I am not sure how this works. How does the start and stop of these function?
Okay, but what determines when they start and stop? Or if A or B is supposed to be on or off?There is a button on the end of the right side stalk (wipers) that will cycle the one line display on the small EVIC screen (in between the tach and speedo) thru the trip meter information and the date and range. When any of the values for a trip are displayed you can hold the button to reset the trip info for that trip.
On the UConnect 5 radio, press the "more" button and then select trip you can then select A or B and see the trip values. Holding the A or B on the touchscreen will reset the values.
I usually keep the range displayed on the EVIC and use the radio display to see the trip info.
There is a setting to remove the trip B info from the EVIC in the radio settings somewhere. Then the button on the end of the right lever would just cycle thru the A trip info on the EVIC.
All of our vehicles have the UConnect radio, so I don't know the details of this for a vehicle without the UConnect.
Both count up miles from the last reset. Displaying A on the EVIC (my van has UC3) and holding the button on the stalk resets that. Displaying B and holding the button on the stalk resets that. Once reset they begin the count again. They start when the tires move and they stop when the tires stop. They're trip meters for elapsed mileage.
I use B for the economy by the tank. Fill up till the nozzle clicks off, zero out trip B, drive, refill to the nozzle shutoff, and now you have the actual miles traveled and the actual gallons used. Divide miles by gallons and you get miles per gallon. This will usually be 1mpg worse than the computer thinks, due to how the instant mpg is calculated.
I use trip A for the total miles for the week. But my other van uses it for time since last oil change. Since it gives you the hours the engine has been running and the average speed, you could use it for a true engine hours oil change schedule.
You don't really need these to do a mileage check. I keep a small notebook with pen on the dash. Each fill-up gets recorded with date, location, odometer, gallons. There are columns for miles since last fill and mpg which I calculate when I want to. This also makes it easy to calculate at will the mileage or mpg since any given point. If I were anal, I could include a price column.