Quick GMOS-04 Relay Question
Tech Contributor
Joined: May 2003
Posts: 7,035
Likes: 134
From: North Augusta, SC
Bypass the GMOS with the trigger, connect the HU blue wire directly to the amp, problem solved 
If your radio has an 'antenna trigger' connect it to B3 on the big radio plug (or the wire on the interface side of the plug) so it will trigger the oem antenna module to power up. If no dedicated antenna trigger use the same trigger as amp on B3.
If your radio has an 'antenna trigger' connect it to B3 on the big radio plug (or the wire on the interface side of the plug) so it will trigger the oem antenna module to power up. If no dedicated antenna trigger use the same trigger as amp on B3.
Instructor
Joined: Feb 2012
Posts: 204
Likes: 5
Ok, I will give it a try. I figure the trigger would only work if the radio was on. Right now I used the relay and the beeps suck or are non existant. Chimes are ok. When you hit the lock, unlock, memory seat...etc it only works sometimes. Sometimes its just static.
just to confirm you completely bypass the blue/ white stripe wire coming from the gmos, cut it right out of the loop? Antenna trigger from radio directly to b3 on 24pin connector?
just to confirm you completely bypass the blue/ white stripe wire coming from the gmos, cut it right out of the loop? Antenna trigger from radio directly to b3 on 24pin connector?
Tech Contributor
Joined: May 2003
Posts: 7,035
Likes: 134
From: North Augusta, SC
If you already have it hooked up with a relay, then nothing will change by doing the bypass method. But yes, HU blue/white directly to B3, but you don't need to connect it to the oem wires, use the wire between the GMOS box and 24-pin GMOS plug.
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Instructor
Joined: Feb 2012
Posts: 204
Likes: 5
Problem with the relay is by the time it clicks and turns the amp on the emulated beep is gone. I tried removing the relay and bypassing the gmos. Problem with that method is when the radio is off you get no power to the blue/white wire...meaning the amp is not on. The oem radio seems to activate the amp quickly for the beeps, on or off. Your method, no amp power when radio is off. No amp power no beep
Last edited by turbosl2; Oct 1, 2013 at 09:01 PM.
Tech Contributor
Joined: May 2003
Posts: 7,035
Likes: 134
From: North Augusta, SC
Some adapters play chimes from an internal speaker, GMOS uses external amp and speakers, right? I was thinking it had an internal speaker like C2R-GM24 does. You'll need to keep the relay to get chimes when radio is off.
The relay should engage in under 0.1 second, if the beeps are done by the time you can hear them it's probably because of the amp having a 'soft start' feature so you're not blown away the instant the radio turns on.
The relay should engage in under 0.1 second, if the beeps are done by the time you can hear them it's probably because of the amp having a 'soft start' feature so you're not blown away the instant the radio turns on.
Instructor
Joined: Feb 2012
Posts: 204
Likes: 5
Some adapters play chimes from an internal speaker, GMOS uses external amp and speakers, right? I was thinking it had an internal speaker like C2R-GM24 does. You'll need to keep the relay to get chimes when radio is off.
The relay should engage in under 0.1 second, if the beeps are done by the time you can hear them it's probably because of the amp having a 'soft start' feature so you're not blown away the instant the radio turns on.
The relay should engage in under 0.1 second, if the beeps are done by the time you can hear them it's probably because of the amp having a 'soft start' feature so you're not blown away the instant the radio turns on.
Former Vendor
Joined: Sep 2005
Posts: 18,293
Likes: 137
From: Hazel Green, Wi www.doubledmods.com
St. Jude Donor '12-'13
There is no need for any relay with the gmos04
not needed
do not worry about it
we send out 20-30 packages a week with this harness and install them all the time including my own car
you do NOT need any form of relay.
Everything will work just fine
its as simple as it gets to install
from radio to gmos04
red to both reds
yellow to yellow
black to black
blue white to blue white
blue to blue
green to green
green black to green black
purple to purple
purple black to purple black
white to white
white black to white black
gray to gray
gray black to gray black
the orange white dimming wire to gray with black stripe on traction control harness
there is a black with yellow stripe wire coming from the gmos04 which is used to adjust the volumes by grounding it to something in mounting cage area.
there is a blue dial on gmos o4 as well to adjust volume
This is all there is to it
no relay required
no B3
nothing
will all work just fine when done
our packages we can even wire the Maestro SW module into the gmos04 so you do not even have to cut into car harness at all
not needed
do not worry about it
we send out 20-30 packages a week with this harness and install them all the time including my own car
you do NOT need any form of relay.
Everything will work just fine
its as simple as it gets to install
from radio to gmos04
red to both reds
yellow to yellow
black to black
blue white to blue white
blue to blue
green to green
green black to green black
purple to purple
purple black to purple black
white to white
white black to white black
gray to gray
gray black to gray black
the orange white dimming wire to gray with black stripe on traction control harness
there is a black with yellow stripe wire coming from the gmos04 which is used to adjust the volumes by grounding it to something in mounting cage area.
there is a blue dial on gmos o4 as well to adjust volume
This is all there is to it
no relay required
no B3
nothing
will all work just fine when done
our packages we can even wire the Maestro SW module into the gmos04 so you do not even have to cut into car harness at all
Last edited by Double D Mods; Oct 1, 2013 at 11:05 PM.
Instructor
Joined: Feb 2012
Posts: 204
Likes: 5
There is no need for any relay with the gmos04
not needed
do not worry about it
we send out 20-30 packages a week with this harness and install them all the time including my own car
you do NOT need any form of relay.
Everything will work just fine
its as simple as it gets to install
from radio to gmos04
red to both reds
yellow to yellow
black to black
blue white to blue white
blue to blue
green to green
green black to green black
purple to purple
purple black to purple black
white to white
white black to white black
gray to gray
gray black to gray black
the orange white dimming wire to gray with black stripe on traction control harness
there is a black with yellow stripe wire coming from the gmos04 which is used to adjust the volumes by grounding it to something in mounting cage area.
there is a blue dial on gmos o4 as well to adjust volume
This is all there is to it
no relay required
no B3
nothing
will all work just fine when done
our packages we can even wire the Maestro SW module into the gmos04 so you do not even have to cut into car harness at all
not needed
do not worry about it
we send out 20-30 packages a week with this harness and install them all the time including my own car
you do NOT need any form of relay.
Everything will work just fine
its as simple as it gets to install
from radio to gmos04
red to both reds
yellow to yellow
black to black
blue white to blue white
blue to blue
green to green
green black to green black
purple to purple
purple black to purple black
white to white
white black to white black
gray to gray
gray black to gray black
the orange white dimming wire to gray with black stripe on traction control harness
there is a black with yellow stripe wire coming from the gmos04 which is used to adjust the volumes by grounding it to something in mounting cage area.
there is a blue dial on gmos o4 as well to adjust volume
This is all there is to it
no relay required
no B3
nothing
will all work just fine when done
our packages we can even wire the Maestro SW module into the gmos04 so you do not even have to cut into car harness at all
I added the relay, no improvement.
Former Vendor
Joined: Sep 2005
Posts: 18,293
Likes: 137
From: Hazel Green, Wi www.doubledmods.com
St. Jude Donor '12-'13
we have NEVER used a relay and everything works just fine