Theory Of Operation

This diagnostic checks for the electrical faults of the sensor power supplies, sensor module or the connecting wiring. These electrical faults may include short to battery, short to ground and open circuit. There are three different sensor power supplies, named VS1, VS2 and VS3 which are provided by an integrated circuit internal to the Transmission Control Module (TCM). The 1st-3rd actuator position sensor, the 5th-RV actuator position sensor and the odd clutch position sensor are supplied by VS1. The even clutch pressure sensor, the 2nd-4th actuator position sensor, the 6th actuator position sensor and the gate select position sensor are supplied by VS2. The hydraulic pressure sensor, the odd and even clutch speed sensors and the park position sensor are supplied by VS3. A self diagnostic is performed by the integrated circuit on each power supply. The diagnostic continuously checks the result of the internal integrated circuit test by reading an internal register via SPI communication interface. If it indicates an electrical fault on at least one of the three supplies, then the diagnostic will set a fault in the TCM.