P1921
Symptom: CHECK GEARBOX warning lamp is on. TCM in Limp-Home mode.
P1921 |
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