12V or 5V?

You're using a 12V supply, and I'm sure the AiM dash requires 12V, but doesn't CAN typically run on < 5V logic?

What voltage do you run on your 4 pin Deutsch connectors 12V or 5V? (not for this example, but you've mentioned a HPA standard 4 pin for CAN)

CAN is only two wires. If they are using a 4pin connector then 2 of the pins will be power to the device and two will be the CAN. Most CAN devices designed for automotive use such as displays, lambda controllers, EGT amps etc would require a 12V supply.

The CAN is a differential signal with both wires floating around 2.5V for a dominant bit (logical1), to send a recessive bit (logical 0) the CAN high goes up to about 3.5V and CAN L drops to about 1.5V.