DTC U0402-68: Signal Error From TCM: Notes

WARNING: This page is about a different car, the 2016 Mazda CX-3. However, it is still accessible from the selected car via links, so may be relevant.

DTC U0402:68	Signal error from TCM
DETECTION CONDITION	The instrument cluster received error signals from the transaxle for 1 s or more with the ignition switched ON (engine off or on).
FAIL-SAFE FUNCTION	Refer to "FAIL-SAFE FUNCTION TABLE ". (Refer to DTC TABLE [AWD CONTROL MODULE] .)
POSSIBLE CAUSE	The transaxle could not send a normal signal temporarily. (DTCs are stored in the TCM.) TCM malfunction Instrument cluster malfunction
SYSTEM WIRING DIAGRAM	-