Method for controlling the internal electronic range selection for a 9 speed automatic transmission

A method for controlling internal electronic range selection for an automatic transmission, comprising:

• confirming if a range change command has been ordered from a current transmission operating state;
• verifying expected performance from at least first and second mode valves and a park servo are present in the current transmission operating state prior to allowing a range change event;
• during the range change event:
• generating proactive commands including ordering a reduction in a hydraulic system pressure;
• and
• identifying if an unexpected event is detected;
• and
• following completion of the range change event confirming expected performance is obtained from at least the first and second mode valves and the park servo to achieve a driver intended state.

A method for controlling internal electronic range selection for an automatic transmission, comprising:

• confirming if a range change command has been ordered from a current transmission operating state;
• monitoring in parallel multiple system components including at least first and second mode valves and a park servo;
• and
• providing four-layers of proactive safety software for operation and feedback of an electronic range selection (ETRS) system, including:
• in a first layer, verifying the at least first and second mode valves and the park servo are fully stroked in the current transmission operating state prior to allowing a range change event;
• in a second layer and during the range change event generating proactive commands including temporarily ordering a reduction in a hydraulic system pressure to approximately 200 kPa;
• in a third layer, identifying if an unexpected event including a failure of any one of the at least first and second mode valves and the park servo to be fully stroked is detected;
• and
• in a fourth layer, following completion of the range change event confirming an expected performance is obtained from all of the multiple system components.