Possible audio/engine problem

Chronos[AsG] · Jan 1, 2004

Frist, let me quote another post I made in Sound & Shine:

Hi. I have a 1994 Mustang GT. It came with the Mach 460 stereo system. I have replaced the head unit and used wiring harnesses provided by Crutchfield to wire in the power and amplifier connections. Every once in a while I will get what seems to be alternator noise in the system. I know its not the new head unit as it used to do this with the old factory head unit, which I had to replace because the volume buttons stopped working. It does not hum all the time. Sometimes it will not hum at all, most times it will start as I am driving. I have noticed that alot of times it will start humming when I am on the brake, either stopped or coming to a stop. Turning the radio on and off usually corrects the problem, at least temporarily. Also I'm not sure whether car temperature plays a role. I know it will hum when the car is warm, not sure if it would happen when the car has just been started. I have checked the connectors and they seem to be ok. I've tried checking the grounds but the only ones I could find were the two near the battery and one on the other side of the front engine bay. I know there is one near the inside instrument panel fuse box but I haven't been able to locate it yet, so I dont know if thats my problem. If anybody knows anything that would help, or a way to correct it please let me know. If you have questions or need more info let me know and I'll reply as soon as possible. Thanks!

I have noticed two things since I posted this: First, 99% of the time it begins to hum when I press on the brake. Second, it does not matter if the car/engine is hot or cold.

Early this morning I was leaving a friend's house and I started the car to let it warm up. As it idled (in Park) I noticed a high pitched whirr. This is nothing new, I believe I have heard this before. But I noticed that if I pressed on the brake the whirr dropped in pitch.

This caused me to wonder if this whirr was my alternator, and if I possibly have a bad alternator and this is what is causing this problem with my stereo system. I believe the alternator is the stock unit that came with the car in 1994. So does anyone know if this is what could be causing my problem?

Some other minor points:

Since that first quoted post I have grounded all my stereo components to the same piece of metal in the dash. One ground is a few inches away from the others but I dont think it would be enough to cause a ground loop.

Second, I have ordered a new (well, used) front amp off of eBay in case that's what is causing the problem. The two rear amps were replaced last year.

There are only two other things which I can think of that could be causing the radio noise, though I dont know how likely either are.

First, I have noticed that the AM/FM antenna wire runs pretty close to the stereo grounds and the amplifier near the head unit.

Second, I have different brands of brake pads on the front and rear brakes. The front are stock and the rear are some aftermarket brand. I don't see how this could be affecting anything but I think I have read something about the car being grounded through the brakes and tires.

If anyone has ANY idea what I can do to fix this please let me know. This thing is driving me crazy!

cjones · Jan 2, 2004

since it does it when the engine is also cold. remove the belt and run the engine at idle. if it does it then the alt is not at fault.

ford had a TSB (TSB 01-7-3)for radio whine/buzzing from the fuel pump.

Ethereal Zer0 · Jan 2, 2004

cjones said:
since it does it when the engine is also cold. remove the belt and run the engine at idle. if it does it then the alt is not at fault.

ford had a TSB (TSB 01-7-3)for radio whine/buzzing from the fuel pump.

Any idea if the whine/buzzing stops if you replace the fuel pump?

Gone2 · Apr 7, 2004

I've got almost the same thing. Even with the key to acc. when I first press the pwr button the rear speakers hum. It slowly disappears, but will do it again if I turn the radio off then on again.

If the car is running for a while it will do it constantly. The sound changes with the use of electrical things in the car.

????

mustanggt94 · Apr 7, 2004

Check out my post from a while back...i had the same problem for a year and a half and finally figured it out!

http://forums.stangnet.com/showthread.php?t=387217

bjl95mustang · Apr 7, 2004

When you isntalled you radio did you put an in line converter to turn down the power going to the mach 460 amps?

This is what I did after i installed my hu 4 years ago and I havent had any problems.

The install was easy. First you need to go to Best Buy install bay and get a wiring harness (About $10-15) for a MACH-460 and the inline converter ($35-50 I cant remember the price) this will allow you to turn the output power from the head unit down so it wont hurt the amps. Then go to www.flemworld.com and get the wiring diagram it is under 95 mustang. Once you get all of this stuff you will be set. To hookup the speakers there are the 1or2 (I cant remember) square connectors they are the feeds to the amps this is where you will put the inline converter. Then there is a long connector this is the power and amp turn on (don't forget this one) and stuff like that. To set the converter out put turn it all the way down and turn the stereo 3/4 up then turn the 4 knobs evenly all the way until it starts to distort.

AznStanger3v · Apr 8, 2004

interesting. another one of fords shortcuts: crappy wiring

SuperDust22 · Apr 8, 2004

That's funny I have had this problem forever. I need to read that thread.

Gone2 · Apr 8, 2004

It WAS the connection behind the drivers kick panel. I'm not sure which one exactly because I had "fixed" it before I took the panel off. I think it was the one with the very large grey wire that was almost on the floor board.

DFG 5OH · Sep 8, 2004

Mach 460 Wiring Diagram

I really need a wiring diagram for a 94 Mach 460. I have engine noise in my speakers, and its driving me crazy. I dont know what the problem is, but i hate not having any music.

viperos · Sep 8, 2004

re check all of your grounds... and then the alternator... that's my guess.

DFG 5OH · Sep 12, 2004

I had noise in my Mach 460 also, but i fixed it a few days go. Behind the drivers side kick panel, where the hood pull is, there is a sandwich plug. That plug had come loose, and had come corrosion inside the connectors, so i cleaned the connectors, and put it back together. i wrapped it in metal duct tape, and reattached it to where it went, i also cleaned up the ground behind there, and that fixed my problem.

-Matt

5.0 from 95 · Sep 12, 2004

Most all problems with whine are from grounds. One other thing to check is the cables running through the underside of the dash and when you brake the car it rubs the cables. The connector you put in, did it have a place to ground it? If you grounded it, take it loose and see if it still whines. If you didn't ground it, try grounding it. Some adapters work better with them not being grounded.

Paul

raginbul469 · Sep 12, 2004

another thing u can check is if there is nooise when the car is running u can havea weak cell in the battery or a bad sparkplug wire.

Possible audio/engine problem

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