What is Komatsu PC70-8 Fault Code AB00KE?

Fault Code AB00KE indicates a communication error between the engine ECM (Engine Control Module) and the machine's main controller or monitor panel. This diagnostic trouble code (DTC) specifically points to an interrupted or degraded data link within the CAN (Controller Area Network) bus system that enables critical machine systems to share operational data.

In the Komatsu PC70-8, this code affects the SAE J1939 communication protocol, which synchronizes engine performance parameters with hydraulic system demands and operator display functions. When this communication pathway fails, the excavator cannot properly coordinate power delivery, potentially leading to operational restrictions or complete machine shutdown. This is particularly critical in compact excavators like the PC70-8, where integrated control systems manage fuel efficiency and hydraulic response simultaneously.

Common Symptoms

• Warning lamp illumination on the instrument cluster, often accompanied by a wrench or diagnostic icon
• Intermittent or complete loss of engine data on the monitor display (RPM, coolant temperature, fuel level showing dashes or zeros)
• Engine derate or limp mode activation, limiting maximum RPM to 1500-1800 range
• Erratic hydraulic response, especially during combined functions like swing-and-dig operations
• Inability to read additional diagnostic codes through the machine's self-diagnostic system

Potential Causes

The AB00KE code typically stems from issues common in used excavators with 3,000+ operating hours:

• Corroded or damaged CAN bus connectors behind the operator cab or near the engine firewall—known wear points on PC70-8 models
• Chafed wiring harness where cables route along the swing bearing or through cab mounting brackets
• Failed termination resistor (120-ohm) at either end of the CAN network
• ECM internal communication module failure, particularly in machines exposed to high-moisture environments
• Voltage supply issues from the main power harness (low battery voltage below 22V on 24V systems)
• Aftermarket monitor installations that improperly tap into the CAN network without proper isolation

How to Troubleshoot and Fix Code AB00KE

Step 1: Visual Harness Inspection Begin with a thorough physical inspection of the CAN bus wiring (typically twisted orange/green pair). Focus on areas where the harness passes through metal grommets near the swing post and along the engine compartment firewall. Look for abraded insulation, pinched wires, or evidence of rodent damage common in stored equipment.

Step 2: Connector and Termination Check Disconnect the 8-pin Deutsch connector at the ECM and the monitor panel. Inspect for green corrosion (copper oxidation) on pins 3 and 5 (CAN-H and CAN-L). Clean with electrical contact cleaner and dialectric grease. Using a digital multimeter, measure resistance between CAN-H and CAN-L terminals with all modules disconnected—you should read approximately 60 ohms (two 120-ohm resistors in parallel). Any reading above 80 ohms or below 50 ohms indicates termination resistor failure.

Step 3: Voltage and Signal Testing With ignition on (engine off), measure voltage at the ECM connector. Pin 1 should show 24V (±2V) and ground pins should read 0.2V or less. For used excavators, also check for voltage drop under cranking—anything below 20V suggests weak batteries or poor ground connections affecting CAN stability.

Step 4: Software Diagnostics Connect Komatsu KOMTRAX diagnostic software or a compatible J1939 reader. Monitor live CAN bus traffic—message error counters above 5% indicate active communication disruption. Clear codes and operate the machine through various functions while monitoring. Intermittent code returns strongly suggest harness flexing issues rather than hard component failures.

For used excavators specifically: Before replacing the ECM (a $1,200-2,500 component), always substitute a known-good monitor panel first, as display unit failures can mimic ECM communication errors at 30% of the cost.

---

Disclaimer: This guide provides general diagnostic procedures. Complex electrical issues may require manufacturer-specific tools and trained technicians. Always consult Komatsu service documentation and qualified diesel mechanics for definitive repairs on critical machine systems.