Postby smj999smj » Wed Jan 18, 2017 9:19 pm
There is obviously a communication problem in the Controlled Area Network (CAN). CAN is a way of multiple control units to communicate with each other via a pair of twisted wires between them. In other words, the ECM,ABS control unit, TCM, cluster, 4WD control unit, BCM, etc., all "talk to" each other. Sometimes this issues can be caused by a poor battery connection or charging system issue, which is easy enough to check. However, if it is more than that, it will require a capable scan tool and an auto technician who has experience in CAN system problems. The best place would likely be a Nissan dealer.
To break down the codes, the U1000 is a general code for a CAN communication problem. The P1212 is an ABS/TCS communication problem, which could be caused by a weak battery, a bad ABS actuator/control unit assembly, or a shorted or open circuit or bad connection in the ABS actuator/control unit circuit. It is triggered when the ECM is not receiving continuous information from the ABS system. The P1721 is for a problem with the vehicle speed sensor monitor in which the TCM does not get a proper signal from the cluster via CAN communication. This can be caused by the speed sensor circuit being shorted or open.