GM Service Manual Online
For 1990-2009 cars only

Ignition positive voltage is supplied from the 10 Amp CRUISE fuse, to the cruise control module. The cruise control module is grounded to the chassis. When the cruise control switch is on, ignition positive voltage is supplied to the cruise on/off terminal of the cruise control module. When the driver presses the normally closed cancel switch, the cruise control cancel signal circuit opens. The BCM then sends a class 2 message to the PCM to inhibit cruise control operation. The vehicle speed stored in the memory of the cruise module will be lost. If the brake pedal is not pressed, ignition positive voltage is supplied through the cruise control brake switch, to the brake input 1terminal of the cruise control module. If the brake pedal is pressed, battery positive voltage is supplied from the 20 Amp STOP LPS fuse, through the closed stop lamp switch to the brake input 2 terminal of the cruise control module. When depressing resume/accelerate (R/A) on the steering wheel control switch, ignition positive voltage is applied to the resume/accelerate terminal of the cruise control module. When the Set/Coast is pressed on the steering wheel control switch, ignition positive voltage is applied to the set/coast terminal of the cruise control module.

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

The PCM will inhibit cruise control:

    • When vehicle speed is less than 25 mph (40 km/h).
    • When PARK, REVERSE, NEUTRAL, or 1st gear is indicated by the transaxle range switch.
    • With low engine RPM.
    • With high engine RPM (fuel cut-off).
    • When vehicle speed is too high.
    • When an over or undercharged 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 requests that the cruise control module disengage cruise control. The PCM accomplishes this request by opening the cruise inhibit output circuit. If the cruise engage output signal, sent by the cruise control module to the PCM, indicates that the cruise control is still engaged after the PCM has requested that cruise control disengage, the PCM sets a DTC.