Stereo Install, Power But No Sound?

[iblue]

Ok, so I just installed a new JVC CD Player into the wifes 88 LX Convertible Mustang. It powers on when you move the key into the on position and switches off (with its cute little goodbye message) when you remove the key so the power wiring is all in order. However, when I attempt to play radio or CD, there is no sound output.

I checked the two fuses (6 and 11 if memory serves) that are listed as being involved with the radio according to the fuse panel cover. I used a volt meter on the left front speaker (in dash) and got 23mV of power when the car is switched on, 0mV when off. However, it does not increase/decrease with the volume being turned up and down. The volt meter on the left rear (in interior 1/4 panel) reads 0mV no matter what.

The following info may/may not aid responses.

- The previous factory AM/FM radio had worked just fine
- I have just replaced the entire interior
- The car has now been converted to a mass air setup (hey, its wiring changes!)
- The car previously had an alarm in it
- The car has 6 speaks (two in dash, two in doors, two in interior 1/4 panels)

I have the wiring diagram made by tmoss from veryuseful.com but I dont know if this Mustang has premium sound or not. Any help/troubleshooting advice would be very appreciated!

*edit*

I just snagged the connector packs (for 86-whatever Fords) from Best Buy and wired them color to color as stated in the instructions. There isnt something weird with these cars that would cause you not to wire it color/color is there? Also, I did not connect up the blue/white and blue wires for power antenna and whatever else. Those run to the connector that supplies power and not the speaker connector anyways.

 

[Daggar]

Here's my first guess. I'm sure others will follow:

It sounds as if you may have at least ONE speaker power wire shorted to ground. You should be getting more than 23 Milivolts. The amp may be shutting off (if that head unit is equipped with that feature) or you're sending the 1+ volts straight to ground somewhere.

Good Luck

 

[HISSIN50]

My first thought was to wonder if the factory amp was not dealt with, does that kill the sound? It seems like it would.

Good luck and bump.

 

[Blk91stang]

Interesting, I'm suffering from the SAME problem right now in my stang. Aftermarket radio came in my car when I bought it and worked great. Now out of the blue, when I hit bumps, the volume turns on and off (I can shake the headunit by punching the side of it to mimic the bumps but it never works) with the same exact symptoms you are talking about.

I'm another one in this boat so... TTT!

 

[dastang2]

Interesting, I'm suffering from the SAME problem right now in my stang. Aftermarket radio came in my car when I bought it and worked great. Now out of the blue, when I hit bumps, the volume turns on and off (I can shake the headunit by punching the side of it to mimic the bumps but it never works) with the same exact symptoms you are talking about.

I'm another one in this boat so... TTT!

you just need a new radio, mine did that, i had to beat it up so it would stop turning all the way up when it was turned on. if there is a factory amp then that is your problem. speakers in cars with amps won't work without the amp i have heard.

 

[iblue]

Daggar, I will check the speaker wires to look for shorts. Thanks for the troubleshooting tips.

Everyone else, where is the factory amp located? Also, I thought only the "premium stereo" upgrade had the factory amp. If this is true, how do I tell if this particular cas has the premium sound? Its an LX but it is also a convertible so I have no clue.

Thanks!

 

[Daggar]

It's beneath the center speaker grill on the dash pad.

 

[Saleen0679]

Everyone else, where is the factory amp located? Also, I thought only the "premium stereo" upgrade had the factory amp. If this is true, how do I tell if this particular cas has the premium sound? Its an LX but it is also a convertible so I have no clue.

IIRC, if you have a six speaker system you should have a premium sound system. On an 88 the amp is located behind the radio mounted in a 'U' shaped bracket. Also, when changing to an aftermarket head unit I remember some of the guys talking about having to use an amp bypass harness or else you don't get any sound.

Also, you might want to search the Sound Shop forum. I remember seeing some threads about the subject in there at one time.

Here's one of the threads http://forums.stangnet.com/showthread.php?t=567230

 

[Daggar]

Actually, I think Saleen is right on. I remember someone else saying something about that amp being in a different location in cars later than mine.

 

[Blk91stang]

you just need a new radio, mine did that, i had to beat it up so it would stop turning all the way up when it was turned on. if there is a factory amp then that is your problem. speakers in cars with amps won't work without the amp i have heard.

Did I buy your car?? Nothing crazier than the volume going to max randomly and sometimes hard to shut off short of pulling the face off of it.

Sorry for the quick hi-jack. TTT for ya!

 

[midlife89]

amp for sure,had the same problem when I changed my factory stereo

 

[iblue]

IIRC, if you have a six speaker system you should have a premium sound system. On an 88 the amp is located behind the radio mounted in a 'U' shaped bracket. Also, when changing to an aftermarket head unit I remember some of the guys talking about having to use an amp bypass harness or else you don't get any sound.

Also, you might want to search the Sound Shop forum. I remember seeing some threads about the subject in there at one time.

Here's one of the threads http://forums.stangnet.com/showthread.php?t=567230

Ohhh, thats what that thing is. I thought it was a computer for the AOD or something. Okay, so I need to bypass the amp, cool! Sounds simple enough. Thanks guys!

:SNSign:

 

[iblue]

Great, new problem.

Ok, so I bypassed the factory amp. Apparently you just remove the amp and unplug the 8-pin square connectors on top of it, then trace those wires back until you find them plugged into another set of 8-pin rectangular connectors. You then unplug that set of connectors and plug in your stereo harness to that instead of the 8-pin rectangular ones that the stock stereo uses.

But apparently, bypassing the factory amp means you dont get sound to your door speakers. I have read this in a few other threads, wondering if anyone else can confirm this? Should I just trace the speaker wires for the doors back and splice them into the wires for the dash speakers or just go buy a small aftermarket amp to power the door speakers?

Argh.

 

[5.0 con-vert]

Did you get the wiring harness to bypass the factory amp or are you cutting/pasting everything back together? I know wires get real weird between the two old harnesses. I had the same setup in my vert and I had to spend the extra ten bucks to get the harness from Crutchfield. I haven't had any problems since. Just my .02.

 

[billpo]

It is definately the amp. I had the same problem. like they, there is a bypass harness. I just paid 40 bucks at a stereo install place to get it fixed.

 

[iblue]

Did you get the wiring harness to bypass the factory amp or are you cutting/pasting everything back together? I know wires get real weird between the two old harnesses. I had the same setup in my vert and I had to spend the extra ten bucks to get the harness from Crutchfield. I haven't had any problems since. Just my .02.

I had purchased another bypass harness but it was the wrong one. So I called Metra tech support and they harness number they gave me (70-1770) was the exact same style as what I had already bought from Best Buy. Do you remember how yours looked? Currently my setup looks like this from what I remember. I will double check and snap some pics tonight:

8 pin rectangular plug to stock head unit (grey) - UNPLUGGED
8 pin rectangular plug to stock head unit (black) - UNPLUGGED
8 pin square plug to stock amplifier (grey) - UNPLUGGED
8 pin square plug to stock amplifier (grey) - UNPLUGGED
8 pin rectangular plug to stock amplifier (grey) - PLUGGED to aftermarket head unit harness
8 pin rectangular plug to stock amplifier (black) - PLUGGED to aftermarket head unit harness

When you used the Crutchfield harness did you use both the rectangle plugs or one of the rectangle plugs and one 8 pin square plug?

God when I get this all figured out I am going to do a howto on this one....