Transmission Control Module

The Transmission Control Module (TCM) performs four self-test integrity diagnostics on its internal hardware and software to check for faults. A fault is detected if:

1. The diagnostic drive cycle is active and an electrical fault of the ground return line has been detected.
2. The engine speed is greater than 420 RPM, the diagnostic drive cycle is active and the supply voltage is greater than 18 volts or less than 8 volts.
3. The calculated checksum does not match the stored checksum.
4. The diagnostic drive cycle is active and the incorrect calibration file has been selected.

If the table does not include details of the following enabling conditions: intake air and engine coolant temperature, vehicle speed range, and time after engine start-up then the state of these parameters has no influence upon the execution of the monitor. See Fig 1 .

Fig 1: Transmission Control Module Fault Enabling Conditions

Courtesy of LAND ROVER NORTH AMERICA, INC.