How does odometer and trip meter retain mileage with no battery.

True for a generic tone ring. I'm fairly certain the Tacoma uses an active tone ring as it senses on the side rather than the tip of the ABS Sensor.

Magneto-resistive sensor – These sensors use a magnetic encoder ring similar in appearance to the encoder ring associated with the hall sensor. However, the encoder ring associated with this sensor has magnetic arc segments which cause a clear change in resistance when passing the sensor. It is this that enables the control unit to determine the wheel’s rotational direction. Magneto-resistive sensors are much more precise, but generally more expensive than Hall sensors and require a less precise installation position, therefore meaning that it can be located further away from the ‘ABS ring’ than the other types of sensors.

Both active sensors are less sensitive to electromagnetic interference, vibration and temperature fluctuations than a passive sensor.

Active sensors
An active sensor still detects the movement of a magnet by either blocking the magnetic field with a rotating vane style tone ring or by detecting the change in North/South poles of the magnet. These sensors don’t generate voltage like passive sensors. Instead they require power to the semiconductor chips and report either a digital or analog signal.

 

nice info. I’ve not dug that far into the info for directional sensitive sensor, that’s good to know. I’ve dealt with speed probe and vibration sensors in large equipment and machinery and never thought much about reverse rotation. Makes sense on what you have posted and I would think most auto manufacturers these days have figured out the tweakers tricks of driving in reverse to lower your odometer mileage lol

 

It was a joke...

 

riiiiiight

 

https://www.youtube.com/watch?v=L_o_O7v1ews

 

Bro, tracking....here is a clip of me and the boys trying it. Got into some heat that day let me tell you.