What is Caterpillar Fault Code CID1698?

Caterpillar fault code CID1698 indicates a communication error or data link failure within the machine's CAN (Controller Area Network) system, specifically related to a missing or intermittent message from a connected electronic control module. This diagnostic trouble code (DTC) triggers when the primary ECM (Engine Control Module) fails to receive expected data packets from another controller on the network within a specified timeframe.

In Caterpillar excavators, the CAN bus network connects multiple electronic modules including the engine controller, hydraulic controller, display monitor, and various sensor modules. When CID1698 appears, it signals that critical communication between these systems has been interrupted, potentially affecting machine diagnostics, performance monitoring, and integrated system functions. This is particularly problematic in modern excavators where coordinated control between engine power and hydraulic demand is essential for optimal fuel efficiency and performance.

Common Symptoms

• Warning lights illuminated on the operator display, often accompanied by a "Check Engine" or communication error message
• Intermittent loss of display information, including gauge readings, hour meter, or system status indicators
• Reduced machine performance or derate mode activation as the ECM enters a protective state due to missing data
• Inability to access full diagnostic information through Cat Electronic Technician (ET) software
• Erratic behavior of integrated systems such as auto-idle, power modes, or hydraulic response characteristics

Potential Causes

The most common technical causes for CID1698 on used Caterpillar excavators include:

• Corroded or damaged CAN bus connectors, especially at harness junction points exposed to moisture or debris
• Worn or frayed wiring harnesses at known rub points near the swing bearing, boom cylinders, or cab mounting areas
• Failed terminating resistor on the CAN network (typically 120-ohm resistance required at each network end)
• Faulty electronic control module (display monitor, implement controller, or secondary ECM) no longer transmitting properly
• Voltage irregularities in the machine's electrical system causing intermittent module resets or communication dropouts
• Corroded ground connections affecting network signal integrity, common in machines operating in wet or marine environments

How to Troubleshoot and Fix Code CID1698

Step 1: Initial Diagnostic Scan Connect Cat Electronic Technician (ET) software to identify which specific module is reporting the missing message. Review active and logged codes to determine if multiple communication faults exist, which may indicate a network-wide issue rather than a single module failure.

Step 2: Physical Harness Inspection On used excavators, physically inspect all CAN bus harness connectors along the network path. Pay particular attention to connectors in the swing post area, behind the operator display, and near hydraulic valve banks. Look for:

• Green corrosion on connector pins (indicates moisture intrusion)
• Bent or pushed-back pins causing intermittent contact
• Harness wear at movement points or cable ties that are too tight

Step 3: Electrical Testing Using a digital multimeter, verify CAN bus signal integrity:

• Measure resistance between CAN High and CAN Low terminals with all modules connected (should read approximately 60 ohms with proper terminating resistors)
• Check for voltage presence on CAN lines (typically 2.5V baseline with 1-2V differential during communication)
• Verify ground continuity at each module with less than 0.5-ohm resistance to chassis ground

Step 4: Module Isolation Systematically disconnect non-critical modules one at a time to isolate a faulty controller that may be pulling down the network. After each disconnection, clear codes and monitor for recurrence during operation.

Step 5: Terminating Resistor Verification Check that proper 120-ohm terminating resistors exist at both ends of the CAN network. In used machines, these resistors can fail or be accidentally removed during previous repairs.

For used excavators specifically, always clean and apply dielectric grease to all connectors during reassembly to prevent future corrosion-related communication failures.

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Disclaimer: This guide provides general troubleshooting information for Caterpillar CID1698. Always consult the official Caterpillar service manual for your specific machine model and serial number. Complex electrical diagnostics should be performed by qualified technicians with proper diagnostic equipment. Improper repairs to CAN bus systems can cause additional module damage.