This is completely a different installation compared to the Montana 2004.
You need to cut the vdata, so make sure wires are not reversed as this sends out the Passlock value which allows starting.
Also make sure the YELLOW wire of the EVO is on ACCESSORY and not ignition. This is why you cannot program the unit correctly.
The wire you need to cut at the transponder is the main power, red/white. Pin locations will vary per model.
If you want to test your installation, you need to manual jump some wires in this order.
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Ground the GwR
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put 12V to accessory
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put 12V to ignition
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remove 12V from accessory (car should crank here)
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put 12V back to accessory
If accessory and ignition are powered at the same time, the vehicle will never crank.