What is Caterpillar Fault Code CID672?

Caterpillar Fault Code CID672 indicates a communication error or data link failure within the machine's Controller Area Network (CAN) system, specifically related to a missing or intermittent message from a critical electronic control module. This code appears when the primary Electronic Control Module (ECM) fails to receive expected communication signals from connected components within the prescribed time interval.

CID672 is part of Caterpillar's standardized Component Identifier (CID) diagnostic system used across their construction equipment lineup. The CAN bus serves as the nervous system of modern excavators, enabling constant communication between the engine controller, hydraulic systems, display monitors, and various sensors. When this communication breaks down, the machine may enter protective modes or experience operational limitations. For used excavators, this code often signals degraded wiring harnesses, corroded connectors, or aging control modules that have accumulated years of vibration and environmental exposure.

Common Symptoms

• Warning lights illuminated on the operator display panel, often with reduced engine power messages
• Machine enters derate mode, limiting engine RPM or hydraulic functions to protect systems
• Intermittent loss of gauge functionality, including fuel level, temperature, or hour meter readings
• Erratic operation of specific functions like swing, boom, or auxiliary hydraulics
• Engine may start normally but display communication errors during operation or refuse to start entirely

Potential Causes

The most frequent causes of CID672 in used Caterpillar excavators include:

• Corroded or loose CAN bus connectors, particularly at bulkhead pass-throughs and module connection points
• Damaged wiring harnesses from rubbing against frame components, especially near articulation points and behind the operator cab
• Failed electronic control modules (ECM, display controller, or transmission controller) due to moisture intrusion or component age
• Poor ground connections at chassis grounding points, which degrade over time from corrosion
• Voltage supply issues from weak batteries, failing alternators, or corroded battery terminals affecting module power
• Aftermarket component interference from improperly installed accessories disrupting CAN communication

How to Troubleshoot and Fix Code CID672

Step 1: Visual Inspection Begin with a thorough physical examination of all wiring harnesses along the main chassis, paying special attention to areas where cables route near moving parts or sharp edges. Check every CAN bus connector for corrosion, bent pins, or moisture intrusion. On used machines, inspect harness protective looms for cracking or wear that exposes wires.

Step 2: Electrical Testing Using a digital multimeter, verify proper voltage at all control modules (typically 12-24V depending on machine specifications). Check CAN High and CAN Low signal wires for proper resistance (typically 60 ohms across the network with all modules connected). Use Caterpillar Electronic Technician (Cat ET) diagnostic software to identify which specific module is failing to communicate.

Step 3: Component Testing and Repair Isolate the problematic circuit by disconnecting modules one at a time while monitoring for code clearance. Clean all connector terminals with electrical contact cleaner and apply dielectric grease. For used excavators, replace any harness sections showing wear before condemning expensive modules. Verify all chassis ground points are clean and tight, re-establishing grounds as needed.

Step 4: Module Replacement If communication remains absent after harness and connector repair, replace the non-communicating control module. Always verify software compatibility and perform parameter programming using Cat ET after module replacement.

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Disclaimer: This guide provides general troubleshooting information for experienced technicians. Always consult official Caterpillar service documentation and consider professional diagnostic assistance for complex electrical issues. Improper repairs may cause additional system damage or safety hazards.