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P1921

Symptom: CHECK GEARBOX warning lamp is on. TCM in Limp-Home mode.

P1921

No bus data from ECM.


Fault symptoms

CHECK GEARBOX warning lamp is on.

TCM in Limp-Home mode.

Conditions

The TCM has had contact with the ECM at some time during the same ignition-on period

Fault criteria

If there has not been communication on the bus between the ECM and the TCM for more than 4 s a P1921 diagnostic trouble code is generated

Diagnostic help

See bus and diagnostic fault finding