Another amplifier/aftermarket HU question

[Shashing]

Hello, I picked up an '03 Vibe GT last week and it's already been.. interesting. Sorry for making this my first post here I haven't seen this answered through my searching. So the car came with a JVC head unit installed, not the greatest thing but it works mostly.. I get full sound through the front speakers but the backs are very quiet and the tweeters have no sound. Turns out the amplifier from under the passenger seat is missing completely, the harness is there but nothing else. I wired in my alpine head unit the exact same way as the jvc and it'll power up and works fine but has no sound at all.
I just bought a used amplifier from ebay so hopefully that solves the problem but it's strange that the jvc powers the fronts and sort of the backs, from any wiring diagrams I've found the power only gets to the speakers through the amp. If anyone has advice on this it would really be appreciated. Thanks

-I should add, the car has no sunroof and no factory subwoofer.

[kaflex]

I have the 03 GT also, love the car. I stuck in a Pioneer HU and no audio at first, didn't realize the car had a factory amp, so I didn't connect the blue remote, after connecting that blue wire I had full audio. To me IMO what it sounds like they did with the JVC was spliced right into the speaker wires to get audio, and bypass the amp. Was there a harness used?

[Shashing]

Yes there is a harness used, it has a second blue connector hanging off it doing nothing. Both headunits were used with the same harness witht the same wires so it's strange. The remote wire is hooked up too, though not having an amp there it probably isn't doing much at the moment.

[SeattleJeremy]

Here's a basic wiring diagram. Disregard the subamp and cap.
http://forums.justcommodores.com.au/att ... iagram.gif" onclick="window.open(this.href);return false;

Is the second blue cable the one that's actually connected to the amp? Maybe it's a simple matter of connecting that one.

The head unit should not be directly connected to the speakers. Head units are smart enough to turn off the internal amp when powered RCA cables are connected to them.

Headunit -> RCA cables front and rear -> Amp -> speakers.

Remember to used fused power line and ground the amp properly. Is the fuse in good working order?

Edit: Might be best to trace all the wires to make sure they're going to the places you're expecting them to

[dannyy72]

I did a write-up a while back that might help you out a little. Take a look.

viewtopic.php?f=28&t=38740" onclick="window.open(this.href);return false;

[Shashing]

Well I got the factory amp in the mail, plugged it in and there's no change. I only have the one big plug coming up out of the floor with no sign of the second one, I'm assuming that's for the factory sub that mine doesn't have. The next step is probably tracing every speaker wire but that job pretty much sucks.

[Derf]

This is from a moon and tunes package, not sure if the wire colors are the same, bottom of post has excel sheet with wire colors going to speakers. Might at least help isolate the wires you are looking for.
viewtopic.php?f=11&t=40421" onclick="window.open(this.href);return false;

Someone will have to clarify, reading previous posts, the base Vibes lack the sub and tweeters. That said I was not able to confirm if the base package still had the speaker grate sail panels, or solid blanks in their place. So if you are not hearing the tweeters, either the car does not have them, or the aftermarket items from the previous owner need attention.