4.1 Control Module Malfunctions: Notes

The TCM performs several 'self check' procedures to ensure correct operation. It is possible due to the nature of these faults that the module will fail to communicate with other nodes. However, condemnation of the TCM should not take place until any CAN or power supply related problems have been resolved.

There are three self check procedures for the TCM.

• Check on ROM by calculating a checksum and comparing this with a known stored value.
• Check on non-volatile diagnostic memory by writing a test pattern and then reading it back.
• Internal 'watchdog' hardware to check whether the TCM has crashed.