What is Caterpillar Fault Code CID568?

CID568 indicates a communication error or malfunction within the Caterpillar machine's CAN (Controller Area Network) data link system, specifically related to a missing or intermittent message from a critical electronic control module. This fault code typically appears when the Electronic Control Module (ECM) fails to receive expected data packets from another controller on the network, such as the hydraulic control module, display monitor, or transmission controller.

This communication failure is critical because modern Caterpillar excavators rely on continuous data exchange between multiple control systems to optimize performance, fuel efficiency, and safety protocols. When CID568 is active, the machine may enter derate mode or limit certain functions to protect components from operating without proper sensor feedback or control coordination.

Common Symptoms

• Warning light illumination on the instrument cluster, often accompanied by a specific CAN communication fault message on the display
• Reduced engine power or derate mode activation, limiting the machine to low-idle or restricted RPM ranges
• Intermittent loss of gauge functionality, including fuel level, temperature readings, or hour meter displays
• Hydraulic system limitations or unresponsive auxiliary functions due to communication loss with hydraulic controllers
• Erratic machine behavior such as unexpected shutdowns, delayed throttle response, or transmission shift issues

Potential Causes

• Damaged or corroded CAN bus wiring harness, particularly at known rub points near the swing bearing, boom cylinder routing, or undercarriage
• Loose or corroded electrical connectors at control modules, especially on used machines exposed to moisture or debris intrusion
• Failed electronic control module (ECM, display, or auxiliary controller) no longer transmitting on the network
• Low battery voltage or poor ground connections causing voltage drops that disrupt CAN communication protocols
• Aftermarket component installation or unauthorized wiring modifications interfering with the factory CAN network
• Software version mismatches between controllers after partial system updates or ECM replacements

How to Troubleshoot and Fix Code CID568

Step 1: Connect Caterpillar Electronic Technician (Cat ET) Software
Use genuine Cat ET diagnostic software with a communication adapter to identify which specific module is missing from the network. The software will display active and logged CID codes and pinpoint the exact controller causing the communication loss.

Step 2: Perform Visual Harness Inspection
On used excavators, thoroughly inspect the CAN bus wiring harness from the ECM to all connected modules. Focus on areas with known wear points: behind the cab near the swing bearing, along the boom where harnesses flex repeatedly, and near the battery box. Look for chafed insulation, broken wires, or green corrosion on connectors.

Step 3: Test CAN Bus Resistance and Voltage
Using a digital multimeter, measure the resistance between CAN High and CAN Low terminals at the diagnostic connector with the key off—should read approximately 60 ohms (indicating proper termination resistors). With key on, verify 2.5V nominal voltage on both lines, fluctuating during communication.

Step 4: Inspect and Clean All Module Connectors
Disconnect and inspect connectors at each control module identified in Cat ET. Clean corrosion with electrical contact cleaner and apply dielectric grease before reconnection. On used machines, connector corrosion is a leading cause of intermittent CID568 faults.

Step 5: Check Battery Voltage and Grounds
Verify battery voltage remains above 12.5V during cranking and all ground straps are tight and corrosion-free. Poor grounds can cause voltage fluctuations that disrupt CAN communication, especially on older machines with degraded cables.

Step 6: Replace Faulty Module if Necessary
If diagnostics isolate a specific failed controller, replace the module and ensure software versions across all controllers are compatible using Cat ET programming functions.

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Disclaimer: This guide provides general troubleshooting information for CID568 on Caterpillar excavators. Always consult the machine's service manual and consider professional diagnostic services for complex electrical issues, especially on used equipment with unknown service history.