Components Of The System
The GR II system consists of the following components:
MAIN SWITCH (Up to 9/97) - The main switch is mounted on the right side of the dash panel below the instrument cluster. It produces a momentary ground signal to the GR II control module. When pressed the GR II control module switches on and the cruise enable indicator lamp in the instrument cluster (green in color) is illuminated.
After 9/97 the main switch was deleted and combined with the "OFF" switch located on the MFL.
CRUISE CONTROL SWITCH - The cruise switch pad is mounted on the right side of the steering wheel.
All of the request functions ( SET, ACCEL, DECEL, RESUME AND OFF) are activated from the cruise switch pad.
These request inputs are processed by the switch and transmitted to the Steering Wheel Control Module (MFL-CM) over a data link.
STEERING WHEEL CONTROL MODULE -
Up to 9/96 the MFL-CM is mounted on the left side of the steering column behind the left side knee bolster. After 9/96 the MFL -CM is integrated into the right button pad.
The cruise control requests are processed and transmitted to the GR II cruise control module over a dedicated data link.
CRUISE CONTROL MODULE - The cruise control module is mounted in the E-box between the DME and AGS control modules.
It has one blue 26 pin ELO type connector. CRUISE CONTROL ACTUATOR - The cruise control actuator is mounted on the left fender well and contains the actuator motor, feedback potentiometer and actuator clutch.
The actuator is connected to the throttle valve with a bowden cable parallel to the accelerator cable.
COMPONENT COMMUNICATION:
The cruise control switch pad provides momentary ground signals and converts them into a dynamic digital signal.
The signal is sent to the steering wheel control module and passed through a gateway to the GR II control module.
The GR II carries out the systems functions based on this dynamic digital signal and other input signals.
The actuator is controlled by final stage activation at both sides of the motor.
CRUISE CONTROL SWITCH OPERATION:
When the main switch is turned on and the vehicle speed is above 20 mph, the cruise control can be set or adjusted at the cruise control switch pad.
RESUME: Briefly pressing the resume button will cause the vehicle to accelerate/decelerate to the stored speed value in the cruise control module.
SET/ACCELERATE/TIP-UP: Pressing the set button will engage the cruise system and maintain the vehicle's current speed.
Pressing and holding the set button cause the vehicle to accelerate. When released, the vehicle's current speed will be the set speed.
Tapping the set button will cause the speed to increase by approx. 1 MPH. The number of times the tip feature will function is limited to 8.
OFF: Pressing the off button will disengage the cruise control. The previous set speed is stored in memory until it is overwritten or the vehicle is switched off.
In addition to switching off via the cruise control switch on the steering wheel, the system can also be switched off by:
DECELERATE/TIP-DOWN: Pressing and holding the decelerate button will cause the vehicle to slow down. When the button is released, the current speed is the new set speed. Tapping the button will cause the vehicle speed to decrease by approx 1 MPH. The number of times the tip feature function is limited to 8.
- Depressing the main switch on the instrument panel.
- Applying the brakes.
- Shifting the transmission into neutral.
CRUISE CONTROL MODULE :
The cruise control module contains control logics for smoother operation. The control logics prevents the maximum acceleration/deceleration feel that was characteristic with the earlier FGR system.
The rate of acceleration in SET ACCELERATE and RESUME is based on the current road speed of the vehicle. The rate of acceleration is high at low vehicle speeds and gradually decreases as vehicle speed increases. This gives the feeling of steady smooth acceleration.
The rate of deceleration when the DECELERATE button pressed is linear until the throttle valve closes. The decel rate is then dependent on the engine braking effect and road conditions. This results in a smooth speed reduction.
If the set speed can not be maintained due to unusual operating conditions (severe up hill grades), the control module adopts a special resume mode. Once the unusual operating condition is overcome, the set speed will be resumed at a reduced acceleration rate. This feature is designed to prevent a sensation of rapid accelerating.
The cruise control module is connected to the AGS control module through a data link. When cruise control functions are activated, the AGS shift program is adapted to match the requirements of the requested cruise control function. For example, when the GR II is set at a specific speed and a severe down hill grade causes the vehicle to overcome the set speed the GRII signals the AGS to downshift a gear. This will occur as needed to maintain the set speed as closely as possible.