Weil McLain 381-359-447 Wiring Harness

The Weil McLain 381-359-447 Wiring Harness, Control to Junction Box is the OEM wire harness that ties the boiler's junction box to its control module. Weil-McLain's online parts catalog lists 381-359-447 on the control parts page for the EG-45 in the EG Series 7, a natural gas water boiler, both with and without the tankless heater. It is a small part, but the control module depends on it for the power and signal path back to the junction box, so a tired harness can cause problems that look like a bad module.

The harness is a pre-built assembly: black, white and green leads, a metal conduit connector at one end, ring terminals, and a white multi-pin plug at the other. That means there is no cutting, splicing or crimping, and the terminated ends land where the factory harness did. Match it by boiler model and not by the word "harness" alone, because Weil-McLain uses different harnesses on different boiler families and sizes. The application confirmed here is the EG-45, so for any other EG size, check the model number and serial number on the boiler before you order.

When a boiler shows a dead control, intermittent lockouts or a module that seems to lose power when the wiring is touched, inspect the harness before you condemn the control module. Look for chafed insulation at the conduit connector, heat damage on the leads, a loose or backed-out pin in the multi-pin plug, and a ring terminal that has worked loose under its screw. With the power off and locked out, check each lead for continuity end to end. To replace it, disconnect the electrical supply, label or photograph the terminal positions, remove the old harness from the junction box and the module, fit the new 381-359-447, secure the conduit connector, restore power and run a call for heat to confirm a normal ignition sequence.

Key Benefits

• Factory-built harness: The 381-359-447 comes with its leads, ring terminals, conduit connector and multi-pin plug already assembled, so there is nothing to splice.
• Matches the Weil-McLain parts catalog: It is the part Weil-McLain lists as the control to junction box wiring harness for the EG-45 natural gas water boiler.
• Saves a misdiagnosis: A worn harness is a small repair compared with replacing a control module that was never actually bad.
• Clean, secure connections: The metal conduit connector and terminated leads keep the junction box wiring tidy and protected.

Common Questions

What does the 381-359-447 connect?
It connects the boiler's junction box to the control module. It is described as a wire harness, junction box to module.

Which boilers use the 381-359-447?
Weil-McLain's parts catalog shows it for the EG-45, EG Series 7, natural gas water boiler, with and without the tankless heater. Confirm any other boiler by model number and serial number before you order.

How do I know if the harness is the problem?
Check for chafed or heat-damaged insulation, a loose pin in the multi-pin plug, a loose ring terminal and any lead that fails a continuity test with the power locked out.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.