FC_8 Transfer Switch Fault: Briggs & Stratton Generator

What This Code Means

Your generator’s controller is unable to confirm that the transfer switch has moved to the correct position, which prevents safe automatic operation.

Understanding the FC_8 Fault

When your Briggs & Stratton home standby generator displays the FC_8 code, it’s telling you that something is broken in the communication chain between the generator and the automatic transfer switch (ATS). The ATS is the device that switches your home’s power from the utility grid to the generator during an outage. The generator’s controller needs constant confirmation that this switch is actually moving and settling into the right position—if it doesn’t get that signal, it stops the generator to prevent damage or a safety hazard.

This is a safety feature, not a glitch. The fault exists to protect your home’s electrical system and the people working on it. However, it also means your generator won’t run automatically until the problem is fixed.

What Causes FC_8 Faults

Three main culprits typically trigger this code:

Failed Auxiliary Contact in the Transfer Switch

The transfer switch contains small electrical contacts that send feedback signals back to the generator’s controller. These contacts confirm that the switch has physically moved and is now in the “generator” or “utility” position. Over time, these contacts can wear out, corrode, or simply fail. When they fail, the controller receives no confirmation signal, even though the switch may be working mechanically.

Broken or Loose Communication Wire

The wire that carries the feedback signal from the transfer switch to the generator controller can become loose, corroded, or damaged. This might happen due to vibration, age, weather exposure, or accidental damage during maintenance. A loose connection at either end—at the switch or at the generator—will break the communication chain.

Failed Control Relay

The generator’s control relay is an electrical component that processes the feedback signal from the transfer switch. If this relay fails, the controller won’t receive or recognize the signal, even if the transfer switch and wiring are working perfectly.

Diagnostic Checklist

Before calling a technician, you can perform these checks to narrow down the problem. Work safely and stop immediately if you’re unsure about any step.

Verify the transfer switch is in the correct position. Manually check that the ATS lever or dial is fully moved to the “Generator” or “Auto” position (consult your ATS manual for the correct position). Sometimes a switch can be partially stuck or not fully engaged, which the controller will detect as a fault. Gently try moving it back and forth a few times to ensure smooth operation.
Inspect all visible wires and connections. Look at the wires running from the transfer switch to the generator. Check for loose terminals, corrosion (green or white crusty buildup), or visible damage. Tighten any loose terminal screws by hand or with a screwdriver. Do not force anything—if a connection feels stuck, leave it for a professional.
Check for tripped breakers or blown fuses. Look at your home’s main electrical panel and the transfer switch panel. Confirm that no breakers are in the “off” or tripped position. If a breaker is tripped, switch it fully off, then back on. If it immediately trips again, stop and call a professional.
Power cycle the generator controller. Turn off the generator and disconnect the 12V battery (if accessible) for 30 seconds, then reconnect it. This resets the controller and clears temporary glitches. Restart the generator and check if the fault code returns.
Inspect the transfer switch for visible damage. Look for burn marks, melted plastic, or unusual discoloration on the switch itself. These signs indicate internal failure and mean the switch needs replacement.
Test the transfer switch manually (if safe to do so). If your ATS has a manual override or test mode, engage it to confirm the switch moves smoothly and clicks into place. Listen for a solid mechanical click—a weak or absent click may indicate a failing contact.
Review recent weather or maintenance activity. Did a storm occur recently? Was any work done on your electrical system? Environmental stress or accidental damage during service can trigger this fault.

When to Call a Pro

Stop your diagnostic work and contact a qualified electrician or Briggs & Stratton dealer immediately if you observe any of the following:

Burn marks, scorching, or melted plastic on the transfer switch or wiring
Corrosion so heavy that you cannot see the terminal underneath
A breaker that trips repeatedly when reset
Any spark, smell of burning, or unusual noise from the transfer switch
The transfer switch lever feels stuck, stiff, or won’t move smoothly
The fault code persists after you’ve tightened all visible connections and power-cycled the controller
You’re unsure about any electrical connection or step

This fault involves high-voltage circuits and safety interlocks that protect your home and anyone working on it. A licensed electrician has the tools and training to safely test the auxiliary contacts, measure signal voltage, and replace failed components without creating a hazard.

Parts You May Need

Depending on the root cause, a technician may need to replace:

Transfer switch (if contacts have failed)
Control relay (if the generator’s relay is faulty)
Auxiliary contact kit (if the switch contacts alone can be replaced separately)
Communication wiring harness or individual wires
Terminal connectors or crimp terminals (if corrosion has damaged existing ones)

Frequently Asked Questions

Can I run my generator manually while the FC_8 fault is active?

Not safely in automatic mode. The fault prevents automatic transfer because the controller cannot confirm the switch position. You may be able to start the generator manually (in manual-start mode) if your system offers that option, but the transfer switch will not engage automatically. Check your owner’s manual for manual-start procedures. Automatic operation is not possible until the fault is cleared.

How much does it cost to fix an FC_8 fault?

Costs vary widely depending on the cause. A loose wire connection might only require a service call fee (typically $150–$300). A failed auxiliary contact or relay might cost $300–$800 including parts and labor. A full transfer switch replacement can range from $800–$2,500 depending on your switch model and local labor rates. Get a quote from your dealer before authorizing work.

Will the FC_8 fault go away on its own?

No. This fault indicates a real electrical problem that will not self-correct. The longer you wait, the higher the risk of corrosion spreading or a component failing completely. Address it promptly to restore automatic generator operation and avoid being without backup power during an outage.

Is the FC_8 fault dangerous?

The fault itself is a safety feature—it prevents the generator from operating in an unsafe state. However, the underlying problem (loose wiring, failed contacts, etc.) can become dangerous if left unrepaired. Loose connections can overheat and cause fires; failed contacts can prevent the transfer switch from engaging at all. Have it inspected and repaired by a professional.

Final Notes

The FC_8 transfer switch fault is your generator’s way of saying “I can’t confirm the switch is ready.” It’s a legitimate safety stop, not a false alarm. Most of the time, the fix is straightforward—a loose wire, a corroded terminal, or a failed component that a technician can identify and replace. The key is to act promptly and let a qualified professional handle the electrical work.

Disclaimer: This article provides general information about the FC_8 fault code and is not a substitute for your generator’s owner’s manual or professional service. Always consult the manufacturer’s documentation for your specific model before attempting any repairs. Electrical work on generators and transfer switches can be hazardous. If you are unsure about any step, contact a licensed electrician or authorized Briggs & Stratton dealer. Improper repair or maintenance can damage equipment, void warranties, or create safety hazards.

Source: Information adapted from official manufacturer documentation (reference). Always consult your generator owner’s manual for model-specific procedures.