Audio Problem (Almost NO sound)

[Black91SHO]

Vehicle: '91 MTX SHO Plus, 94k miles

OEM Radio: Replaced by any of 3 other, almost new, stock JBL head units.

OEM AMPs: Replaced with almost new, stock JBL amps.

Parts Tested Good: Speakers, AMPs, Head units.

Problem: Radio either puts out NO sound at all, or with one head unit, puts out VERY little sound at full volume.

I don't get it...if everything tests out good, it's GOT to be a fuse or wiring, right? But if it's a fuse, the radio wouldn't even turn on. If it's wiring, I haven't the foggiest idea where that problem lies or how to identify it, exactly. The only other thing I can do is start stripping pieces of wire off and try testing each individual wire, but I'm not sure what each wire is supposed to emit.

If someone could help me out with this, I would be eternally greatful. I'm about to go crazy without a radio. I'm starting to sing to myself in the car, and that'll drive ANYONE insane!

- Brian

 

[30footSHO]

jelloslug... paging jelloslug...

I once was told that the amps differ from 1st to 2nd gens. The difference is that second gen units turn on with a different voltage than first gen ones. I don't recall which was less, but I think it was the second gen versions. If the head units you are using are from second gen SHOs, and the amps are still first gen, that may explain the low volume.

Someone on here should be able to supply a wiring diagram and a better explanation. You should also help us out and tell (if you can) which kind of amps/head units you have. Good luck!

 

[Camarok]

jelloslug... paging jelloslug...

that's the guy to look for!

 

[sethsho]

Do you have the shorting plug installed in the back of the deck?
Just making sure.

 

[UnsungZero]

You're Constant Power (yellow wire) isnt putting out enough or any power.

Try to find another wire thats always hot.

(i piggy backed the cigarette lighter)

 

[jelloslug]

First make sure you are using all 1st or all 2nd gen equipment. They don't mix and match well. Next check for a shorting plug. Most 1st gen style radios don't need a shorting plug in the 6 pin connector but installing one won't hurt if if it's not needed. Check for power at the Amp. Make sure that you are getting a signal at the blue/orange wire at the amp power connector when you have the radio on. This is the amp turn on lead; no signal=no amp. Next check all the bulk speaker connections: 1) The 8 pin connection at the back of the radio. 2) An 8 pin connector under the carpet near the passenger kick panel. 3) At the JBL amp it's self. 4) To the left of the radio inside the dash there is a set of connectors (one gray one black) that looks like the power connecter for the radio, one is power, one for the speakers. If you are getting a faint signal at high volumes it sounds like the shorting plug is missing. I have also had radios with one or more dead channels that did the same thing.