Theory Of Operation

The purpose of the diagnostic is to check if the Analog to Digital Converter (ADC), which is included as part of the microcontroller in the Transmission Control Module (TCM), is functioning properly. The monitoring consists of the following three separate checks:

1. Sampling check: 

   The Random Access Memory (RAM) area used by the ADC is checked to determine if samples have been stored, overwriting the known data stored during TCM initialization.

2. Out of range check: 

   The sampled voltages in the ADC are checked to be within a valid operating range.

3. Rationality check: 

   The microcontroller generates multiple control voltages, which are sampled by the ADC. The sampled voltages are compared to the control voltages.