Troubleshooting a backup battery

I installed a dei battery backup in my truck.  It does keep the alarm siren working after the battery is disconnected, but disconnecting the battery itself does not trigger the alarm.  I disconnected the connector on the backup module and I grounded out the blue trigger wire.  This does set off my alarm.  The black wire (next over) reads continuity to ground.  I did not test the middle two because if I remember correctly, these two run to the backup battery itself.  The gray wire read about 12 volts and the red wire read about 12 volts ( with the vehicle battery still connected).  I had spliced the red wire to constant power, and the gray wire to the power input to the alarm brain.  I assumed the two middle wires were good because they weren't spliced, and the battery itself works.  I don't have the schematic but Im pretty sure everything is wired correctly.  Does this sound like the backup module itself has gone bad?  I bought it off of Ebay, but it was in original packaging.  I really don't even care that the trigger function doesn't work, I just need the battery itself to act as a backup, but it's annoying that I took time to hook it up completely and that function doesn't work.  Any help is greatly appreciated.

Blue wire off of the BUB goes to the -instant trigger of the alarm.Certified Security Specialist

Always check info with a digital multimeter.

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I have the blue wire hooked up to the (-) Multiplexed Input, Zone 4.  It says it goes to Optional Sensor, and it's Blue, from a 550 esp alarm.  I don't see anything on the schematic that says - instant trigger.

Well, it should be working. Is the there anything else going to the -trigger wire?Certified Security Specialist

Always check info with a digital multimeter.

I promise to be good.

Tell Darwin I sent you.

I've been sick lately, sorry I won't be on much.