Honda 2007 Acura RL User Manual page 18

2007 Acura RL
2005-08 ACCESSORIES AND EQUIPMENT Navigation System - RL
Fig. 7: Vehicle Speed Pulse Diagram
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Charge Signal, Navigation Unit Cooling Fan Operation and Trip Computer
The PCM sends a charge signal to the navigation unit via F-CAN. A thermister inside the navigation unit
monitors the units internal temperature. This information combined with a charge signal determines the
control units internal cooling fan operation. The navigation system displays trip computer information that is
calculated by the gauge assembly.
Fig. 8: Charge Signal, Navigation Unit Cooling Fan Operation And Trip Computer Diagram
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Yaw Rate-Lateral Acceleration Sensor
The yaw rate-lateral acceleration sensor (located in the navigation unit) detects the direction change (angular
speed) of the vehicle. The sensor is an oscillation gyro built into the navigation unit.
Sensor Element Structure
The sensor element is shaped like a tuning fork, and it consists of the piezoelectric parts, the metal block,
and the support pin. There are four piezoelectric parts: one to drive the oscillators, one to monitor and
maintain the oscillation at a regular frequency, and two to detect angular velocity. The two oscillators,
which have a 90-degree twist in the center, are connected at the bottom by the metal block and supported by
the support pin. A detection piezoelectric part is attached to the top of each oscillator. The driving
piezoelectric part is attached to the bottom of one oscillator, and the monitoring piezoelectric part is attached
to the bottom of the other oscillator.
Oscillation Gyro Principles
The piezoelectric parts have "electric/mechanical transfer characteristics. "They bend vertically when
voltage is applied to both sides of the parts, and voltage is generated between both sides of the piezoelectric
parts when they are bent by an external force. The oscillation gyro functions by utilizing this characteristic