a new 1997 4runner with an aftermarket stereo system. It is just a head unit, with an amp, and the amp powers all the speakers. No sub.

Anyways, I thought I was having a battery drain problem, and when i tested amps with the key off, I was only getting .1 amp drawn. Which I think is normal, correct? (I have an aftermarket alarm).

While I was testing it, the pos (+) wire that goes TO the amp, touched the neg (-) terminal on the battery and sparked. This is with the pos (+) wiring harness completely disconnected from the battery.... and the amp was not getting any voltage, yet when testing with a volt meter it had 10V!!! (The 4 ga wire that just powers the amp) What the hell!?? Its like the amp was acting as a voltage source!?

Also how long can you listen to an amplified stereo system without it draining the battery low enough that you cant start? I listened to about 5 minutes of songs sitting one day w/o the engine on, and it BARELY started. I'm thinking the battery is bad.

Lastly, sometimes I get static on the speakers. But others not. Sounds like interference. I can't replicate it, and it seems sporadic. What do I check?

 

I am little confused on this. You unhooked the 4ga wire from the battery, it touched the (-) terminal on the battery and it sparked? Are you sure there is not a capacitor?

It sounds like the battery is on its last leg and will need a replacement soon.


The first place to check is the ground. A poor ground on the amp can lead to static. Make sure it is secured tightly and that there is no corrosion, paint, or other inhibitors between the ground and the connector.

Also check to ensure that the RCAs are securely pluged into both the radio and the amp.

The most common cause of static, but also the biggest PIA to check is low quality RCAs. Most times that you hear static, it is "Engine Noise" and comes from poorly shielded RCAs that are run too close to other high current wires. the easiest way to check them is to run the directly from the radio to the amp right down the middle of the truck. (Just flopped in there) That way there is no way they are near any outside influences.

You could be getting noise from the speaker wires themselves but that is much less likely.

I hope this helps narrow down the problem.

 

There is a tenth of an amp draining? That seems like a big draw to me. I don't know what it should be for your rig, but the cars I work on all day (Chevy's) the normal draw is 6 milli amps.

 

i agree with VA07.

what exactly do you have for a system? your whole set up. and ground ground ground. get that sucker to bare metal. and change that battery. its junk. what date was it installed? you could always do a load test for free at a local parts store just to double check. but yeah that battery sounds like its done. which will put strain on your alternator trying to keep up with a system.

and if you have a capacitor junk that too. some guys believe in it some guys don't i think its a band-aid.

 

Thanks guys, never been a stereo guy, so I'm learning as I go. I do understand basic circuits and electrical stuff though.

Yes, I unhooked the 4 ga wire that runs from the pos (+) to my amp (The wire that I thought powers my amp), it sparked when I hit the negative terminal. I read a voltage difference of 10V between that wire and the negative terminal. I traced this wire, and did not see any capacitors inline. Do they reside within the amp? It must have capacitors if its holding a voltage!!?

Yes, I also believe the battery is crap/gone. I can't get a date reading off of it. I can't find it at least....

Also the .1 amp drain... I tested again, and it is .1 amp for about 1 minute, and then it goes to about 5 mA. I read up that some cars require a time delay before they go into a "sleep mode" in which they draw less amps.

I will check grounds and RCA cables as well.

I am a little concerned about how the amp is wired. It appears to be just a 2 channel amp, yet, it powers both front/rear speakers and tweeters..... Is that normal?

 

Also, I can't get my antenna to work.

I know the blue wire from the head unit is power antenna power, but what do I connect it to on the Toyota side? :/

 

I would trace that wire hand over hand to ensure that it is leading to where you think it is leading and that nothing else is tied into it. Something is definitely not adding up. A capacitor is not something that you would easily overlook as long as it isn't hidden under a seat, behind a kick panel, or something of the like. Capacitors for car stereos are not something that is small like a capacitor in normal home electronics. They resemble beer can on steroids. One wire in to positive, one wire out from positive, and one wire to ground, for a total of 3 wires. (Generally. I have seen some Jerry rigged stuff with multiple wires.)

Another option is to unhook the wire on both ends (amp and battery) and take a simple resistance test to make sure there is continuity between both ends.


There is nothing wrong with running 4 speakers off of a 2 channel amp as long as the amp is stable at the ohm range in which the speakers are designed. *Assuming it is wired correctly* You are running 2 speakers off of each channel. With running 2 speakers off of each channel you have doubled the resistance that this channel sees. Assuming you are running the conventional 4ohm speakers, you now have 2ohms of resistance. Most 2 channel amps are fine running at 2 ohms but it would still be worthwhile to search the model number of your amp to ensure that this is the case with your particular amp.

The Downfall to running 4 components off of a 2 channel amp is that you will lose either balance or fade due to the fact that you can only control 2 channels. It can be set up as left-right or as front-back. A 4 channel amp gives you ability to still maintain factory style settings concerning the balance and fade by having the ability to control each of the speakers individually. Another downfall is that it causes higher loads on the amp due to the higher resistance thus causing the amp to "work harder". On low quality amps this will become an issue and may cause them to go into "protect mode" due to too much heat. It can also cause the amp to fail prematurely due to the higher heat. This is just like any other electronic device....they don't like heat. The cooler they are the more efficient the run and thus, they generally last longer.

Another way to test if it the amp causing the signal noise or if it is something that is coming from the head unit or RCAs is to unplug the RCAs all together from the amp but leave the amp on. Unplugging the RCAs ensures that there is no signal coming into the amplifier. Drive around and do whatever you normally do to try and replicate the problem. If you hear static in the speakers then you know it is either the amp itself or the speaker wires. If there is no static or signal noise then you know the amp and the speaker wires are fine and the problem is coming from the RCAs or the head unit.

The next step would be to plug the RCAs back into the amp and unplug them from the head unit. Repeat the same test as before and listen for noise. If no noise is heard, the speaker wires, amp and RCAs are fine and the problem is in the head unit itself. If noise i heard in this step, it is the RCAs.

 

Wow! Thanks for your awesome response!

Ok I will check continuity of the 4ga wire running from the positive terminal to the 12V on my amp.

The amp itself seems very powerful, as the speakers seem they can blow my windows out. So hopefully the guy sorta knew what he was doing when he bought the amp and wired all the speakers to it.

I unplugged the RCA cables going to the amp, and there is still static. I just put in a new head unit yesterday, only because the old one didn't have an aux input. Both HU's had the static.

So the static is coming from the speaker wires. I can put the HU on to "aux" and put the volume all the way down, and the static is still there. I double checked the ground, and cleaned off to make sure it was hitting bare metal. All speakers are making the static noise, albeit quiet, its still noticible.

I then re-connected every connection on the amp, and still there. The 12V 4ga wire does run near the speaker wires for about 8". I tried moving that around and it still caused problems. Maybe i should try another amp.

 

No problem.

If you still have static when the RCAs are unplugged from the amp, it means that the head unit and the RCAs should be good to go.


It doesn't always mean that it is the speaker wires causing the problem. The problem could still be the amp itself. To me it sounds like the problem is going to be the amp itself due to all of the speakers having the static and it not being an issue of the RCAs. Generally speaking if the speaker wire was an issue, you would only be getting static though the speakers in which had wire running near or across other high current wires.


If you have access to another amp, it would be a good idea to throw it in there and see if the results are the same. Like I just said above, I think you are going to find that something has gone wacky with the amp.