The infamous capacitor discussion

[LongThrow]

it's an internal part of most stock alternators, it's unlikely that it failed new but its possible and should be checked. the other option would be the computer commanding the alternator to a lower voltage.

Your Explorer's charging system is simple. A computerized charging system tester should make quick work of this, although there's a slight chance a tech may need to take the vehicle for a drive to confirm the problem. Nobody can tell you if an auto shop will charge you for testing it, but I doubt this has anything to do with your sound system's current draw. Expect them to find a problem that will cost you money.

Appreciate the advice. If my charging system checks out fine, and it isnt the PCM controlling the alternator, what else could it be?

One last question - take it to a mechanic shop - auto parts store - or audio installer?

 

[wew lad 5,000+ posts]

reputable mechanic shop that works with alternators often would be ideal.. give them some time to figure it out. that's really the most likely thing it could be besides a bad battery/alternator/pcm or bad grounds.

 

[n2audio 5,000+ posts]

Another vote that the sound system isn't the issue, and that a cap isn't the solution.

This is a long thread, but it may be helpful:

Voltage Issue's! any idea's? - Ford Explorer and Ranger Forums "Serious Explorations"®

I spent about 10 yrs driving fords with 75-130A alts running about 2x the power you're running and never saw any voltage fluctuations like that. A little dimming at high volume was the worst symptom I ever had to deal with. Incidentally - I had the most trouble with the 130A. Blew it 3x (I think, at least 2) in about 3 yrs. The 75A alt ran pretty well but eventually failed at 226k miles.

Also, Alts can be tricky. As you're experiencing - when they act up, they don't always do it constantly, and they don't always do it when they're cold. When my 130A failed on the road I took it off and took it to the store for warranty replacement, but the thing tested fine. I had to get semi-nasty with the store insisting that just because it tests fine for a minute or two in the 70 degree store doesn't mean it works under the hood at ~150 degrees after a 30 mile drive.

 

[los33]

Sounds to me like a very bad ground loop either caused by the amplifier ground or your amp power wiring.

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[AcMekanik]

An explorer of that year wouldn't have its charging system controlled by the PCM, just internal reg on alternator. My 87gt came with an 85 amp alternator which at idle produced maybe 30a. I did the 3g 130 upgrade then when I put on an electric fan and 1K wrms of audio and it performed fine with no dimming. My 03 f150 has the stock 130a alt. and as of now I'm running at the most 1.6K wrms and only have dimming at high volume. I did do a big 4 tho. If you are only running 650 wrms that 95a alt. is prolly your prob. especially if you are at idle running your system. That alt. likely doesn't charge 95a at idle, more like 40-50. Get a 130a, shouldn't be that much. The 130 3g should fit that explorer with minimal mods, if any. Then do big 3.

 

[i2ain2thunder 10+ year member]

I bet they help to float voltage. Plus the big ones, or Multiples run together, //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif why not, **** not like it hurts do it if u want or don't. IDGAF

 

[dev199505]

The issue more than likely is the alternator especially if you bought it from autozone they have a tendency to sell DOA electronic components

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[UMWDawg92 10+ year member]

These older ford alts do not produce much at idle, in my 88 f150 I had the 2g 85amp stock. I put on underdrive pulleys with a large alt pulley that was supposed to maintain stock charging and I could barely run the heat/ac, wipers and headlights at the same time. I would get voltage drop with just that at idle. While above ~1500rpms it was no issue. I had the 5.0 and it idles down around 700rpm. I swapped in a 150amp 3g to prep for my small stereo install and fixed all voltage drop. I also did the big 3 in 1/0 at the same time. I picked up the 150amp 3g for ~$100 online.

 

[dev199505]

These older ford alts do not produce much at idle, in my 88 f150 I had the 2g 85amp stock. I put on underdrive pulleys with a large alt pulley that was supposed to maintain stock charging and I could barely run the heat/ac, wipers and headlights at the same time. I would get voltage drop with just that at idle. While above ~1500rpms it was no issue. I had the 5.0 and it idles down around 700rpm. I swapped in a 150amp 3g to prep for my small stereo install and fixed all voltage drop. I also did the big 3 in 1/0 at the same time. I picked up the 150amp 3g for ~$100 online.

Sorry for the momentary thread jack Do you know if that alt would work in a 2.9l Ford ranger

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[Tripn88]

If it does it when the system off like you said then it isn't the problem.

Sometimes mine will drop to 13 then jump back up when the alt kicks back on. Have the shop check your alt with a load multiple times back to back.

Autozone tried to tell me my starter wasn't bad because when it was cold worked. I asked them to run it back to back and sure as **** 3rd time was the charm. Got hot enough wouldn't engage. Could just be a faulty alt or regulator. Honestly you should be able to start a car and disconnect the battery if it dies the alternator is bad. That's how I've always checked mine. (Certified shade tree mechanic) lol

 

[wew lad 5,000+ posts]

If it does it when the system off like you said then it isn't the problem.
Sometimes mine will drop to 13 then jump back up when the alt kicks back on. Have the shop check your alt with a load multiple times back to back.

Autozone tried to tell me my starter wasn't bad because when it was cold worked. I asked them to run it back to back and sure as **** 3rd time was the charm. Got hot enough wouldn't engage. Could just be a faulty alt or regulator. Honestly you should be able to start a car and disconnect the battery if it dies the alternator is bad. That's how I've always checked mine. (Certified shade tree mechanic) lol

I wouldn't recommend disconnecting the alternator while it's running.. very bad idea. Might work on older vehicles but you risk frying things on newer vehicles

 

[adulbrich 5,000+ posts]

I wouldn't recommend disconnecting the alternator while it's running.. very bad idea. Might work on older vehicles but you risk frying things on newer vehicles

He said disconnect the battery...

That's a common thing to easily test if your alternator is working

 

[wew lad 5,000+ posts]

He said disconnect the battery...
That's a common thing to easily test if your alternator is working

i've read multiple people state that's a bad idea.

 

[adulbrich 5,000+ posts]

i've read multiple people state that's a bad idea.

On newer cars? Maybe.

On a 94 Explorer? I wouldn't worry about it

 

[wew lad 5,000+ posts]

On newer cars? Maybe.
On a 94 Explorer? I wouldn't worry about it

I agree with you, but I want to make sure someone else reading this doesn't think they can do this on any vehicle. Similar to how caps can help, but it's still a no no to advise someone to use a cap to help with voltage drop