Engine Speed

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The TCM control module receives information on the current engine speed, unit rpm, via the bus. It compares the engine speed with the speed of the input shaft when Lock-up is activated. Deviations greater than 100 rpm between the engine speed and it speed of the input shaft will cause diagnostic trouble code P0741 to be generated.

Diagnostics
A malfunction will generate a diagnostic trouble code primarily in Trionic.

When bus communication with Trionic ceases, diagnostic trouble code P1921 will be generated and the transmission goes into Limp-home mode.

Inaccurate information on the bus causes diagnostic trouble code P1971 to be generated. Depending on the fault, the TCM may activate the emergency operation program (Limp-Home mode).