Theory Of Operation
WARNING: This page is about a different car, the 2017 Jeep Cherokee. However, it is still accessible from the selected car via links, so may be relevant.
The purpose of the diagnostic is to detect circuit failures on any of the output stages. All output stages are controlled by a current controller that the Transmission Control Module (TCM) can operate in two different modes:
- Current controlled mode (pressure regulators)
- Switched mode or Pulse Width Modulated (PWM) controlled (solenoids)
Solenoid Monitoring: The TCM measures the actual solenoid voltages and compares them to calibrated thresholds to identify the following electrical failures:
- Short to ground or open circuit
- Short to battery