Circuit Description
The Cruise Control System is a speed control system that maintains a desired vehicle speed under normal driving conditions. The cruise control system has the capability of the following:
| • | Cruise |
| • | Coast |
| • | Resume speed |
| • | Accelerate |
| • | Raise (Tap-up) the vehicle speed by 1.6 km/h (1 mph) |
| • | Lower (Tap-down) the vehicle speed by 1.6 km/h (1 mph) |
The PCM controls the cruise system. When the cruise control switch is in the ON position and you push the cruise SET/COAST switch, the PCM maintains the current vehicle speed. If the engine load varies, the PCM commands the throttle blade to the appropriate position in order to maintain the desired vehicle speed.
The cruise control system consists of the following components:
| • | Powertrain control module (PCM) |
| • | Throttle actuator control (TAC) module |
| • | Throttle body/TAC assembly |
| • | Cruise control actuator lever |
Conditions for Enabling the Cruise System
| • | The cruise switch is in the ON position. |
| • | The ignition voltage is between 9 and 16 volts. |
| • | Ignition voltage is present to the cruise actuator lever. |
| • | The vehicle speed is more than 39 km/h (24 mph). |
| • | The engine speed is between 550 and 5900 RPM. |
| • | The clutch or brake pedal is not depressed. |
| • | The transmission is in a forward gear other than first. |
| • | The vehicle is not in a traction control event. |
| • | The engine is not in Engine Coolant Over Temperature-Fuel Disabled mode. |
| • | The engine has been running for more than 5 seconds. |
Conditions for Disabling the Cruise System
| • | The cruise switch is turned to the OFF position. |
| • | Ignition voltage is interrupted to the cruise actuator lever. |
| • | The vehicle speed is less than 39 km/h (24 mph). |
| • | The clutch or brake pedal is depressed. |
| • | The engine is in Engine Coolant Over Temperature-Fuel Disabled mode. |
| • | The transmission is placed into neutral. |
| • | A problem with the clutch or brake pedal switches or circuits that the PCM module interprets as the pedal is applied. |
Diagnostic Aids
Use the scan tool in order to monitor the Cruise Disengage History. This parameter lists the last 8 cruise disengage events. Refer to Cruise Disengage History table for a description of each condition.
The cruise control system disables for the current ignition cycle if an intermittent condition exists and DTC P0567 or DTC P0568 sets.
Scan Tool Display | Definition |
|---|---|
ALDL | The PCM detects the scan tool has sent a inhibit message via serial data. |
Bad Memory | The cruise system has detected a RAM corruption. |
Brake | The PCM detects one of the brake switches active (TCC Brake Switch/Cruise Control Brake Switch or Stop Lamp Switch). |
Pedal Initialize | The PCM does not detect the brake switch active during an ignition cycle. (Auto Trans only) |
Cancel | The PCM detects the cruise cancel switch has been depressed. |
Clutch Switch | The PCM detects the clutch has been depressed. |
Coast Disengage | The PCM senses the vehicle speed is greater than 8 km/h (5 mph) below the set speed or the coast button is depressed for longer than 3 seconds. |
Coast Speed Low | The Set/Coast switch is pushed and held until vehicle speed drops below 32 km/h (20 mph). Vehicle speed below 32 km/h (20 mph) will disable the cruise system. |
Eng Run Time | The PCM has detected the engine has not been running for longer than 5 seconds. |
Eng Speed | The PCM has detected the engine speed is not between 550 and 5900 RPM. |
TAC Inhibit | The PCM has detected that an Electronic Throttle Control fault is active. |
DTC Set | The PCM has detected DTCs P0500, P0502, P0503, P0560, P0567, P0568, P0571, P0704, P0719, P0724, P0751, P0753, P0756, P0758, P0785 or P1574 are present. |
Accel Rate | The vehicle acceleration is greater than the expected acceleration rate which is calculated by the PCM. |
Decel Rate | The vehicle deceleration is greater than the expected deceleration rate which is calculated by the PCM. |
High Speed | The PCM detects that the vehicle speed is greater than 225 km/h (140 mph). |
Illegal CC Mode | The PCM will not allow cruise with the current position of the cruise switches. |
INJ Disable | The PCM detect the Fuel Disable Mode is active. |
Low Speed | The PCM detects that the vehicle speed is less than 39 km/h (24 mph) when cruise enable is attempted. |
Man Neutral CC | The PCM has detected the transmission is in neutral. |
MPH Limited | The PCM has detected that high speed fuel cutoff has been reached. |
Cruise Off | The PCM does not detect that the cruise enable switch is active. |
Over Set Speed | The TAC module detects that the vehicle speed is greater than the cruise memory speed by more than a predetermined amount or, the vehicle speed is greater than a predetermined value during a transient maneuver, such as, Resume, Accel, Tap-up or Tap-downs etc. |
S/C On-Speed High | This parameter is displayed when the Set/Coast switch is applied (tap down vehicle speed) and the vehicle speed is greater than the cruise memory speed by more than a predetermined value. For example, if the cruise control system is set to maintain a vehicle speed of 48 km/h (30 mph) then the vehicle is accelerated to 80 km/h (50 mph) and you depress the Set/Coast again, the S/C On-Speed High message appears in the Cruise Control Disengage History. |
Simul SC/RA Sw | The PCM detects the Set/Coast and Resume/Accel switches are active at the same time. |
Traction Loss | The PCM module detects the vehicle is in a Traction Control event. |
Under Set Speed | The PCM detects that the vehicle speed is less than the cruise memory speed by more than a predetermined amount or, the vehicle speed is less than a predetermined value during a transient maneuver, such as, Resume, Accel, Tap-up or Tap-downs etc. |
First Gear | When the PCM detects the vehicle is in first gear. |
Pedal Greater CC | The PCM senses the accelerator pedal is at a greater value than the commanded cruise position for more than 1 minute. |
Ignition Volts | The PCM detect voltage out of the range of 9 to 16 volts. |
Trans | The PCM detect the transmission is not in forward gear higher than 1st gear (auto trans) or the clutch is depressed (manual trans). |
Wheel Speed Low | The PCM has detected the driven (rear) wheels are at a greater speed than the front wheels. |
Wheel Speed High | The PCM has detected the driven (rear) wheels are at a lower speed than the front wheels. |
MPH Governor | The PCM detects the vehicle has reached 190 km/h (118 mph). |
RPM Governor | The PCM detects the engine has reached 5900 RPM. |
