What is XCMG XE490D (CM2150 C/D) Fault Code 1671?

Fault Code 1671 indicates an "Engine Starter Motor Relay Circuit - Data Valid But Below Normal Operating Range" on XCMG excavators equipped with Cummins CM2150 C or CM2150D engines. This diagnostic trouble code (DTC) is triggered when the Electronic Control Module (ECM) detects abnormally low voltage or resistance in the starter motor relay circuit, preventing proper cranking operation.

This code specifically monitors the electrical pathway between the ECM, the starter relay, and the starter solenoid. The CM2150 engine control system relies on precise voltage signals to engage the starter motor safely. When voltage drops below the manufacturer's specified threshold (typically below 9-10 volts during cranking sequences), the ECM logs this fault to prevent potential starter damage or no-start conditions. For used XCMG excavators, this code is critical because it often signals deteriorating electrical connections or failing relay components that can leave operators stranded on job sites.

Common Symptoms

• No-crank or intermittent cranking condition when turning the key to start position
• Malfunction Indicator Lamp (MIL) or check engine light illuminated on the instrument cluster
• Clicking sound from the starter relay without engine turnover
• Battery voltage warning appearing simultaneously on the display panel
• Delayed cranking response requiring multiple key attempts before engine starts

Potential Causes

The most common technical failures triggering Code 1671 on used XCMG XE490D excavators include:

• Corroded or loose connections at the starter relay terminals (extremely common in machines with 3,000+ operating hours)
• Failed starter motor relay due to contact wear or coil degradation
• Damaged wiring harness between ECM and starter circuit, particularly at frame flex points near the engine mount
• Weak or failing battery providing insufficient voltage during cranking (below 11.5V under load)
• Faulty ECM starter output driver circuit (rare, but occurs in high-hour machines)
• Poor ground connections at engine block or chassis ground points affected by corrosion

How to Troubleshoot and Fix Code 1671

Step 1: Perform Visual Inspection Begin by inspecting the starter relay (typically located in the main power distribution panel near the battery box). Check all wiring harness connections for corrosion, fraying, or signs of rodent damage. On used excavators, pay special attention to connector pins for discoloration indicating heat damage or moisture intrusion.

Step 2: Test Battery and Voltage Supply Using a digital multimeter, measure battery voltage with engine off (should read 12.4-12.8V) and during cranking attempt (should not drop below 9.5V). Test voltage at the relay coil terminals while key is in start position—should read battery voltage. If voltage is present but relay doesn't click, replace the relay.

Step 3: Check Relay Operation and Circuit Continuity Remove the starter relay and bench-test it by applying 12V to coil terminals and checking continuity across load terminals. Test wiring resistance from ECM connector to relay socket (should be less than 5 ohms). Inspect ground circuit integrity by measuring voltage drop between engine block and battery negative (should be less than 0.2V).

Step 4: Verify ECM Output Signal Connect Cummins INSITE diagnostic software or compatible scan tool to read live data during cranking. Monitor the ECM starter enable output signal—should show active/high state when key is turned. If ECM signal is absent but all other circuits test good, ECM replacement may be required.

For used excavators, always clean and apply dielectric grease to all connectors after testing, as environmental contamination accelerates repeat failures.

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Disclaimer: This guide provides general troubleshooting information. Always consult the official XCMG service manual and Cummins CM2150 troubleshooting procedures for your specific machine serial number. If unfamiliar with high-current electrical systems, seek assistance from a certified heavy equipment technician to avoid injury or equipment damage.