I recently replacement a factory stereo in a 05 trailblazer. i purchased a Gmos-04 transmitter for my onstar and door chime.. upon completion of the installation i noticed that the sound was not on the sound was very low and faint meaning that the amp had not been triggered and is not on.. could someone please assist me with this because u cant figure it out for the life of me and i did follow the diagram..

Don't think there is a remote turn on. I think this vehicle uses a data bus instead. A metra gmos-04 is required to keep the factory amp, chimes and on star.

This seems the setting change in the player set to factory setting and then see if you face the same problem please use this

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It is likely the radio needs to be pulled out and sent to a factory approved repair center, the parts are not available to the public.

You need to talk to the experts on auto sound issues like this one.
www.crutchfield.com

It's not the receiver, it's the interface. If you recently had this unit installed with a door chime or, some other type of LAN data interface to replace the door chimes, the adjustment is off. The interface/door chime needs to accessed to turn the volume down.
The interface is neccessary because when you remove the factory stereo from a newer GM vehicle you lose the door chimes, accessory 12 volt power source, ON Star, etc. The LAN data interface replaces these features when adding an aftermarket stereo.

it is possible to replace the radio in your car with a aftermarket unit using the following metra parts

Dashkit - 99-3301
wire harness - GMRC-04 non onstar interface
wire harness - GMRC-05 onstar interface
antenna adaptor - 40-gm12

It will fit, but the parts are expensive and it is not plug and play.

Parts needed:

Dash kit- Metra 99-3305 About $15-$20

Antenna adapter- Metra 40-CR10 (Chrysler antenna adapter) Yes GM uses Chrysler parts. About $10-$15

Wire harness/Interface- GMOS-LAN-01 (non bose or onstar) About $100
GMOS-LAN-02 (bose/onstar) About $120

The reason for the pricey harness is to retain data features on the vehicle and to interface with Onstar (GMOS02).

This is the right way so don't cut corners because it can cause issues on your brand new vehicle.

All of your safety chimes run through the stereo and not using the correct interface can cause issues with your gauges

www.metraonline.com or www.scosche.com are good sources for install parts info

you don't need all those wires . Just connect what you have and the gmos will simulate the rest

take vehicle to local chevy dealer and have radio unlocked,only option

Do a search on line you can download for free...