U2023-malfunction received from external node- how do we fix this problem

Taking it to a qualified repair shop would be your best bet .
U2023 External Node Fault DTC ABS Module REFER to Section 418-00 . U2023 Fault Received From External Node SJB REFER to Section 418-00 .
Which module did you pull this code from ? What type scanner or was it a code reader ?
Do you know what a serial data network is ? specifically C.A.N - controller area network ! Do you know what a node is ? A control module ,PCM ,SJB ,IPC etc...
Communications Network Smart Junction Box (SJB) The SJB is connected to the medium speed controller area network (CAN) communications bus. If one of the bus wires becomes shorted to ground or voltage, communications can continue at a reduced level. Check circuits 1847 (WH/OG), and 1848 (PK/OG) between the SJB C2280a, the instrument cluster C220 and the data link connector (DLC) C251. Total resistance values must not be more than 5 ohms. If the resistance is more than 5 ohms, there is an open circuit in the medium speed CAN, damage to the DLC C251, or damage to the SJB C2280a. Since both the SJB and the instrument cluster share network termination responsibilities, a problem in either of these modules can result in a medium speed CAN failure. For additional SJB information, refer to Section 419-10 .
Powertrain Control Module (PCM) The PCM is on the high speed CAN. The PCM controls the engine for better fuel economy, emissions control, failure mode detection and storage, and all passive anti-theft system (PATS) functions. If one of the bus wires becomes shorted to ground or voltage, communications can continue at a reduced level. Check the high speed CAN circuits 1908 (WH) and 1909 (BK), between the PCM C175b and the DLC C251. Total resistance values must not be more than 5 ohms. If the resistance is more than 5 ohms, there is an open circuit in the high speed CAN, damage to the DLC C251, damage to the PCM C175b, or a problem in the in-line connector. Since both the PCM and the instrument cluster share network termination responsibilities, a problem in either of these modules can result in a high speed CAN failure. For additional PATS information, refer to Section 419-01B . For additional PCM information, refer to the Powertrain Control/Emissions Diagnosis (PC/ED) manual. For removal and installation information, refer to Section 303-14A or Section 303-14B .
Instrument Cluster The instrument cluster is on the high speed CAN. It is an analog face cluster with a digital odometer. The instrument cluster displays a variety of information. If one of the bus wires becomes shorted to ground or voltage, communications can continue at a reduced level. Check the high speed CAN circuits 1908 (WH) and 1909 (BK) between the instrument cluster C220 and the DLC C251. Total resistance values must not be more than 5 ohms. If the resistance is more than 5 ohms, there is an open circuit in the CAN network, damage to the DLC C251, damage to the instrument cluster C220, or a problem in the in-line connector. Since both the PCM and the instrument cluster share network termination responsibilities, a problem in either of these modules can result in a high speed CAN failure. For additional instrument cluster information, refer to Section 413-01 .
The vehicle has 3 module communication networks: high speed and medium speed CAN network, which are comprised of unshielded twisted pair cable, and the international standards organization (ISO) 9141 communication network, which is a single wire network. All 3 networks are connected to the data link connector (DLC). This makes diagnosis and testing of these systems easier by allowing a diagnostic tester to be able to diagnose and control any module on the 3 networks from the connector. The DLC can be found under the instrument panel between the steering column and the radio.