Manual Transaxle

PURPOSE
When activated, the Speed Control System maintains vehicle road speed at a driver-selected rate.

OPERATION
Using input information from the Vehicle Speed Sensor and the Speed Control Servo feedback potentiometer, the Speed Control Amplifier varies the level of vacuum applied to the Speed Control Servo. The Speed Control Servo, in turn, operates the engine throttle linkage to speed up or slow down the vehicle.

Voltage is present at the Speed Control Switch Assembly "ON" contacts at all times through the HORN Fuse, the Horn Relay coil, and the Slip Ring Assembly.

With the Ignition Switch in "START" or "RUN", voltage is present at the Speed Control Amplifier through the METER Fuse.

Speed Control Amplifier Inputs
Speed Control Switch Assembly
The Speed Control Switch Assembly signals the Speed Control Amplifier to turn the system on and off, to set and hold the vehicle speed, and to accelerate or coast.

Switch Modes
With the Switch held "ON", voltage is applied to pin E, C234, of the Amplifier.

In "OFF", pin E is grounded.

With the Switch held in SET/ACCEL, a 680 ohm resistor is placed in the ground circuit.

In RESUME, a 2200 ohm resistor is placed in the ground circuit.

In COAST, a 120 ohm resistor is used.

Stop Lamp Switch
With the brake pedal and clutch pedal NOT depressed, the Speed Control Amplifier is grounded at pin F, C234, through the Stop Lamps.

With the brake pedal depressed, the Stop Lamp Switch contacts close and voltage is present at pin F. This input electrically removes the ground from pin F and causes the Amplifier to disengage the System.

Clutch Interrupt Switch
With the clutch pedal depressed, the Clutch Interrupt Switch contacts open, interrupting the ground circuit that the Amplifier monitors through the Clutch Interrupt Switch and the Stop Lamps. This input causes the Amplifier to disengage the System.

Vehicle Speed Sensor
The Vehicle Speed Sensor (VSS) is a permanent magnet generator driven by a transaxle gear. Sensor output is proportional to vehicle road speed. With Sensor output indicating that vehicle road speed is above 30 mph, the Speed Control Amplifier enables the Speed Control System.

The Vehicle Speed Sensor signal is also used to maintain vehicle speed when the System is operating.

Speed Control Servo
The Speed Control Servo contains a potentiometer connected to the throttle linkage. The Speed Control Amplifier applies a reference voltage to the potentiometer and monitors the voltage of the return signal. This feedback circuit provides information about throttle linkage position.

Speed Control Amplifier Outputs
Speed Control Servo
With the Speed Control System turned on and vehicle road speed above 30 MPH, the Speed Control Amplifier energizes the Vacuum and Vent Valves in the Speed Control Servo. The Vacuum Valve passes vacuum to the Speed Control Servo, where it is used to move the throttle linkage. The Vent Valve controls the level of vacuum applied to the Servo.

Vacuum Dump Valve
The Vacuum Dump Valve provides a mechanical means of disengaging the Speed Control System. With the brake pedal released, the Valve is closed, and the vacuum level in the System is determined by the Vent Valve. With the brake pedal depressed, the Valve opens, disabling the vacuum circuit.