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Author Topic: Cruise Control 101  (Read 4808 times)
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sperry
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« on: 12/20/04 08:50 AM »

Cruise control operation 101

2002 W/ Electronic Throttle Control
2002 W/O Electronic Throttle Control (below)
2003 & greater, to date. (below)


Cruise Control Description and Operation 2002 (w/ ETC)

Cruise control is a speed control system that maintains a desired vehicle speed under normal driving conditions. However, steep grades may cause variations in the selected speeds. The electronic cruise control system has the capability to CRUISE, COAST, RESUME SPEED, ACCELERATE, and TAP-UP or TAP-DOWN.

The main parts of the cruise control system are:

    * The throttle actuator control module (TAC)
    * The function control switches
    * The stop lamp switch assembly
    * The powertrain control module (PCM)

The cruise control system uses the TAC module to maintain the desired vehicle cruise speed and operation. The TAC and the powertrain control module (PCM) communicate together to vary the throttle opening in each different cruise control mode. The PCM monitors vehicle speed and operates the throttle actuator. The throttle actuator operates in response to the TAC module, to maintain the desired cruise speed. The throttle actuator motor moves the throttle blade. The PCM assembly contains a low speed limit which will prevent system engagement below a minimum speed of 40 km/h (25 mph). The TAC or PCM module assembly are not serviceable.

The operation of the cruise control is through the function control switches located on the multifunction turn signal lever. The cruise control function control switches includes the ON/OFF, SET/COAST, R/A . The switch assembly provides driver control of the cruise control system.

The multiple function stop lamp switch is used to disengage the cruise control. A cruise control release switch circuit and a stop lamp switch circuit are used. The stop lamp switch is mounted to the brake pedal bracket . To disengage the system the driver presses the brake pedal . The speed of the vehicle at brake actuation will be stored in the memory of the TAC module.

With cruise control, the vehicle can maintain a speed of about 40 km/h (25 mph) or more without keeping your foot on the accelerator. When the driver turns off the cruise control ON/OFF switch or ignition switch, the cruise control turns off. The vehicle speed stored in the memory of the TAC module will be lost.

Ignition positive voltage is supplied from the ETC fuse, to the TAC module. The TAC module is grounded to G103. When the cruise control ON/OFF switch is on, ignition positive voltage is applied to the cruise on switch signal terminal of the TAC module. If the driver has not pressed the brake pedal , ignition positive voltage is supplied through the switches, to the cruise control brake pedal switch signal terminals of the PCM. Cruise control is canceled when the driver presses the brake pedal . The stop lamp switch closes, applying battery positive voltage to the stop lamp signal circuit of the TAC module. Voltage is also removed from the brake pedal signal circuit at the PCM. When pressing the SET/COAST button on the multifunction turn signal lever, ignition positive voltage is applied to the set/coast switch signal terminal of the TAC module. When pressing the R/A on the control switch, ignition positive voltage is applied to the resume/accelerate switch signal terminal of the TAC module.

When the cruise switch is in the ON position, and the driver presses the SET/COAST button, the TAC module notifies the PCM that the cruise control is requested. The PCM then checks to see that the cruise control enable criteria is met. If the cruise control criteria has been met the PCM sends a class 2 message to the instrument panel cluster (IPC) to illuminate the cruise light, if equipped

The PCM will inhibit cruise control:

    * When vehicle speed is less than 40 km/h (25 mph).
    * When in PARK, REVERSE, NEUTRAL, or 1st gear.
    * With low engine RPM
    * With high engine RPM, e.g. fuel cut-off
    * When vehicle speed is to high
    * When an over or under charged battery voltage condition exists
    * Antilock brake system/traction control system is active for more than 2 seconds

If the PCM determines that any of the cruise control inhibit conditions are present, the PCM will disengage the cruise control. The PCM accomplishes this through data communication with the TAC module. If the PCM disables the cruise control for an inhibiting event it will record the reason for disengagement in the Disengage Definition data file.

