Cruise Control – HFV6
Page 8C–6
The stop lamp switch contacts are normally open with the brake pedal at rest and close when the brake pedal is pressed
turning on the vehicles brake lamps. These switch contacts also double as the cruise cancel signal for the cruise control
operation.
The cruise control initial brake apply signal function switch contacts are normally closed with the brake pedal at rest and
open when the brake pedal is pressed. This switch function is a safety requirement of the vehicle as it ensures that the
cruise control cannot be activated without the brake pedal first being pressed.
Powertrain Interface Module
The Powertrain Interface Module (PIM) is located on the driver’s side, kick trim panel. The purpose of the PIM is to act as
an interface between the drivetrain serial data bus (GMLAN protocol) and the body side data bus (UART Bus protocol).
All inputs from the cruise control switch assembly are directly wired to the PIM. The PIM then takes these inputs,
converts them to GMLAN protocol and sends the messages via the data bus to the engine control module (ECM). The
PIM also receives signals for the cruise control system from the ECM. When the ECM activates cruise control, it sends a
signal through the PIM (which converts it from GMLAN to UART protocol) to display the various cruise control messages
on the instrument cluster assembly.
For further information on the operation of the PIM, refer to 6E1 Powertrain Interface Module – V6.
Engine Control Module
The Engine Control Module (ECM) is mounted on the front of the engine. The role of the ECM is to receive all the inputs
from various sensors (vehicle speed (VSS) etc.) and switches to manage the engine. When a request is sent from the
cruise control switch assembly via the PIM to the ECM, the ECM will activate cruise control providing given parameters
are satisfied. Once the cruise is set, the ECM monitors the vehicle speed and controls the throttle actuator assembly thus
controlling the speed of the vehicle.
For further information on the operation of the ECM, refer to 6C1-1 Engine Management – V6 – General Information.
Throttle Actuator Control (TAC) Assembly
The throttle actuator control assembly is located on the front of the inlet manifold. The throttle actuator control assembly
receives signals from the ECM and controls the angle of the throttle plate. Refer to 6C1-1 Engine Management – V6 –
General Information for further information.
1.3
System Operation
Preliminary Information
Enabled and Disabled
The cruise control is enabled / disabled by pressing the cruise control ON–OFF switch mounted on the lower right hand
side of the dash panel. When cruise control is enabled, the cruise control ON–OFF switch illuminates and the cruise
control is ready for a speed to be set (cruise control activated). When the cruise control is disabled, the cruise control
cannot be activated.
Cruise Enabled
1
The cruise control ON–OFF switch (1) supplies 12
Volts to the Powertrain Interface Module (PIM) when it
is pressed.
2
The cruise control ON–OFF switch lamp (2) turns on.
Cruise Disabled
1
When cruise control ON–OFF switch (1) is pressed
again, power is removed from the PIM disabling the
cruise control.
2
The cruise control ON–OFF switch lamp (2) turns off.
Figure 8C – 4