What is Caterpillar Fault Code CID2670?

Caterpillar Fault Code CID2670 indicates an abnormal update rate or communication issue with the Machine Security System (MSS) on the Controller Area Network (CAN) datalink. This diagnostic trouble code triggers when the Electronic Control Module (ECM) detects that security system messages are not being transmitted at the expected frequency or are missing entirely from the CAN bus communication network.

This fault is critical because the Machine Security System verifies operator authorization and communicates equipment status across multiple control modules. When CID2670 activates, the excavator's security protocols may prevent normal operation or limit machine functionality to protect against unauthorized use. On Caterpillar excavators, this communication breakdown can affect engine starting procedures, keyless start systems, and integration with Product Link telematics systems.

Common Symptoms

• Engine cranks but fails to start or requires multiple key cycles before successful ignition
• Security system warning light illuminated on the instrument cluster or monitor display
• Intermittent starting issues, particularly after the machine has been sitting idle or in cold weather conditions
• Error messages on the digital display referencing security system or authorization failures
• Machine may start normally but log the fault code, causing concern during pre-sale inspections of used equipment

Potential Causes

The most common technical causes for CID2670 on used Caterpillar excavators include:

• Corroded or loose connections at the Machine Security Module (MSM) or its wiring harness, especially common in high-hour machines exposed to moisture
• Damaged CAN bus wiring due to chafing against frame components or pinching near the operator cab mounting points
• Failing Machine Security Module itself, particularly in excavators with 8,000+ operating hours
• Low battery voltage or poor ground connections affecting communication signal integrity across the network
• ECM software version mismatch after component replacements or incomplete software updates
• Aftermarket key or security system components that don't communicate properly with OEM protocols

How to Troubleshoot and Fix Code CID2670

Step 1: Perform Initial System Checks Connect Caterpillar Electronic Technician (Cat ET) diagnostic software to retrieve active and logged fault codes. Document all codes and their occurrence frequency. Check battery voltage—ensure it's above 12.5V at rest and 13.5-14.5V while running, as low voltage commonly causes CAN communication errors.

Step 2: Inspect Physical Connections and Wiring Locate the Machine Security Module (typically mounted near the operator station or behind the instrument panel). Inspect all harness connectors for corrosion, bent pins, or moisture intrusion—this is especially critical on used excavators. Check CAN bus wiring (typically twisted orange and yellow wires) for damage, particularly where harnesses route near moving components or through bulkhead connectors.

Step 3: Test Communication and Module Function Using Cat ET software, monitor real-time CAN bus traffic and verify the MSM update rate. Normal communication occurs at specific intervals (consult service manual for exact specifications). If communication is absent or erratic, perform a resistance check on CAN bus termination—should read approximately 60 ohms across the network. For used machines, clean all connector pins with electrical contact cleaner and apply dielectric grease before reconnecting.

Step 4: Component Testing and Replacement If wiring and connections test good, the Machine Security Module itself may require replacement. Before ordering parts for used excavators, verify the ECM software version is current and compatible with installed security hardware. Flash ECM to latest software version if needed, then clear codes and test operation.

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Disclaimer: This guide provides general troubleshooting information. 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 training and equipment.