     
Document ID# 658557
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Cruise Control Description and Operation (2002 (w/o ETC)

Cruise control is a speed control system that maintains a desired vehicle speed under normal driving conditions. However, steep grades may cause variations in the selected speeds. The electronic cruise control system has the capability to CRUISE, COAST, RESUME SPEED, ACCELERATE, and TAP-UP or TAP-DOWN.

The main parts of the cruise control system are:

    * The cruise control module assembly
    * The function control switches
    * The cruise control release switch
    * The stop lamp switch assembly
    * The vehicle speed sensor

The cruise control system uses the cruise control module assembly to maintain the desired vehicle cruise speed and operation. The cruise control module assembly has an electronic controller and an electric stepper motor to vary the throttle in each different cruise control mode. The electric controller monitors vehicle speed and operates the electric stepper motor. The stepper motor operates in response to the electronic controller, to maintain the desired cruise speed. The electric stepper motor moves a strap that is attached to the cruise control cable which moves the throttle linkage. The cruise control module assembly contains a low speed limit which will prevent system engagement below a minimum speed of 40 km/h (25 mph). The module assembly is not serviceable.

The operation of the electronic controller is controlled by the function control switches located on the multifunction turn signal lever. The cruise control functional control switches include the ON/OFF, SET/COAST and R/A switch. The switch assembly provides driver control of the cruise control system.

The stop lamp switch controls both the cruise control release signal and stoplamp signal. These signal circuits are used to disengage the cruise control. The stop lamp switch assembly is mounted on the brake pedal bracket. To disengage the system electrically the driver presses the brake pedal. The speed of the vehicle at brake actuation will be stored in the memory of the cruise module.

With cruise control, you can maintain a speed of about 40 km/h (25 mph) or more without keeping your foot on the accelerator. When the driver turns off the on/off switch, or the ignition switch, the cruise control turns off. The vehicle speed stored in the memory of the cruise module will be lost.

Ignition positive voltage is supplied from the cruise fuse, to the cruise control module and cruise control switch. The cruise control module is grounded to the chassis. When the cruise control ON/OFF switch is on, ignition positive voltage is applied to the cruise on switch signal circuit of the cruise control module. If the driver has not pressed the brake pedal, ignition positive voltage is supplied through the cruise control release circuit, to the cruise control release signal terminal of the cruise control module. . When the driver presses the brake pedal, battery positive voltage is supplied from the stop lamp fuse, through the closed stop lamp switch to the stop lamp switch signal terminal of the cruise control module. As this operation occurs, ignition positive voltage is removed from the cruise release signal circuit. When the SET/COAST is pressed on the control switch, ignition positive voltage is applied to the set/coast switch signal terminal of the cruise control module. When pressing the R/A on the control switch, ignition positive voltage is applied to the resume/ accelerate switch signal terminal of the cruise control module.

The cruise control module receives a vehicle speed signal input from the Powertrain Control Module (PCM). In operation, the voltage varies between 0 V and 5 V.

The cruise control module, cruise indicator control terminal, sends a signal to the PCM when cruise is engaged. The cruise control module, cruise cancel signal terminal, is a circuit used by the PCM to inhibit cruise control when conditions inconsistent with cruise operation are present.

After the cruise control engage criteria has been met and the cruise ON and Set/Coast have been commanded, the cruise control module sends a signal to the PCM that the cruise control is engaged. The PCM then send a class 2 message to the instrument panel cluster (IPC) to illuminate the cruise light.

The PCM will inhibit cruise control:

    * When vehicle speed is less than 40 km/h (25 mph).
    * When in PARK, REVERSE, NEUTRAL, or 1st gear.
    * With low engine RPM
    * With high engine RPM, e.g. fuel cut-off
    * When vehicle speed is to high
    * When an over or under charged battery voltage condition exists
    * Antilock brake system/traction control system is active for more than 2 seconds

If the PCM determines that any of the cruise control inhibit conditions are present, the PCM will disengage the cruise control. The PCM accomplishes this by opening the cruise control inhibit/enable signal circuit.
     
