FORD 2013 Explorer v.1 - Manual (Page 117)

Brake system warning light
To confirm the brake system warning light is functional, it will
momentarily illuminate when the ignition is turned to the on
position when the engine is not running, or in a position
between on and start, or by applying the parking brake when the ignition
is turned to the on position.
If it illuminates when you are driving, check that the parking brake is not
engaged. If the parking brake is not engaged, this indicates low brake
fluid level or a brake system malfunction. Have the system checked
immediately by your authorized dealer.
WARNING: Driving a vehicle with the brake system warning light
on is dangerous. A significant decrease in braking performance
may occur. It will take you longer to stop the vehicle. Have the vehicle
checked by your authorized dealer as soon as possible. Driving
extended distances with the parking brake engaged can cause brake
failure and the risk of personal injury.
Charging system (RTT)
Illuminates when the battery is not charging properly. If it stays
on while the engine is running, there may be a malfunction with
the charging system. Contact your authorized dealer as soon as
possible. This indicates a problem with the electrical system or a related
component.
Door ajar (RTT)
Displays when the ignition is on and any door is not completely
closed.
Engine oil pressure (RTT)
Illuminates when the oil pressure falls below the normal range.
Instrument Cluster 117
2013 Explorer (exp)
Owners Guide gf, 1st Printing
USA (fus)