What is Caterpillar Fault Code CID670?

Caterpillar fault code CID670 indicates an abnormal update rate from the Chassis Controller (CCM) on the CAN (Controller Area Network) data link. This code triggers when the Engine Control Module (ECM) or other machine controllers fail to receive timely communication signals from the Chassis Controller at the expected frequency.

The Chassis Controller manages critical machine functions including implement control, hydraulic systems, and operator interface communications. When CID670 appears, it signals a breakdown in the CAN bus communication network, which serves as the nervous system for your Caterpillar excavator. This fault compromises the machine's ability to coordinate functions between multiple electronic control modules, potentially affecting operational safety and performance. For used excavators, this code often indicates aging electrical infrastructure or accumulated environmental damage to communication networks.

Common Symptoms

• Warning lights illuminated on the operator display, often accompanied by specific CAN communication error messages
• Intermittent or complete loss of implement control functions, including boom, stick, or bucket responsiveness
• Erratic gauge readings or complete failure of the instrument cluster display
• Derated engine performance or unexpected machine shutdown as a protective measure
• Hydraulic system irregularities such as sluggish response or unpredictable actuator movement

Potential Causes

The most common technical causes for CID670 in used Caterpillar excavators include:

• Damaged or corroded CAN bus wiring harness, particularly at known rub points near the swing bearing, boom pivot, or undercarriage routing areas
• Failed Chassis Controller (CCM) due to moisture intrusion, vibration damage, or component age degradation
• Loose or corroded connector terminals on CAN communication circuits, especially the 120-ohm terminating resistors
• Voltage supply issues to the CCM caused by faulty power distribution modules or ground circuit failures
• ECM software version incompatibility or corrupted calibration files, particularly on machines with previous controller replacements
• Electromagnetic interference (EMI) from aftermarket accessories or damaged shielding on CAN twisted-pair wiring

How to Troubleshoot and Fix Code CID670

Step 1: Perform Initial Diagnostic Scan Connect Caterpillar Electronic Technician (Cat ET) diagnostic software to verify CID670 and check for additional active or logged codes. Document all fault codes, timestamps, and occurrence frequency. Check the software version of both the ECM and CCM to ensure compatibility.

Step 2: Inspect CAN Bus Physical Infrastructure Thoroughly examine the CAN bus wiring harness from the CCM to all connected modules. On used excavators, pay special attention to harness routing through articulation points where cable flexing causes insulation breakdown. Check for pinched wires, abraded insulation, or evidence of previous repairs. Inspect all connector pins for corrosion, bent terminals, or moisture contamination—clean with electrical contact cleaner if necessary.

Step 3: Test CAN Network Integrity Using a digital multimeter, measure CAN bus terminating resistance between CAN High and CAN Low circuits with the key off—you should read approximately 60 ohms (two 120-ohm resistors in parallel). Disconnect the CCM connector and measure supply voltage (should be 8-14V with key on) and verify solid ground circuits (less than 0.1 ohms resistance to battery negative).

Step 4: Monitor Live Communication Data With Cat ET connected, monitor real-time CAN message traffic and specifically watch the CCM update rate. If communication is intermittent, perform a wiggle test on harnesses and connectors while monitoring—this often reveals mechanically-induced connection failures common in older machines.

Step 5: Component Replacement Verification If diagnostics point to CCM failure, ensure replacement controllers are properly configured and programmed before installation. After any repairs, clear fault codes, perform a CAN network reset, and conduct a thorough operational test of all machine functions.

For used excavators specifically: Before replacing expensive controllers, invest time inspecting harness conditions and connector integrity—corrosion and physical damage account for over 70% of CAN communication faults in aging equipment.

---

Disclaimer: This guide provides general troubleshooting information. Complex electrical diagnostics should be performed by qualified Caterpillar technicians with appropriate diagnostic equipment. Always consult official Caterpillar service documentation for your specific machine model and serial number.