FoMoCo Whelen Sapphire in a GM vehicle

[AlphaZulu]

Hello,

I've been trying to set up a second hand Whelen ConCom Sapphire in my 2017 Tahoe SSV and am having trouble with the horn ring. I have it set up as show in the attachment and while the unit is powered on it functions exactly as I'd expect, however when I power it down the factory horn honks continuously. I've tried switching the wires on the off chance I had them reversed, but that simply makes the horn ring do nothing at all whether powered on or off.

Does anyone know what I'm doing wrong or how to fix it? This is my first time setting up a system this fancy.

 

[NoLimitSquads]

You are back feeding ground back to your vehicles horn. How exactly are you wired into the sapphire? Are you using the cencoms dry contact relay? Or an external relay?

 

[AlphaZulu]

It's currently wired using the factory 50 amp service to the main power inputs and an always hot wire to the "ignition" input. I want to be able to run with unit with the vehicle off, so I don't have that tied to an actual ignition switch wire, but I added a switch inline to cut that power when needed. This causes the factory horn to sound continously.

 

[NoLimitSquads]

How is the horn wired?

 

[AlphaZulu]

Factory supplied horn wire is attached to the two horn ring wires on the unit, nothing fancy.

 

[NoLimitSquads]

Factory supplied horn wire is attached to the two horn ring wires on the unit, nothing fancy.

I need to know exactly how, as this is most likely the reason that you are having a problem. You should have the horn switch side of your wire to the orange, pin #6, and the vehicle horn to the red pin # 7. Then brown pin #8 should be connected to the white/yellow horn ring input. You said, the two horn ring wires. There is only one horn ring wire, so Im not sure what you are hooked to, but that is probably where your backfeed is coming from.

 

[AlphaZulu]

I see what you mean. The horn ring wire has a large factory provided loop in it between the BCM and horn relay. That wire has been cut and fed into pins #9 & #11 (white yellow and yellow). The front mounted siren speaker is connected to pins #6 & #13.

The only thing I can't be certain of is which end of the horn ring wire goes to the BCM and which goes to the horn relay, but if I reverse the connections from how I currently have them there is no function from the horn ring at all.

 

[NoLimitSquads]

That wire has been cut and fed into pins #9 & #11 (white yellow and yellow).

This right here is the problem. That yellow wire is for triggering an external relay.
For figuring out which side of the vehicle horn loop to use, tap each end of the wire to ground, which ever side sounds the horn, is the bcm side. The other side of the wire is the switch side. If you still want to retain you factory horn, and not use an external relay, do as follows;
Connect the horn switch side to the Orange wire in the plug that has all the outputs. Connect the bcm side to the red wire in the same plug. Then take the brown wire next to those wires, and connect it to the white/yellow wire that you are currently using. In Command, you will have to turn on the dry contact relay when you want the hands free to work. Also the fuse on the top of the cencom needs to be in the dry contact position.

 

[AlphaZulu]

Oh, ok. I'll have to dig into it and and get that changed up, but that makes sense. Thanks for all your patient help!

 

[NoLimitSquads]

Oh, ok. I'll have to dig into it and and get that changed up, but that makes sense. Thanks for all your patient help!

No problem. If you need the high current outputs on the cencom, you can achieve this same thing using an external 5 pin relay. But instead wiring the horn switch side to pin 30 of the relay, the horn bcm side to pin 87a, the white/yellow horn ring input to pin 87, and that yellow horn transfer wire to pin 86. Pin 85 will be grounded.

 

[AlphaZulu]

I'm going to tear into this on Saturday when I have some free time, but I just looked through the command software and wanted to confirm something beforehand.

I'm currently using outputs 1, 2, 3, 5, 6, & 7. I didn't see anything in there about turning on the dry contract relay, would that be enabling output 8 when in a mode that I want the horn ring to be active on, or did I miss it somewhere?

Thanks again, I don't think I would have ever figured this out.

 

[AlphaZulu]

Upon double checking it outputs 1, 2, 3, 4, 5, 6, just in case that makes a difference.

 

[NoLimitSquads]

It’s been awhile since Ive programmed a Sapphire, but Im pretty sure its output 8. And yes, just turn that on when you want it to switch from factory horn to hands free.