What is Caterpillar Fault Code CID4707?

Fault Code CID4707 indicates a Controller Area Network (CAN) communication error between the Engine Control Module (ECM) and another electronic control unit on the machine. This diagnostic trouble code specifically signals that the ECM has detected a loss of communication or abnormal message transmission on the CAN data link, which serves as the digital nervous system connecting all electronic controllers on Caterpillar excavators.

The CAN Bus system is critical for coordinating functions between the engine, hydraulic system, display monitor, and other electronic modules. When CID4707 appears, it means the ECM cannot properly communicate with at least one controller, potentially affecting machine performance, monitoring capabilities, and diagnostic functions. For used excavators, this code often points to wiring degradation or connector issues that develop over thousands of operating hours.

Common Symptoms

• Warning lights illuminated on the instrument cluster, often accompanied by a check engine light or communication error icon
• Loss of certain display functions on the monitor, including missing engine parameters, hydraulic temperatures, or system status information
• Intermittent derate conditions where engine power is reduced as a protective measure due to incomplete system data
• Erratic gauge behavior with readings dropping out or showing implausible values sporadically
• Inability to access full diagnostic information through service tools or onboard displays

Potential Causes

Damaged or corroded CAN Bus wiring harness is the most common culprit in used machines, particularly at harness routing points near the swing bearing or along the boom where flexing occurs. Connector corrosion at controller junction points allows moisture intrusion that degrades electrical contacts over time.

Failed terminating resistors on the CAN network can cause signal reflection and communication errors. ECM or secondary controller failures occasionally occur, though less frequently than wiring issues. Aftermarket accessory installations may have improperly tapped into the CAN network, creating signal interference. Battery voltage fluctuations or poor grounding can disrupt digital communications on older machines with aging electrical systems.

How to Troubleshoot and Fix Code CID4707

Step 1: Visual Harness Inspection Begin by thoroughly inspecting all CAN Bus wiring (typically twisted-pair yellow and green wires on Caterpillar machines) from the ECM throughout the machine. Focus on known wear points: where harnesses pass through the swing bearing, along the boom, and near the hydraulic pump. Look for chafed insulation, pinched wires, or corroded connectors. On used excavators, harness damage from rubbing is extremely common.

Step 2: Connector and Terminating Resistor Check Disconnect and inspect all CAN network connectors for corrosion, bent pins, or moisture contamination. Clean contacts with electrical contact cleaner and apply dielectric grease. Using a multimeter, verify terminating resistor values at network endpoints (should measure approximately 60 ohms across CAN High and CAN Low when controllers are disconnected).

Step 3: Electronic Diagnostic Testing Connect Caterpillar Electronic Technician (Cat ET) or equivalent diagnostic software to identify which specific controller has lost communication. Monitor live CAN Bus traffic to determine if the fault is intermittent. Check battery voltage (should be 12-14V) and verify all ground connections are clean and tight, as poor grounds frequently cause communication errors in older machines.

Step 4: Controlled Component Testing If wiring and connectors pass inspection, perform isolation testing by disconnecting secondary controllers one at a time to identify if a failed module is pulling down the entire network. Replace or repair identified faulty components.

Disclaimer: CAN Bus diagnostics require specialized knowledge and tools. If troubleshooting does not resolve CID4707, consult a certified Caterpillar technician or qualified heavy equipment diagnostic specialist to prevent misdiagnosis and unnecessary parts replacement.