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Discussion Starter · #1 ·
So installed new speakers in a 1999 mustang. Passenger side both front and rear speakers are not producing bass.

driver side (both) are doing it just fine. When I connect the speaker wire from the driver side speakers to the ones on the passenger side they produce bass so its not a speaker issue (speakers are brand new and work perfect when ran from driver side wires).

What could it be??
a ground issue??? wiring behind the stock stereo/cd player??

any ideas would be great.
 

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Sounds like a problem in the head unit. If you're getting bass in 1/2 the car but not the other half, then it's the head unit that's at fault. :duh:

Unless you have a wiring diagram (unlikely and probably not worth it) and are willing to dig into it, I'd junk it and install a new one.

If you're not willing to do that, then try running mono instead of stereo and wire both sides to the left side.

Perhaps junk the whole Mustang and get a MKII. :thumbsup:

Whatever you decide, good luck.
 

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Maybe try a resistance check on the wire from the head unit back. Pinched somewhere or corrosion?


edit....
In case this helps, a wirng chart. If it has the premium system I can post that if you wish.


1999 Ford Mustang Stereo Wiring
Constant 12V+ Light/Yellow
Switched 12V+ Yellow/Black
Ground Black/Green
Illumination Light Blue/Red
Dimmer n/a
Amplifier Remote Blue
Antenna Right Front
Front Speakers 5" x 7" Doors
Left Front (+) Orange/Light Green
Left Front (-) Light Blue/White
Right Front (+) White/Light Green
Right Front (-) Dark Green/Orange
Rear Speakers 5" x 7" Rear Deck
Left Rear (+) Gray/Light Blue
Left Rear (-) Tan/Yellow
Right Rear (+) Orange/Red
Right Rear (-) Brown/Pink




wiring chart for the premium package.

+12V DC Battery(Constant) Lt.green/violet To radio pin C280-1 & CD changer pin C281-4 Audio 10 amp Battery junction box
Switched Accessory Black/pink 32 15 amp Central junction box
Ground Black Also black/light green
Remote Turn On(output) Orange/lt.blue To CD changer, pin C281-5
Illumination Lt.blue/red
Mute Dark blue
Left Front + Light green Line level output
Left Front - White/orange Line level output
Right Front + White/red Line level output
Right Front - Brown Line level output
Left Rear + Lt.blue/black Line level output
Left Rear - Yellow Line level output

AMPLIFIER OUTPUTS
Wire Function Color Note Fuse # Size Location
12V DC Battery Violet/lt.blue Amplifier pin C274-14 & subwoofer amps (notes) 27 25 amp Central junction box
Left Front Mid + Orange/lt.green
Left Front Mid - Lt.blue/white
Right Front Mid + White/lt.green
Right Front Mid - Dk.green/orange
Left Rear Mid + Gray/lt.blue
Left Rear Mid - Tan/yellow
Right Rear Mid + Brown/pink
Right Rear Mid - Orange/red
Subwoofer 1 + Brown/orange To front subwoofer, if equipped.
Subwoofer 1 - Red/black To front subwoofer, if equipped.
Subwoofer 2 + Lt.green/black To rear subwoofer, if equipped.
Subwoofer 2 - Lt.blue/red To rear subwoofer, if equipped.

AT SPEAKERS
Wire Function Color Note
Subwoofer 1 + Black/lt.green To each front super sound speaker (if equipped)
Subwoofer 1 - Black/white To each front super sound speaker (if equipped)
Subwoofer 2 + Black/lt.green Rear subwoofer speakers are separate in the convertible.
Subwoofer 2 - Black/white Rear subwoofer speakers form a unit in the coupe.
 

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These vehicles came equipped with either a premium sound or super sound package. If its premium sound there is only 4 speakers (2 front, 2 rear). If it is Super sound it is equipped with 8 speakers (convertable) or 6 speakers + subwoofer(coupe).

On the premium sound system, the stock stereo sends all its audio signals to an amplifier. This amplifier sends audio to the 4 speakers.

On the super sound system there are 3 amplifiers. Stereo sends audio to the first amp, which sends audio to the 4 regular speakers. This amp also sends audio to the left rear speaker subwoofer amplifier and the right rear speaker subwoofer amplifier.

Is this vehicle still equipped with the stock radio/stereo/cd player? or is it aftermarket?

Sounds like either the stereo is bad or the stock amplifier is bad. Have replaced these before.

-ford tech

PS if you need wiring diagrams, let me know.
 

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Discussion Starter · #5 ·
stock premium sound system (cd player, speaker in each door and two in rear deck).

I think the only reason why we notice the loss/lack of bass in the passenger side now is because the new speakers actually produce bass.

What should I look for??
common problem to lose bass in passenger half of car??
 

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stock premium sound system (cd player, speaker in each door and two in rear deck).

I think the only reason why we notice the loss/lack of bass in the passenger side now is because the new speakers actually produce bass.

What should I look for??
common problem to lose bass in passenger half of car??

Like I said, its probably the stock head unit, the wiring from the head unit to the amplifier, the amplifer, or wiring from amplifier to right side speakers. I have seen amps go on these mustangs before and they cause weird problems.
 

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Heres everything you need.




 

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Seriously good info here, but I almost insist that it's the stock head unit. Let's think about it for a second. You said:
stock premium sound system (cd player, speaker in each door and two in rear deck).
which leads me to believe that there isn't an amplifier in the entire system. So, we're talking about two wires leading to each speaker in the system. If the right side of the car (ballance) is bad, then it can't be the amp.
If the car had the MACH system, then there is a stock amp in the system.

This is a simple work around though if you don't want to change out the deck. Simply wire the front speakers to the right front, and the rear speakers to the right rear. Change the output from stereo to mono and, no more problem! Now, you won't have that surround sound, but all speakers will have the same sound. You still have the fade function, but your ballance would be useless.
 

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UH OH! now I am lead to believe it DOES have an amp?!?!
 

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Discussion Starter · #11 ·
I was under the understanding that the MACH system has 3 amps and the stock "premier" sound system has only one.

The head unit will be most likely replaced soon (just out of want) with a new one and the stock amp bypassed. but I will do the testing to narrow down the problem first
 

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Hey Scott! Did you ever figure out what the problem was?
 

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Discussion Starter · #13 ·
Didnt even continue working on it...just decided its time for a full system upgrade anyways so its time to get a new head unit and ditch the stock stuff.
Hopefully that should fix it...if not..then its time for electrical testing.
 
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