Help! Installing Relay with GMOS-04

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Jul 6, 2008 | 03:11 PM

openhelix

Thread Starter

Burning Brakes

Joined: May 2006

Posts: 878

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From: Santa Clara CA

Help! Installing Relay with GMOS-04

I have an 07 C6 (no bose, no onstar) and am trying to get the GMOS-04 harness setup. It says I need to use a relay (I have a ratshack 275-001 as per the FAQ) however I'm not sure now where to mount it. The wiring instructions are outlined in the gmos-04 instructions but do I need to mount the relay in the under hood fuse box? where should I get power from and run ground to?

Thanks!

BTW, I searched and checked the FAQ, nothing specific on where to put the relay or how to wire it up.

Jul 6, 2008 | 03:58 PM

TheKomoman

Le Mans Master

Joined: Jun 2004

Posts: 9,289

Likes: 16

From: Skippack PA

St Jude Donor '13

Quote:

Originally Posted by openhelix

You wire it in with the GMOS-04 in the dash. I thought I did include this copy & paste from the Metra install instructions:

Quote:

A Relay is needed in the 2005-2007 Corvette. You will need to cut the blue/white wire in half
between the 16 way Molex and 24 way gray connector.
• Connect the blue/white wire coming from the 16 way Molex to pin 85 of the Relay.
• Connect the blue/white wire coming from the 24 way connector to pin 30 of the Relay.
• Connect pin 86 of the Relay to Ground.
• Connect pin 87 of the relay to fused 12 volt constant wire. Using tape or a wire tie securely the
Relay from moving around in the dash.

That tells you exactly what you need to do with the relay & the GMOS-04.

Jul 6, 2008 | 04:00 PM

openhelix

Thread Starter

Burning Brakes

Joined: May 2006

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From: Santa Clara CA

Thanks komoman. I was thinking I needed to put the relay in the fusebox for some reason. I wired it up with some quick connects.

Pin 87 connected to the yellow wire on the harness with a T-tap and Pin 86 to the black ground wire.

Jul 6, 2008 | 11:04 PM

pentavolvo

Le Mans Master

Joined: Nov 2004

Posts: 8,718

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From: Dyer IN

Cruise-In IX Veteran

gmco is the ideal harness for a nonbose/nononstar FYI in case u continue to have issues

Feb 19, 2009 | 09:44 PM

Weasel 435

Advanced

Joined: May 2008

Posts: 55

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From: Kent Washington

Quote:

Originally Posted by openhelix

I'm doing a similar install on my C6, and in the instructions it says to use a SPDT relay, whereas that item number leads to a SPST relay. I've been looking high and low for a SPDT as per the instructions, but I can't seem to find any. Where should I be looking for such a part, and is it necessary to use a SPDT, or will a SPST serve a similar function?

Feb 20, 2009 | 02:43 PM

Jimmy 2 Times

Burning Brakes

Joined: Oct 2003

Posts: 1,079

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From: east norriton pa

the GMOS-04 comes with a relay

Aug 23, 2011 | 07:21 AM

sajonf

Burning Brakes

Joined: Aug 2006

Posts: 887

Likes: 2

Quote:

Originally Posted by TheKomoman

You wire it in with the GMOS-04 in the dash. I thought I did include this copy & paste from the Metra install instructions:

A Relay is needed in the 2005-2007 Corvette. You will need to cut the blue/white wire in half
between the 16 way Molex and 24 way gray connector.
• Connect the blue/white wire coming from the 16 way Molex to pin 85 of the Relay.
• Connect the blue/white wire coming from the 24 way connector to pin 30 of the Relay.
• Connect pin 86 of the Relay to Ground.
• Connect pin 87 of the relay to fused 12 volt constant wire. Using tape or a wire tie securely the
Relay from moving around in the dash.

That tells you exactly what you need to do with the relay & the GMOS-04.

I am installing this setup in my 2011 with Bose and the instructions for the GMOS-04 and the relay have a discrepancy.

As shown above the GMOS instructions say to connect the GMOS side (16-way) of the blue/white wire to pin 85 of the relay and connect pin 86 of the relay to ground.

My relay shows pin 85 is ground (black) and pin 86 is 12v switched. They are basically reversed from the GMOS instructions.

So should I assume that my relay is wired differently than the GMOS instructions state? I would think they should all be pretty standard but maybe not.

If I take that approach here is how it would be wired:

Car side (24 pin) of blu/wht wire - connect to pin 30 of relay (yellow - described as common)

GMOS side (16 pin) of blu/wht wire - connect to pin 86 of relay (described as +12V power)

Connect pin 85 of relay (black - described as ground) to ground

Connect pin 87 of relay (brown - no description - normally open, connected to #30 when coil is energized) to yellow 12V constant

Is this correct? Any help would be appreciated. Thanks!

Aug 23, 2011 | 09:26 AM

markcz

Tech Contributor

Joined: May 2003

Posts: 7,035

Likes: 134

From: North Augusta, SC

Pins 85 & 86 are the coil, one needs to be grounded and the other is the controlling wire (remote trigger from gmos). It doesn't matter which one is connected where.

Pins 30 & 87 are the 'switch'. Connect one of them to battery and the other to supply whatever equipment you're powering. Again it doesn't matter which one is where.