Troubleshooting Ignition Issues in Welding Generators Caused by Corroded Starter Wires

Presented by Amindus Consulting and Solutions

Welding generators are essential tools in many industrial and construction settings. When they fail to start, it can halt work and cause costly delays. One common but often overlooked cause of ignition failure is corrosion in the starter wiring. This post explores a real-world case where a welding generator refused to start, revealing how corroded wires disrupted the ignition circuit. Understanding this problem helps operators and technicians diagnose similar issues quickly and prevent future failures.

Corroded starter wire causing ignition failure in welding generator

How the Problem Presented Itself

The welding generator in question would not start when the ignition key was turned. Normally, turning the key engages the starter motor, which cranks the engine. In this case, turning the key produced no starter engagement at all. This symptom suggested a failure somewhere in the starting circuit, but the exact cause was unclear.

To isolate the problem, the technician performed a direct test of the starter motor. By bypassing the ignition switch and applying power directly to the starter with a jumper wire, the starter motor engaged and spun normally. This confirmed the starter motor itself was functional.

Next, the ignition switch was tested and found to be in good condition. This left the wiring between the ignition switch and the starter motor as the likely source of the problem.

Identifying the Faulty Wire

A continuity test was performed on the positive starter wire running from the ignition switch to the starter motor. Continuity tests check if electrical current can flow through a wire without interruption. The test revealed no continuity in this wire, meaning the electrical path was broken somewhere along its length.

Further inspection uncovered severe corrosion on the wire terminals and the wire itself. The corrosion, known as vert-de-gris, is a greenish deposit that forms on copper and copper alloys when exposed to moisture and air over time. This corrosion acts as an insulator, preventing electrical current from passing through the wire.

Close-up of a worn vintage HOBART welding machine control panel

Why Copper Corrosion Interrupts Ignition Circuits

Copper wiring is widely used in electrical systems because of its excellent conductivity. However, copper is vulnerable to corrosion when exposed to moisture, salts, and other environmental factors. The corrosion forms a layer of copper salts and oxides that do not conduct electricity well.

In ignition circuits, even a small amount of corrosion can cause a significant voltage drop or complete interruption of current flow. This prevents the starter motor from receiving the power it needs to engage. Since the ignition switch and starter motor may still be functional, the corrosion in the wiring is often the hidden culprit behind starting failures.

Steps to Diagnose Corroded Starter Wires

When a welding generator or similar equipment fails to start, follow these steps to diagnose if corroded wires are the cause:

• Check starter motor operation by applying power directly with a jumper wire. If the starter runs, the motor is good.

• Test the ignition switch for proper function using a multimeter or continuity tester.

• Perform a continuity test on the starter wiring between the ignition switch and starter motor. Lack of continuity indicates a break or corrosion.

• Visually inspect wiring and terminals for signs of corrosion, discoloration, or damage.

• Clean or replace corroded wires and terminals as needed to restore conductivity.

Preventing Corrosion in Starter Circuits

Preventing corrosion in starter wires extends the life of welding generators and reduces downtime. Here are practical tips to avoid this problem:

• Use corrosion-resistant terminals and connectors, such as those plated with tin or nickel.

• Apply dielectric grease to terminals and connectors to repel moisture.

• Ensure wiring harnesses are properly sealed and protected from water ingress.

• Regularly inspect wiring for early signs of corrosion or wear.

• Replace damaged or corroded wires promptly before they cause failure.

• Store equipment in dry environments when not in use to minimize exposure to moisture.

  
  

Welding generator wiring compartment with clean terminals and protective covers to prevent corrosion

Practical Example: Repairing Corroded Starter Wire

In the case described, the technician removed the corroded wire and cleaned the terminals thoroughly. The wire was replaced with a new copper wire of the same gauge. New terminals with corrosion-resistant plating were installed, and dielectric grease was applied before reconnecting.

After reassembly, the ignition key was turned, and the starter motor engaged immediately. The generator started without any issues. This simple repair saved the equipment from unnecessary replacement and downtime.

Key Takeaways for Welding Generator Operators

• Ignition failure can result from wiring corrosion even if the starter motor and ignition switch are fine.

• Corroded copper wires develop vert-de-gris, which blocks electrical current.

• Continuity testing is essential to pinpoint wiring faults.

• Regular inspection and preventive maintenance reduce the risk of corrosion-related failures.

• Using protective coatings and proper storage conditions helps keep wiring in good condition.

Understanding how corrosion affects starter wires allows operators and technicians to troubleshoot ignition problems efficiently. This knowledge helps keep welding generators running reliably and avoids costly delays on the job.

If your welding generator won’t start, don’t overlook the wiring. Testing and inspecting for corrosion could save you time and money.