Teensy 4.1 with CANBUS adapter and flexcan t4 - no CAN data stream?

The CAN lines are on the OBD port, yes they go thru a gateway too. Could be 1 or 2 other busses that's on. You have also a body CAN bus, which is nice, because it has data available while the vehicle is off.
You could always bypass the gateway and go directly to the other busses if you have the wiring info of your vehicle

vehicle doesnt need any termination at all as they have their own, in some circumnstances it can cause the dash to light up for some vehicles, false positive errors on the bus
you'll need to check your haltech if it has resistors built in, and if it does they should have a way to disable it in programming
Screenshot_20230430-211731_Samsung Internet.jpg
programming resistor on haltech

also if you're asking about a custom configuration, there should be max 2 resistors in a bus 120ohms each furthest device. if you do remove the 120 ohm from your transceiver and you do need a termination later on just add a 120ohm resistor later on

if you don't plan on doing dual CAN, take the resistor off one side, and keep the one on the other side
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