The 4WD ECU gets some data from ECU and TCU through CAN line communication. And it controls 4WD coupling according to each vehicle's status.
If the relative data in the ECU and ABS(ESP) module doesn't correspond with the data in the 4WD ECU, the 4WD ECU sets P1837 and lets a warning lamp turn on.
Item
Detecting Condition
Possible cause
DTC Strategy
Checking ECU and ABS(ESP)'s CAN signal
Open or short in the CAN communication line
An error in the ECU, ABS(ESP)
Enable conditions
IG " ON "
Threshold value
The 4WD ECU can't senses its vehicle status
Detecting time
2 seconds