2005 Blazer Stereo Question's

[hellionhell]

I'm looking into replacing the headunit and speakers in my 2005 Blazer. I'm looking for clarification regarding some things that various stores have told me.

For reference my Blazer has the AM/FM/CD/Cassette 2-DIN Non-Bose headunit.

They say that a rather expensive bypass module is needed for this model year. They told me the headunit runs several items including the airbags. I've been looking this up on the net and the only mention I find states that the Blazer headunit only controls the door chime. I'd prefer to lose that anyway.

Does anyone here know for sure what the headunit in the 2005 model years controls?

Also does anyway know the wire color codes for the connector on these headunits?

I've tried searching the forum but haven't been able to find an answer that's already been posted.

[JC327]

The module is somehow connected to the airbag system, and it also emulates the switched (accessory) power circuit to the radio. Not using the module can also cause problems with the on-board diagnostic system.

If you try to hook an aftermarket radio directly to the wiring harness, it will not turn on as there is no actual accessory power there. The sytem can be rigged to work by running your own accessory power to the aftermarket unit, but as the other problems will still be there, it is not advisable to do so.

[Jon Teeter]

I believe the you can get the bypass kit for $80-$100.Check ebay you may be able to get it cheaper.It may be expensive but will save you on other headaches.

[blazer_guy86]

I have a 98 and all i had to do to put in an aftermarket radio was buy a little 10$ wiring adaptor to kook up my new headunit. I didn't notice anything different. I'm not for sure but i think it messes with the keyless entry system but i don't have that anyway.

[JC327]

Originally Posted by blazer_guy86

I have a 98 and all i had to do to put in an aftermarket radio was buy a little 10$ wiring adaptor to kook up my new headunit. I didn't notice anything different. I'm not for sure but i think it messes with the keyless entry system but i don't have that anyway.

The '98 and the '05 are quite different in regards to the radio and other electronics systems. GM began using a different method in 2001, and most of their vehicles made after that year require the databus adapter that has been mentioned when adding an aftermarket radio.

[hellionhell]

Originally Posted by JC327

The module is somehow connected to the airbag system, and it also emulates the switched (accessory) power circuit to the radio. Not using the module can also cause problems with the on-board diagnostic system.

If you try to hook an aftermarket radio directly to the wiring harness, it will not turn on as there is no actual accessory power there. The sytem can be rigged to work by running your own accessory power to the aftermarket unit, but as the other problems will still be there, it is not advisable to do so.

Well I decided to take a shot at this without a bypass module just to see what would happen. After removing the stock headunit I noticed absolutely no change in the vehicle. Passes all startup checks, including airbag. Even the door chime still plays. I still would like to know where it is so I can unplug it.

So I decided to put in the new headunit. Alpine CDA-9857. Worked perfectly. The wire marked for accessory power on the cable harness I bought is a switched +12V line. So the stock wiring does bring accessory power to the headunit.

As this is the first time I've replaced a car stereo it took me all weekend, but my new stereo and speakers are installed and working perfectly. I didn't require a bypass module or have to find an accessory power line.

I also have an OBD-II connector (www.autoenginuity.com). It's able to connect to the vehicle perfectly with the new stereo installed and finds no problems.

Thanks for the advice.