Document ID# 658652

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Cruise Control Description and Operation
`03 & greater, to date.

Cruise control is a speed control system that maintains a desired vehicle speed under normal driving conditions at vehicle speeds above 40 km/h (25 mph). Steep grades may cause variations in the selected vehicle speeds.

The following are the main components of the cruise control system:

    * The powertrain control module (PCM)
    * The On/Off switch
    * The Resume/Accel switch
    * The Set/Coast switch
    * The torque converter clutch (TCC)/brake switch
    * The stop lamp switch
    * The throttle actuator control (TAC) module
    * The vehicle speed sensor (VSS)

Cruise Control Engaged

The throttle actuator control (TAC) module monitors the signal circuits of the following cruise control switches:

    * On/Off
    * Resume/Accel
    * Set/Coast

The powertrain control module (PCM) will engage and adjust vehicle speed based on the information received from the TAC module via the UART serial data link. For further information on the TAC System, refer to Throttle Actuator Control (TAC) System Description in Engine Controls - 4.8L, 5.3L, and 6.0L or to Throttle Actuator Control (TAC) System Description in Engine Controls - 8.1L.

The cruise control switches are located on the multifunction/turn signal lever.

Ignition positive voltage is supplied from the 10-ampere CRUISE fuse to the cruise control switch via the ignition 3 voltage circuit. When the normally open cruise control On/Off switch is turned ON, the switch closes and the TAC module detects a high signal voltage on the cruise control On switch signal circuit. When the normally open set/coast switch is pressed, the switch closes and the TAC module detects a high signal voltage on the cruise control set/coast switch signal circuit. To engage the cruise control system, turn the On/Off switch ON and momentarily press the Set/Coast switch. The TAC module sends a UART message to the PCM, in order to confirm that the cruise control enable criteria has been met. The PCM will engage the cruise control system and record the selected vehicle speed. The PCM sends a class 2 message to the instrument panel cluster (IPC) in order to illuminate the cruise control indicator. Pressing the accelerator pedal, while the cruise control system is engaged, will allow the driver to override the cruise control system in order to accelerate the vehicle beyond the current set vehicle speed. When the accelerator pedal is released, the vehicle will decelerate and resume the current set vehicle speed. The driver can also override the current set vehicle speed via the set/coast switch and the resume/accel switch. When the cruise control system is engaged, pressing and holding the set/coast switch will allow the vehicle to decelerate from the current set vehicle speed without deactivating the cruise control system. When the set/coast switch is released, the PCM will record the vehicle speed and maintain the vehicle speed as the new set vehicle speed. When the cruise control system is engaged, momentarily pressing the set/coast switch will allow the vehicle to decelerate at 1.6 km/h (1 mph) increments for each time that the set/coast is momentarily pressed, with a minimum vehicle speed of 37 km/h (23 mph). When the normally open resume/accel switch is activated, the switch closes and the TAC module detects a high signal voltage on the cruise control resume/accel switch signal circuit. Activating and holding the resume/accel switch, when the cruise control system is engaged, will allow the vehicle to accelerate to a greater vehicle speed than the current set vehicle speed. When the resume/accel switch is released, the PCM will record the vehicle speed and maintain the vehicle speed as the new set vehicle speed. When the Cruise Control System is engaged, momentarily activating the resume/accel switch will allow the vehicle to accelerate at 1.6 km/h (1 mph) increments for each time that the resume/accel switch is momentarily activated, with the maximum acceleration total of 16 km/h (10 mph) over the current set vehicle speed . Momentarily activating the resume/accel switch, after the cruise control system has been disengaged by pressing the brake pedal, will recall the previous set vehicle speed that is recorded in the PCM.

