Need to know the speaker wiring code from the back of a sony cdx-gt07 car stero

Left Front (+) White Left Front (-) White/Black Right Front (+) Grey Right Front (-) Grey/Black Left Rear (+) Green Left Rear (-) Green/Black Right Rear (+) Violet Right Rear (-) Violet/Black

This model does not have rca outputs on rear. To wire a sub to it you will need a signal processor. You wire speaker lead to box and it will covert signal to an rca output for amp.

It sounds like you have some wiring issues, moreso issues with your speaker wiring, or your speakers. I would first test the speakers, 1 by 1 using a double A, or AA 1.5v battery. Each speaker wire pair should be tested by attaching 1 wire to the negative side of the batter, and momentarily making contact with the other wire to the positive side of the battery. A low popping/scratching sound should be heard from each speaker. If not, replace each defective unit. Also, double check your wires to ensure they are not damaged.

I’m happy to help further over the phone at https://www.6ya.com/expert/jeremy_69f3cc28d95bf514

Check the Wiring, sounds like there may be a crossed wire or possibly a short.

had a search around and found a manual for you to download:

www.retrevo.com/support/Sony-CDX-GT07-Car-Receivers-manual/id/16768bh031/t/2/

try the fuse box, fuse might have tripped

Check your fader control on the unit maybe it has been adjusted to supply more power to the front speakers.

Here is a link to Sony for parts available for your CDX-GT07. Though I don't see a harness as an option here.
https://servicesales.sel.sony.com/ecom/accessories/web/productSearch.do?searchOperation=modelSearch&searchText=CDXGT07
Sony head units normally have either a 9 pin or a 16 pin harness. Here are both links respectfully.
http://www.kb.sony.com/selfservice/documentLink.do?externalId=C285614
http://www.kb.sony.com/selfservice/documentLink.do?externalId=C217600

In the mix of wires there will be a constant wire. this is usually labeled on the back of your deck this is the wire that need to be hooked into the hot wire. this will provide constant power to the radio that will help it keep the time,position on cd when powered off and other info.

if you need anymore help just give me a shout

yellow is always your constant power