2003 RDS aftermarket no sound
 

Well....I bought an aftermarket stereo for this blazer and hooked it up and have no sound. Ugh. Stock headunit (kinda) worked, has docks for two wiring harnesses, but there was only one hacked up main harness connected (thanks previous owner 😑). I wired the harness for the new stereo and there are still three or four wires not connected. Powers up, connects to my phone, no sound.
I'm seriously about to burn this bitch to the ground. Anyone encounter this before

The factory radio has two plugs; one will be the main connector that has power, ground, acc, illumination, and the 4 speaker channel outputs, as well as wires for factory steering wheel controls and a communication wire that links the radio to the BCM, and maybe a couple other wires I'm forgetting about. The second plug is, if I'm not mistaken, for the optional tape deck that some have mounted in the front part of the center console. If you don't have the tape deck down there, it makes since that nothing was plugged into it.

"Stock headunit (kinda) worked", how so? Why "kinda"? What did it do, or not do?

So you say behind the factory radio "there was only one hacked up main harness connected", as in the original plug was cut off at one time and spliced back on maybe?

I can only think of a couple scenarios that would make the radio not work:
A) the aftermarket radio you're trying to install is no good...
B) when a factory radio plug was spliced back on, the wires were not matched correctly
C) you're new harness is not wire-matched properly


To my knowledge, no Blazer ever came with a factory amp, so that shouldn't be the issue. Even the 6 speaker systems with the tweeters on top of the dash still only had 4 channels, the tweeters were just part of the front channel. You should, in the end, end up with 12 wire connections to hook up a basic aftermarket radio:

1) YELLOW - Constant 12+
2) BLACK - Ground
3) RED - IGN 12+
4) ORANGE - Illumination 12+ (don't worry about "dimmer", I have yet to see an aftermarket radio that actually uses dimmer in the 20 years I've been playing with stereo equipment...)
5) WHITE - Left front +
6) WHITE W/ STRIPE - Left front -
7) GREY - Right front +
8) GREY W/ STRIPE - Right front -
9) GREEN - Left rear +
10) GREEN W/ STRIPE - Left rear -
11) PURPLE - Right rear +
12) PURPLE W/ STRIPE - Right rear -

BLUE - Optional, amp remote turn on
BLUE W/ STRIPE (WHITE OR BLACK USUALLY) - Also optional, used in cars with power raising antennas, not something you'll use on any S series...

If it's a unit with a screen and has things like a backup camera and DVD playback or navigation, then you end up with a couple more wires like pink for the parking brake sense and green for the reverse gear sense.