CAN BUS Diagnostic and Testing Guide – Electronic Service Tool (EST) for CASE Tier IV Equipment

This manual explains the Controller Area Network (CAN-BUS) diagnostic principles used in CASE M-Series Dozers and other CNH Tier IV machines.
It introduces controller networking, voltage logic, and EST-based troubleshooting for CAN BUS 1 & 2 systems linking the ECM, UCM, AIC, Denox Module, and Telematics controllers.

Key learning points:

• CAN BUS architecture: layout, twisted-pair topology, termination resistors (120 Ω), and node addressing.

• Signal logic: CAN Hi (2.5–3.5 V DC) and CAN Lo (1.5–2.5 V DC).

• EST testing procedures: voltage and resistance diagnosis, controller status interpretation, and fault isolation.

• M-Series Dozer application: dedicated diagrams on pages 10–11 illustrate small and large dozer CAN BUS maps with diagnostic port placement.

Coverage

• Introduction to CAN Technology

  • Origin (Bosch & Intel 1984)

  • Use in Automotive and Industrial applications

• Purpose of CAN Systems

  • Replacing mechanical components with electronic modules

  • Networked communication for shared signals

• Benefits of CAN

  • Reduced wiring and connectors

  • Improved diagnostics and sensor sharing

  • Enhanced reliability and signal accuracy

• Terminology

  • ECU, EMC, BUS, CAN Hi/Lo voltage ranges, Terminator resistors

• CAN Circuit Construction

  • Twisted pair wiring and magnetic field cancellation

  • Shielded vs unshielded configurations

• Overview of CAN System

  • Digital message exchange between processors (page 5)

  • External and internal terminators illustration

• Testing Procedures with EST and DVOM

  • Voltage test for good circuit (2.5–3.5 V range)

  • Offline controller diagnosis (shorted BUS)

  • Resistance test for termination integrity (60–30 Ω)

  • Short and open circuit fault examples

• Troubleshooting Guide

  • Step-by-step fault isolation via controller disconnects

  • Interpretation of “ONLINE/OFFLINE” status on EST

• M-Series Dozer CAN BUS Layouts

  • Small Dozer Network (UCM, AIC, Telematics, ECM)

  • Large Dozer Network with Denox Module and NOx sensor integration

Delivery

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