Radio 97 gmc k3500 factory radio wiring for aftermarket

[Jandel 1313]

I have a 97 gmc k3500 with the factory radio with cassette built in and aux cd player. I started replacing it with an after market but I get no sound from the speakers. The factory harness for the radio input has an additional purple w/ white stripe, solid dark green, and dark green with white stripe. According to all the wiring diagrams these are not speakers as those are other colors. I am wondering if any of these could be for a factory amp, reserves indicator, one of the key1 or key 2 connections, or power antenna (even though the antenna is static)? 
 

update found a lot of info after continuing searches. 

here you go (credit to the12volt.com)
Constant 12V+ Orange
Switched 12V+ Yellow
Ground Black
Illumination Gray
Dimmer n/a
Antenna Right Front
Front Speakers 4" x 6" Dash
Left Front (+) Tan
Left Front (-) Gray
Right Front (+) Light Green
Right Front (-) Dark Green
Rear Speakers 4" x 6" Side Pillar
Left Rear (+) Brown
Left Rear (-) Yellow
Right Rear (+) Dark Blue
Right Rear (-) Light Blue

I have seen this on nearly every forum and search i could find. I am wondering does anyone know about the other wires on the harness? On the upper half the plug it has orange, yellow, grey, purple with white, black, tan, grey, light green, dark green . The bottom half has, brown, yellow, dark blue, and light blue, solid green, and green w white stripe No sound on aftermarket with power and functions not muted. Does anyone knows what the other three wires on the top half goes to?

Update I found this on another post purple w white dimmer, green w white vss, & dark green serial data. Still no clue on where to hook up the serial data. I think it may turn on the factory amp. Any ideas?

The after market harness. 

Edited June 8, 2025 by Jandel 1313
Update

[davester]

would have suggested using a harness adapter instead of hacking up the factory harness.

 

charm.li should have wiring diagrams and connector pinouts you can use.

[richard wysong]

Some times the rear of the factory radio is stamped with a diagram

[Jandel 1313]

20 hours ago, richard wysong said:

Some times the rear of the factory radio is stamped with a diagram

I check it does not have the diagram on the head unit.  I did figure out the purple w/White is dimmer, solid green is serial data, and green with white is VSS (increase volume at speed).  Not of those are on the new radio.  I just need to figure out is one of those will activate the factory amp and which wire on the radio would be best to use.  i am thinking ignition switch power.

thanks for taking time to respond.  

[Jandel 1313]

I would have preferred a harness adapter but was not able to find one that is compatible.  I am fortunately able to repin the wires in the original harness.  

 

Great call a charm.li I was able to verify all of the wires.  So the search for a compatible harness continues.

Thanks

[Gunner41]

Have you checked Crutchfield? I picked up one for my 97 3500 on Ebay myself.