The RTD system is bi-state real time damping, two corner
rear leveling (if equipped), and a electronic variable orifice, (EVO) power
steering system, (if equipped).
The RTD system consists of the following:
• | Suspension Control Module |
• | Compressor/Leveling Module |
• | Steering Handwheel Speed/Position Sensor |
• | Electronic Variable Orifice (EVO) Solenoid |
The objective of the suspension control module is to provide ride and
handling results that are superior to a passive damper system, both on and
off road at all load conditions. The suspension control module monitors
body-to-wheel height, vehicle speed, handwheel position/speed, lift/dive
status and a driver tow/haul input switch status in real time and instantly
selects a "normal" or "firm" mode. This is done
for each of the front and rear shock absorbers in order to adjust the
vehicle for specific road and driving conditions.
The suspension control module will use the rear body-to-wheel displacements
and vehicle speed inputs to keep the rear trim height of the vehicle at its
desired level. This is done to optimize suspension geometry, headlight
aiming, ride travel and keep the vehicle visually level. The system utilizes
the compressor motor relay and the compressor/leveling module which contains
the exhaust solenoid, pressure sensor and compressor motor. The vehicles's
rear leveling compressor motor is switched ON and OFF via a compressor
motor relay which is controlled by the suspension control module. The suspension
control module provides a switched path to ground whenever compressor activity
is required. The suspension control module supplies 5 volts to the
RTD air pressure sensor. The pressure sensor uses this reference voltage
to produce an analog output of approximately 0.15 to 4.85 volts.
The signal voltage is a reference of the air pressure in the rear leveling
system. The exhaust solenoid valve is switched ON and OFF via the suspension
control module. The suspension control module provides a switched path
to ground whenever the exhaust "head relief" sequence occurs
at compressor start-up (If system pressure is lower than 10 psi).
The suspension control module also uses the steering handwheel position/speed
sensor and vehicle speed inputs to control a power steering effort control
valve. The suspension control module varies the steering assist by adjusting
the current flow through the electronic variable orifice (EVO) solenoid
control circuits. The amount of steering assist is dependent upon vehicle
speed and input from the steering handwheel position/speed sensor. As the
vehicle speed increases, the steering assist decreases and the driver effort
increases. As the vehicle speed decreases, the steering assist increases
and the driver effort decreases.
The shock solenoid valve is driven ON and OFF by the suspension control
module. To activate the solenoid, it is initially subjected to full battery
voltage for a short period of time. Once the solenoid is pulled-in, the
supply voltage is pulse width modulated (PWM). The amount the shock solenoid
valve is activated is based on inputs from the driver Tow/Haul switch,
road inputs and the PCM. The suspension control module provides a common
ground (low reference) for all 4 of the shock solenoid valves.
The suspension control module provides a common regulated voltage of
approximately 5 volts to all four of the (body-to-wheel) position sensors,
RTD air pressure sensor and the steering handwheel position/speed sensor.
The suspension control module receives VSS from the PCM and over the class
2 circuit. The position sensors provide an analog signal voltage between
0.5 and 4.5 volts to the suspension control module. This signal
voltage represents the wheel's position relative to the body. The suspension
control module provides a 5 volt reference and a low reference to
the position sensors.