Cruise Control System Description Gas
The cruise control system associated with the gasoline
engines includes the following components:
| • | The vehicle control module (VCM) |
| • | The cruise control module |
| • | The cruise control cable |
| • | The multifunction lever |
| • | The brake release switch |
| • | The clutch release switch (manual transmission) |
The cruise control module operates in the following manner:
| • | The cruise control module contains a stepper motor. |
| | The stepper motor is used to change throttle position. |
| • | The cruise control module receives commands from the multifunction
lever. |
| • | The cruise control module receives vehicle speed from the VCM. |
| • | The cruise control module uses the multifunction lever and the
VCM in order to control speed. |
Brake Release Switch
The cruise control module uses an electronic brake switch which contains
one normally open switch contact and one normally closed switch contact.
These contacts are part of the zero adjust brake switch.
When the brake pedal is depressed, the two brake switch contacts change
input states at the cruise control module. The cruise control module then
shuts off all the cruise control outputs.
Clutch Release Switch
For vehicles equipped with a manual transmission, the clutch release
switch is on the clutch push-rod. When the clutch pedal is depressed, the
clutch release switch activates and interrupts the voltage supply to the
cruise control circuit in the engine control module, and disengages the
cruise module.
Vehicle Speed Signal
The vehicle speed sensor (VSS) generates the vehicle speed signal at
the transmission. The VCM translates the VSS.
The VSS mounts to the automatic transmission assembly. The VSS produces
an AC signal. The frequency of this signal is proportionate to the transmission
output shaft speed. The AC signal goes to the VCM for amplification and
conversion to a digital square wave that represents the vehicle speed
in terms of pulses per mile (ppm). The VCM provides a 4000 PPM
signal.
This 4000-PPM signal is available to the cruise control module, and
the speedometer in the instrument cluster.
Cruise Control System Description Diesel
The cruise control system associated with diesel engines
includes the following components:
| • | The powertrain control module (PCM) |
| • | The electronic throttle system |
| • | The vehicle speed sensor (VSS) buffer |
| • | The multifunction lever |
| • | The brake release switch |
The PCM operates in the following manner:
| • | The PCM receives commands from the multifunction lever. |
| • | The PCM receives vehicle speed information from the VSS buffer. |
| • | The PCM sends information to the electronic throttle system in
order to control vehicle speed. |
Brake Release Switch
The PCM uses an electronic brake switch which contains one normally
open contact and one normally closed contact. These switch contacts are part
of the zero adjust brake switch.
When the brake pedal is depressed, the two brake switch contacts change
input states at the PCM. The PCM then shuts off all of the cruise control
outputs to the electronic throttle system.
Clutch Release Switch
For vehicles equipped with a manual transmission, the clutch release
switch is on the clutch push-rod. When the clutch pedal is depressed, the
clutch release switch activates and interrupts the voltage supply to the
cruise control circuit in the engine control module, and disengages
the cruise module.
Vehicle Speed Sensor
The VSS generates the vehicle speed signal at the transmission. The
VSS buffer translates the vehicle speed signal.
The VSS mounts to the automatic transmission assembly. The VSS produces
an AC signal. The frequency of this signal is proportional to the transmission
output shaft speed. The AC goes to the VSS buffer for amplification and
for conversion to a digital square wave that represents the vehicle
speed in terms of pulses per mile (PPM). The VSS buffer provides a 4000-PPM
signal.
This 4000-PPM signal is available to the PCM, and the speedometer in
the instrument cluster.