Cruise Control Disengaged

The powertrain control module (PCM) disengages the cruise control operation based on the information received from the throttle actuator control (TAC) module. The TAC module monitors the signal circuits of the following switches:

    * The On/Off switch
    * The TCC/brake switch
    * The stop lamp switch

The TCC brake switch and the stop lamp switch are incorporated into an assembly and are mounted to the brake pedal bracket. Pressing the brake pedal while the cruise control is engaged will disengaged the cruise control system. The TAC module monitors the stop lamp switch signal circuit and the PCM monitors the TCC brake switch/cruise control release signal circuit. When the brake pedal is pressed, the normally closed TCC brake switch opens and the normally open stoplamp switch closes. The TAC module detects a high signal voltage on the stop lamp switch signal circuit and the PCM detects a low signal voltage on the TCC brake switch/cruise control release signal circuit. The TAC module sends a universal asynchronous receiver transmitter (UART) message to the PCM indicating the status of the stop lamp switch. The cruise control system will disengage when the cruise control On/Off switch is turned OFF. The vehicle speed stored in the memory of the PCM will be erased when the cruise control On/Off switch is turned OFF, or the ignition switch is turned OFF.

The cruise control system will disengage when the PCM detects that the driver has the accelerator pedal override active for approximately 60 seconds.

When the cruise control system is disengaged, the PCM sends a class 2 message to the IPC in order to deactivate the cruise control indicator.

Cruise Control Inhibited

The powertrain control module (PCM) inhibits the cruise control operation when any of the following conditions exist:

    * A Cruise Control System related DTC has been set.
    * The vehicle speed is less than 40 km/h (25 mph).
    * The vehicle is in PARK, REVERSE, NEUTRAL, or 1st gear.
    * The engine RPM low.
    * The engine RPM is high.
    * The vehicle speed is too high.
    * The system voltage is not between 6 volts and 16 volts.
    * The Antilock Brake System (ABS)/Traction Control System (TCS) is active for more than 2 seconds.

     
GM Document ID# 879362

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« Last Edit: 02/11/05 10:05 AM by ygmn » Logged

’03  Z71 3:73 LPM Cladded. Fact. Roof Rack, TowPk, XM, Gen 6.2 OnStar, leather & heated/mem. Delphi OEM (UM8 INR Nav System W/Bose Luxury audio). BkUp Cam & entertainment on Nav . DIC, DIO’d Esc. Platinum cluster, Console DVD W/3 Vizlogic 7” 16:9 (two in articultng. '02 HR's & one in pass. visor), 3  A/V inputs/FM headph's. SS893 Fogs, Amber DRL's, All4onHi, All4OnBrake.
sperry
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« Reply #1 on: 12/20/04 08:58 AM »

CC diagrams for 03 & > to date.

« Last Edit: 02/11/05 10:13 AM by ygmn » Logged

’03  Z71 3:73 LPM Cladded. Fact. Roof Rack, TowPk, XM, Gen 6.2 OnStar, leather & heated/mem. Delphi OEM (UM8 INR Nav System W/Bose Luxury audio). BkUp Cam & entertainment on Nav . DIC, DIO’d Esc. Platinum cluster, Console DVD W/3 Vizlogic 7” 16:9 (two in articultng. '02 HR's & one in pass. visor), 3  A/V inputs/FM headph's. SS893 Fogs, Amber DRL's, All4onHi, All4OnBrake.
sperry
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« Reply #2 on: 12/20/04 09:00 AM »

 03:

« Last Edit: 02/11/05 10:13 AM by ygmn » Logged

’03  Z71 3:73 LPM Cladded. Fact. Roof Rack, TowPk, XM, Gen 6.2 OnStar, leather & heated/mem. Delphi OEM (UM8 INR Nav System W/Bose Luxury audio). BkUp Cam & entertainment on Nav . DIC, DIO’d Esc. Platinum cluster, Console DVD W/3 Vizlogic 7” 16:9 (two in articultng. '02 HR's & one in pass. visor), 3  A/V inputs/FM headph's. SS893 Fogs, Amber DRL's, All4onHi, All4OnBrake.
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