Cruise Control Description And Operation
The cruise control system is an integration of the cruise control switches, brake switches and ECM. Cruise control inputs from the cruise brake switch, cruise on/off switch, cruise resume/accel switch, cruise set/coast switch and stop lamp switch go directly to the ECM. The following list is the criteria that the ECM must detect before it will control vehicle speed:
- Must have ignition voltage at the cruise on/off switch input.
- Must have ignition voltage at the cruise brake switch input.
- Must have zero volts at the stop lamp switch input.
- Must have a valid vehicle speed signal from the TCM over the CAN link at or over 39 km/h (24 mph).
- No DTCs must be present that would interfere with the ability to control the throttle plate correctly or would interfere with the ability of the driver to disengage the cruise control under any circumstance. These would include: Any APP sensor, brake switch, serial data communication, ECT sensor, system voltage, TP sensor, throttle actuator, transaxle range switch or vehicle speed circuit.
- Must have detected a set/coast switch transition from zero volts to ignition voltage and back to zero volts within 0.06 - 1.4 seconds when all conditions to enable cruise have been met.
Once the ECM receives the correct voltage levels at the various inputs and the other criteria has been met, it will engage cruise control. The ECM will not disengage cruise control unless:
- A brake transition is detected
- Transmission is placed in a non-cruise gear (P, R or N)
- Vehicle speed drops below 32 km/h (20 mph)
- Vehicle speed exceeds 161 km/h (100 mph)
- Vehicle is accelerating or decelerating too quickly
- Traction control is active
- Engine coolant temperature is too high
- Any of the DTCs mentioned above have set or a fault is detected in any of those circuits