The traction control and abs lights are on the whole time on my mates 2009 Transit 350. I scanned it with FordScan and it showed a fault relating to the rear passenger abs sensor, I forget the exact wording of  the error. We checked the wiring visually and nothing obvious found and then cleaned and reconnected and no change. Also checked the hub abs ring which seemed perfect.

Then fitted a new abs sensor and drove it in case it needs to go over 5mph to reset like some cars but lights stayed on dash, then disconnected battery for over 20mins to reset Ecu adn still no change.

Do fords need the abs / traction lights reset via a diagnostics like FordScan after replacing a sensor or should the lights just go out once it detects a proper reading from a new sensor?

I'm not sure how to use the live data feature of FordScan where you can drive and see what each of the 4 abs sensors are doing?

What's the best way to check the wiring to an abs sensor via a multimeter or FordScan, etc...?

Cheers in advance :)

Yes, you need to reset the warning lights (after reading what the codes were for) then if the light comes back on again you still have a fault somewhere else

If the fault code comes back on after resetting it as Dave said then connect up FORScan go to Dashboard, pull up the ABS Module, scroll down and load up the PID's for the individual wheel sensors.

You should then be able to monitor these and a lot of other data while driving. Remember to click on the start button.

There are instructions on the FORScan website for live data recording.