Komatsu PC160LC-7 Fault Code DA2SKQ: Complete Diagnostic Guide

What is Komatsu PC160LC-7 Fault Code DA2SKQ?

Fault code DA2SKQ indicates a communication error between the Engine Control Module (ECM) and the Machine Controller on the Komatsu PC160LC-7 excavator. This specific code signals that the CAN bus communication network has detected intermittent or complete loss of data transmission between these critical systems.

This fault is particularly serious because the ECM and Machine Controller must constantly exchange information about engine parameters, hydraulic demands, and operating conditions. On the PC160LC-7's SAA4D102E-2 engine platform, this communication failure can trigger protective derate modes that limit machine performance to prevent potential damage. The CAN (Controller Area Network) system operates at specific voltage levels (typically 2.5V differential), and any disruption compromises the entire machine management system.

Common Symptoms

When fault code DA2SKQ is active, operators typically experience:

• Engine derate or limited power output, with the machine unable to reach maximum RPM or hydraulic flow
• Multiple warning lights illuminated simultaneously on the monitor panel, including check engine and system error indicators
• Intermittent loss of monitor display information, such as missing fuel level, temperature readings, or hour meter data
• Erratic hydraulic response or inconsistent swing/boom/bucket operation due to controller communication gaps
• Difficulty starting or unexpected engine shutdown, particularly after the machine has been operating normally

Potential Causes

The most common technical causes for DA2SKQ on used PC160LC-7 excavators include:

• CAN bus wiring harness damage at known rub points near the engine firewall and along the right-side frame rail where harnesses contact structural members
• Corroded or loose connectors at the ECM (located behind the operator cab) or Machine Controller connections, especially on machines with 5,000+ operating hours
• Failed terminating resistors in the CAN network—the PC160LC-7 uses 120-ohm resistors at network endpoints that deteriorate over time
• ECM or Machine Controller internal failure, particularly in excavators exposed to high-vibration applications like rock excavation
• Voltage supply issues from the main power harness, causing insufficient power to maintain stable CAN bus communication (requires 9-16V DC)
• Aftermarket monitor installations or previous electrical repairs that compromised original CAN bus integrity

How to Troubleshoot and Fix Code DA2SKQ

Step 1: Visual Harness Inspection Begin with a thorough physical examination of the CAN bus wiring harness. On used excavators, focus on the harness routing from the ECM to the Machine Controller. Check the yellow and green CAN High/Low wires for abrasion damage where they pass through the engine compartment bulkhead. Inspect all connector pins for corrosion (green/white deposits), bent contacts, or moisture intrusion. Pay special attention to the 6-pin connector at the ECM and the multi-pin connector at the controller behind the cab.

Step 2: CAN Bus Resistance Testing Using a digital multimeter (DMM), disconnect both the ECM and Machine Controller connectors. Measure resistance between the CAN High and CAN Low terminals—you should read approximately 60 ohms with both ends disconnected (indicating two 120-ohm terminating resistors in parallel). If you measure 120 ohms, one terminating resistor has failed. Open circuit (OL) indicates wiring break or both resistors failed. This is critical on used machines where vibration degrades resistor solder joints.

Step 3: Voltage and Signal Quality Check Reconnect the system and measure CAN bus voltage with the key on, engine off. Between CAN High and ground, you should see approximately 2.5-3.5V DC; CAN Low should read 1.5-2.5V DC. The differential voltage (CAN High minus CAN Low) should be around 2.0-2.5V. Use Komatsu KOMTRAX diagnostic software or a compatible J1939 scanner to monitor live CAN bus traffic and identify communication dropout patterns.

Step 4: Controller Power Supply Verification Verify that both the ECM and Machine Controller are receiving stable voltage. Check the main 24V power supply (PC160LC-7 uses 24V system) at both controllers—voltage should remain between 22-28V during cranking and operation. Inspect ground connections at the ECM mounting bracket and controller chassis ground points, cleaning contact surfaces and applying dielectric grease to prevent future corrosion.

Step 5: Component Replacement Protocol If wiring and power supply check good, suspect controller failure. On used excavators, before replacing expensive controllers, perform a controller swap test if possible. Replace terminating resistors first (under $20 each) before condemning controllers. If ECM replacement is necessary, ensure the replacement unit is programmed with the correct machine software version—Komatsu dealers can verify compatibility using the machine serial number.

Critical Note for Used Equipment: Excavators with extensive hours often have multiple previous repairs. Always check for non-OEM wiring splices, incorrect gauge wire repairs, or missing shielding on CAN bus cables that may cause intermittent faults.

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Disclaimer: This guide provides general troubleshooting information for experienced technicians. CAN bus diagnostics require proper training and equipment. Always consult the official Komatsu PC160LC-7 service manual and consider professional diagnosis for complex electrical issues. Improper repairs can cause additional system damage or create safety hazards.