What is Caterpillar Fault Code EID1660?

Fault Code EID1660 indicates an Abnormal Update Rate for the Electronic Control Module (ECM) or a communication timing issue within the CAN (Controller Area Network) bus system. This diagnostic trouble code specifically signals that the engine ECM is not receiving data updates from connected modules at the expected frequency, or that message transmission intervals have deviated from manufacturer specifications.

This code affects Caterpillar excavators equipped with ACERT or C-Series engines using advanced electronic communication networks. The CAN bus system coordinates critical data exchange between the engine ECM, hydraulic controller, display module, and other electronic components. When update rates fall outside acceptable parameters, the machine's ability to synchronize engine performance with hydraulic demand becomes compromised, potentially leading to reduced operational efficiency and protective derate modes.

Common Symptoms

• Warning lights illuminated on the instrument cluster, particularly the malfunction indicator lamp (MIL) or diagnostic lamp
• Intermittent communication errors displayed on the monitor panel, showing temporary loss of engine data
• Erratic engine response to throttle inputs or inconsistent power delivery during operation
• Reduced engine power (derate mode) as the ECM enters a protective state due to unreliable data
• Hydraulic system delays or uncoordinated responses when multiple functions are operated simultaneously

Potential Causes

The most common technical causes for EID1660 in used Caterpillar excavators include:

• CAN bus wiring harness damage from abrasion, particularly at known rub points near the swing bearing or along the boom where cables flex repeatedly
• Corroded or loose connector pins at the ECM, display module, or junction blocks—especially prevalent in machines operating in wet or corrosive environments
• Failing ECM internal circuitry due to age, voltage spikes, or moisture intrusion in older units
• Incompatible software versions between modules after previous repairs or component replacements without proper recalibration
• Defective terminating resistors at CAN bus network endpoints causing signal reflection issues
• Aftermarket component interference from non-OEM accessories improperly integrated into the electrical system

How to Troubleshoot and Fix Code EID1660

Step 1: Connect Diagnostic Software Use Caterpillar Electronic Technician (Cat ET) to retrieve active and logged codes. Check the event timestamp data to determine if the fault is continuous or intermittent. Review all module communication status—identify which specific module shows abnormal update rates.

Step 2: Perform Visual Harness Inspection On used excavators, physically inspect the CAN bus wiring harness from the ECM to all connected modules. Pay special attention to harness routing near the swing bearing, cab floor penetrations, and boom pivot points where vibration and movement cause wire chafing. Look for exposed wires, damaged insulation, or previous repair attempts with electrical tape.

Step 3: Test Connector Integrity Disconnect and inspect all CAN bus connectors for corrosion, bent pins, or moisture. Clean contacts with electrical contact cleaner and apply dielectric grease during reassembly. Check connector locking mechanisms—loose connections create intermittent resistance.

Step 4: Measure CAN Bus Resistance Using a digital multimeter, measure resistance across the CAN-High and CAN-Low wires at the ECM connector with all modules disconnected. Proper terminating resistance should read approximately 60 ohms (two 120-ohm resistors in parallel). Readings significantly higher indicate open circuits or missing terminators; lower readings suggest short circuits.

Step 5: Verify Module Software Compatibility Through Cat ET, confirm all module software versions are compatible. Mismatched firmware between the engine ECM and hydraulic controller commonly causes timing conflicts in used machines with mixed replacement parts.

Step 6: Isolate Faulty Module Systematically disconnect non-essential modules from the CAN network while monitoring for code clearance. If EID1660 disappears when a specific module is disconnected, that component likely has internal faults affecting bus communication.

For used excavators specifically: Before replacing expensive modules, always address environmental damage first. Corrosion and harness wear account for over 70% of communication faults in machines with 5,000+ operating hours.

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Disclaimer: This guide provides general diagnostic information. Complex electrical issues may require factory-trained technicians with specialized Caterpillar diagnostic equipment. Always consult the machine's service manual and consider professional assistance for repairs involving ECM replacement or software recalibration.