Stereo wiring on 2002 Silverado - Hello -- I replaced factory radio in a 2002 Silverado with aftermarket unit (the factory radio connector had been removed). The wiring harness includes ...

Hello -- I replaced factory radio in a 2002 Silverado with aftermarket unit (the factory radio connector had been removed). The wiring harness includes three dark green wires (solid green, no stripe): one is 12V+ (switched by ignition), one is for a speaker, but I'm not sure what the third one is for. All the wiring diagrams I've seen show only two dk. green wires going to the radio.

The harness also has a fourth dark-green wire, but that one has a white stripe, and I believe it is the vehicle speed signal (for the speed-adjusted volume feature probably). I've seen diagrams showing some Silverados having a dk. green "E&C" wire which may be some kind of diagnostic.

Does anyone know what the third solid green wire is for and if it needs to be grounded or just taped off? Thanks.

I dont have a diagram for that year, u could prally goto the electrical section and goto downloads and goto the gmupfitter link and look at their diagrams

Thanks Machster69. GM-UPFitters website is great but, unless I looked in the wrong place, it seems to have electrical schematics only back to MY2003. I think the electrical system was extensively upgraded starting in '03, so the 2003 schematics won't work for my '02 truck.

Crap, ok maybe try a shop manual! They have basic electricals in the rear of the books... Ide consider a radio basic

Heres what you need to make the stereo work, all other unused wires should be taped off.

Radio 12v orange + radio harness
Radio Ground black - radio harness
Radio Ignition dk. green + radio harness
Radio Illumination brown + radio harness
Factory Amp Turn-on orange + radio harness
Notes: The amplifier is behind the glove box.
Power Antenna N/A
LF Speaker +/- tan - gray +,- radio harness
RF Speaker +/- lt. green - dk. green +,- radio harness
LR Speaker +/- brown - yellow +,- radio harness
RR Speaker +/- dk. blue - lt. blue +,- radio harness

OK -- my radio harness has only one orange wire, so the amp turn-on may be the answer for the extra wire -- also, I wasn't aware there might be an external amplifier behind the glovebox. I'll check that. Thanks much Damion! and machster69 too.

I think amp came with bose stereos only(at least thats how it is now i think)

That would make sense, so I'll probably just tape off the extra wire. I'll post a follow up when I get it all working correctly.
Thx again.

anddddddddd..... No follow up