Ever so often when I start my 94gt there is a very loud roaring noise coming from the speakers. No radio sounds, only the roaring. Previous owner installed an aftermarket radio and the only way I can get the sound to quit is remove the removable face plate. I can reinstall the faceplate at a later date and the radio will be normal. The noise never comes on while I am driving. Only at start up. The noise is so loud that it would be undrivable without taking the faceplate off the radio. I believe it is coming from all the speakers. This happens about once ever 2-3 months, not ever time I drive it. I haven't looked for loose grounds and would like a heads up on where to start. It has the amp thing in the trunk under the rear deck.
Very loud roar coming from the speaker
- Thread starter tinnocker
- Start date
ttocs
Post Whore
is the deck the only thing that was replaced? Exactly what gear is in the car now? Do you have the mach tweeters behind the mirrors? The noise you hear does it go up/down with the engine rpm?
The good news...it has quit roaring. There are two amps(?) mounted under the back deck, one under each speaker. I can't actually see the speakers. They are mounted on the top side under the rear glass, covered up by large speaker covers. I wiggled the wires going to the amps(?). One seemed like it was about to come off and it did slide in about an 1/8" when I pushed on it. The gear doesn't matter....it will roar without the engine running. I did not start the car because it is so loud that I want to cut it off before a speaker is damaged. The car fixed itself since it was sitting flat on my concreted driveway.....no bouncing to shake a loose wire, unless the connection that I talked about was the culprit. I don't know if the amps / speakers at the rear deck are stock or not...they look like they came from the factory. It has the small speakers at the front windows. When it is roaring, it is so loud that I can't tell where the sound is coming from...each speaker I would guess. But as I said it is normal for the time being.
ttocs
Post Whore
ok so it sounds like the radio was replaced and wired into the factory mach system which if everything is done right isn't too bad. The mach amps have been known to be a battery drain if your having battery issues though and they can be easily bypassed if you replaced the speakers and hit the bypass harness behind the radio. I am going to sound crazy saying this but to help us isolate that the problem is next time it happens give the dash a couple of light taps and see if it changes anything. If it doesn't then go back to the trunk and see if jiggling the wires or some technical taps on the enclosure/amps does anything.
My battery does drain and I have to recharge. Could you go more into detail about what to do to the mach amps or the Pioneer radio to stop the drain. I have not replaced the speakers but I don't know what the previous owner did. What is the bypass harness? I can pull the radio but I do not know what to look for or what to do.
ttocs
Post Whore
to fix the battery drain you either need to replace the amps or bypass them and remove them. Inside of the dash right next to the radio is an 8 pin standard for (70-1770 is the model number) harness that goes from that location to each of the tweeters. What you do is wire your radio into that speaker harness, and then replace the speakers and rather than use the speaker wire that goes to the woofer use the speaker wire that goes to the tweeter and you have bypassed the amps. Your going to lose some bass with out the rear amps/woofers but with a good set of coax or comp speakers you will be almost as happy with the sound, but much happier with the lack of the battery drain. If you want the bass back a small sub in the trunk will give more than the factory subs ever did.
Thanks ttocs for that info. When it was making the roaring noise I popped one side of the removable anti-theft cover plate out about 1/8 inch and the noise quit. Did this cut power to the Mach amps? If so I cut just pop it out a little each time I cut it off for extended or overnight times and it would be a simpler fix. This may have just broke the speaker connection and the amps would still be hooked up and still drain the battery. Just asking your opinion.
ttocs
Post Whore
no the mach amps will drain power no matter what you do to the deck
I had time to look into my problem today. Evidently when I said the noise had quit I didn't have the engine running. There is no noise when the switch is on accessory and the radio plays as it should. While the radio was playing I took the heel of my hand and hit on each door speaker and the area around the radio, and on each amp box in the truck. No noise, the radio played as it should, all speakers are working even those above the amps. When I started the engine I get the noise and it changes tone when I rev it up......higher pitch, lower pitch when I let off. I bumped around each speaker and amp and the noise did not flutter, still the same. I did some research and some posts say it may be the alternator. What do you think, ttocs? Would that be what you would check next? The alternator looks to be the original and is charging ok but I read something about a diode. If that could be the problem, is it located outside the alternator of built into it. Would I have to take the alternator off and have it checked at the auto parts store? Thanks for the help.
ttocs
Post Whore
does the noise go up/down in pitch with the rpms? Can you take a pic of the coil under the hood? Attached to it there should be a small(1/2") metal can with a single wire.
Yes, the noise goes up/down with the rpms. I tried to post a picture of the coil but had some problems. It is an Accel coil and I see the can you were talking about. Looks like a condenser from a old point distributor and it has a single wire
ttocs
Post Whore
yes it is a noise condenser and for no less than to help keep the noise the ignition creates from getting into other areas like the audio. They can be a little bit of a challenge to find sometimes with the right harness but I would start there. Next time you have the noise maybe go try jiggling it.
I can find nothing on the noise condenser from forums or supply houses. There are many for earlier 60-70s Mustangs and point distributor cars but when I google one for a 94 Mustang I come up short. Would they all be the same and would a universal one work as long as it had the right terminal. Yesterday I had the noise every time I ran the engine. No music or sound comes out while it is making the noise. The noise is so loud it may be picking up the stations but I can't hear them. The radio plays perfectly with the engine off.
ttocs
Post Whore
the harness connection is the only thing that is different as far as I know but I really think there is a bigger problem somewhere. Alternator noise is can get loud but its normally something that doesn't overpower the music to where you can't hear it at all, and its also not normally something that comes/goes. But with that being said I would try one of the replacements even if it meant installing a new connection/harness to it.
Well, I think I found the problem or the vicinity of the problem. After reading many forum posts about radio noise and Mach 460 noise, I found two that mentioned the noise would flutter while kicking on the driver's kick panel. Mine was roaring 100% of the time while engine was running and I would just pop the removable faceplate off while driving it, so I started it this morning and clicked the faceplate on and the noise started. I kicked the driver's kick panel with the side of my foot and the noise would skip a beat and then quit. I took the kick panel off but could find no naked wires or nicked wires. The radio played normal without the engine running so I started the engine and it still played normal. I wiggled wires and looked closely with a flashlight but could find nothing out of place or no naked or pinched wires. Put it all back together and all is good. Thanks for all the help I got.
ttocs
Post Whore
there is a harness related to the mach system in the kick panel that I thought split part of it out to the door speakers and then the harness continued up to the deck area. If I can remember to get my wire bible I can try and look up what it looks like. There might be a ground that comes off of it and goes to the kick as well that needs attention.
