horn output wire on cm6000 brain

I am putting in a compustar cm6000 remote start and the horn trigger output wire does not function. The install manual states that the default setting is a ground pulse, but metering the wire nothing happens when I set off the panic mode, etc.
Everything else seems to be working correctly.

What are you putting your meter on to check that?   Where are you connecting the other meter lead?

I am putting the black lead from my FLuke to pin 17 of connector CN3 which is (-)250ma horn output or "the white wire".
And I am putting the red lead from my Fluke to a +12v voltage source.

I am then triggering the panic function on the cm6000 which is flashing my parking lights by actually activating the negative trigger (-)250ma 2nd parking light output on pin 3 or "the GREEN / WHITE wire" and outputting +12v on the siren wire also known as pin 20 or "the brown wire".
So I believe I know how to use my meter since I can check for a negative trigger for the parking lights correctly.

Do you have an OP-500 programmer to verify POC #8 option?  Have you tried changing Menu 3 - 9 to see if the white wire output changes? 

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Soldering is fun!

Unfortunately I do not have an OP-500.
I did change menu option 3-9 between pulsed and constant and back again and there was no change in my readings. I am afraid that the setting for POC #8 is not in the default from the factory for some reason.
Unit is new out of the box. If I can't get this option working, I may have to take the positive output for the siren and use it to trigger a relay to get a ground for the horn. I just hate to do that, pin 17 should be a negative trigger by default.