OEM Radio pin layout
 

We have a Monsoon system that I've changed to a aftermarket unit. Once I did this is seems the sub-bass is now much lower. I'm wondering if the OEM radio has other pins that are used which go to their Factory unit.


Any Ideas?

Re: OEM Radio pin layout
 

Joe,
You must have (Merta GMOS-04) wiring harness to retrain the monsoon system & chim features www.merta.com then connect the wires as specified in the manual.

CONNECTIONS TO BE MADE ON THE 24 PIN
GRAY HARNESS:
1. Connect the yellow wire to the radio?s 12V battery or memory wire.
2. Connect the red wire to the radio?s ignition or accessory wire.
3. Connect the black wire to the radio?s ground wire.
4. Connect the orange wire to the radio?s illumination wire. If the wire is not present, tape up wire.
5. Connect the orange/white wire to the radio?s dimmer wire. If the wire is not present, tape up wire.

CONNECTIONS TO BE MADE ON THE 14 PIN
HARNESS
1. Connect the blue/white wire to the radio?s AMP turn-on wire.
2. Connect the red wire to the radio?s Igniton or accessory wire.
3. Connect the RCA cables to the radio?s RCA outputs. If no RCA outputs are
available, use the Metra line output converter part #ALO-648 (SOLD SEPARATELY).
4. The white RCA goes to the left front RCA output of the radio.
5. The gray RCA goes to the front right RCA output of the radio.
6. The green RCA goes to the left rear RCA output of the radio.
7. The purple RCA goes to the right rear RCA output of the radio.

The following wires on the 14 pin harness are for the aftermarket radios that have navigation
built in:
1. Connect the Brown wire to the mute wire of the aftermarket radio.
2. Connect the Green wire to the parking brake wire of the aftermarket radio.
3. Connect the Blue/Pink wire to the VSS or speed sense wire of the aftermarket radio.

ONSTAR LEVEL ADJUSTMENT
To adjust the Onstar volume level find the Brown wire that you cut on the 16 pin harness, you will use
the Brown wire that is by itself, with no other wire with it. Push the blue Onstar button, while the voice
is speaking tap the Brown wire to ground. There are 4 volume settings for Onstar; once the 4th setting
is reached and the Brown wire is tapped to ground it will automatically go back to the first volume setting.
Once the volume is set it will stay at that volume until the Brown wire is tapped to ground again.
This can be set during installation and then left alone. If user adjustment is desired, a momentary contact
switch (sold separately) can be added. Connect one terminal from the switch to ground and the other terminal
to the brown wire. The volume will change one level every time the switch is pressed.
4. Connect the Green/Purple wire to the reverse wire of the aftermarket radio.

Hope I Helped You

Re: OEM Radio pin layout
 

Thanks, Bought a few off ebay but before that I picked up this:
http://www.pac-audio.com/instructions/c2r-gm24.pdf

Now once this was installed did anyone else have issues with loosing their sub-bass in the front and rear with their monsoon sytem??