Caterpillar Excavator Fault Code 2913-6: Meaning, Symptoms & Fix

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What is Caterpillar Fault Code 2913-6?

Caterpillar fault code 2913-6 indicates a current below normal condition on the Machine Security System (MSS) module output circuit. Specifically, this code is triggered when the ECM (Engine Control Module) detects that the current flowing through the MSS output circuit has dropped below the manufacturer's acceptable threshold.

This fault directly impacts the machine's anti-theft and operational authorization system. On used Caterpillar equipment, this code is particularly critical because an unresolved MSS fault can prevent the engine from starting entirely or cause intermittent shutdowns during operation.

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Common Symptoms

When fault code 2913-6 is active, operators typically experience the following:

• Warning lamp illumination on the instrument cluster, often accompanied by an active fault alert
• Engine cranks but fails to start, or starts briefly before shutting down due to security lockout
• Intermittent power loss or unexpected machine shutdowns mid-operation
• Cat ET diagnostic software displays an active or logged 2913-6 fault with no clear operator-side cause
• Reduced machine functionality, with some electrical systems behaving erratically

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Potential Causes

Several technical factors commonly trigger this fault, especially on used or older Caterpillar machinery:

• Failed or degraded MSS module with internal circuit breakdown
• Open circuit or short to ground in the MSS output wiring harness
• Corroded or damaged connector pins at the MSS module or ECM interface
• Chafed wiring harness caused by friction against frame components — a known issue in high-hour machines
• Faulty ECM output driver unable to maintain proper current supply to the MSS circuit
• Previous unauthorized repair attempts that disrupted the security system wiring integrity

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How to Troubleshoot and Fix Code 2913-6

Step 1 – Connect Cat ET Diagnostic Software Connect a laptop running Caterpillar ET (Electronic Technician) software via the service port. Confirm the fault code, check whether it is active or logged, and review any related fault codes that may point to a broader electrical issue.

Step 2 – Inspect the Wiring Harness and Connectors On used excavators, harness wear is the first priority. Physically trace the MSS module wiring from the module to the ECM connector. Look for chafing, exposed copper, corrosion on pins, or moisture intrusion in connectors. Clean corroded pins with electrical contact cleaner before drawing any conclusions.

Step 3 – Perform Circuit Resistance and Voltage Checks Using a digital multimeter, measure resistance across the MSS output circuit. Compare readings against Caterpillar's service manual specifications. An open circuit (OL reading) confirms a wiring break; a near-zero resistance reading may indicate a short to ground.

Step 4 – Test the MSS Module If wiring checks out, isolate the MSS module and test its output signal directly. A module with no output signal under correct supply voltage should be replaced with a genuine Cat-spec unit.

Step 5 – Clear Faults and Verify After repairs, clear all fault codes using Cat ET and perform a full operational test to confirm the fault does not return.

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Disclaimer: This guide is intended for informational purposes and general diagnostic direction. Always consult a certified Caterpillar dealer or licensed heavy equipment technician for definitive repairs, particularly on security system components. Improper handling of the MSS system may result in permanent machine lockout.