Fault Code 235
Cummins Engine Control Module Low Voltage

Controller shows Fault Code 235 – ECM Power Supply Voltage Low; intermittent shutdowns or no start

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Loose ECM power or ground connections, Failing DC power relay, Weak battery or charger issues, Corroded harness connectors

How to Fix / Troubleshooting

Safety first: Disable automatic start. When working on control wiring, avoid static discharge and shorts.

  • Check ECM power: Using the wiring diagram, locate the ECM power and ground pins. Verify proper voltage and continuity with a multimeter.
  • Inspect grounds: Clean and tighten engine and frame ground points associated with the ECM.
  • Relays and fuses: Check the ECM power relay and related fuses in the control panel. Replace any that are heat-damaged or intermittent.
  • Harness inspection: Look for chafed or pinched wiring in the ECM harness. Repair or replace damaged sections.
  • Reset: Clear the fault and test run the generator, monitoring for stable ECM voltage.
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Repair Difficulty

Hard 4/5

Required Part

Engine Control Module (ECM) Power Relay
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