Ultimate RV Onan Generator 5000 Troubleshooting Guide (Fix the Clicking)
RV generator clicking but not starting? You’re not alone. The Onan 5000 genset is common in older rigs, and many Onan models act similarly in how they start and power up. Here’s a clear, field-tested walkthrough to diagnose that clicking noise, avoid needless parts swaps, and get back to reliable power fast.
- Power source
- Solenoid
- Control board
- Starter
- Flywheel
How the Onan 5000 Works
Core components and power flow
- The power source feeds the system.
- The control board sends a signal to the solenoid when you press Start.
- The solenoid bridges battery power to the starter.
- The starter engages the flywheel.
- The generator spins up and runs.
The solenoid’s bridge function
Think of the solenoid as a switchable bridge. When activated, it connects battery power to the starter so it can turn the flywheel with torque.
Accessing the Internals
Removing the control board
Use a Torx bit screwdriver to remove the control board cover. This exposes the solenoid, wiring, and starter connections so you can see how power moves through the system.
What you’ll see
Control board up front, solenoid nearby, starter at the back, and the flywheel behind the starter.
Real-World Troubleshooting Walkthrough
What failed and why it was confusing
The generator ran fine, then shut off. After that it made odd sounds on start, which pointed to the starter at first.
First try: new starter
A starter replacement is possible in a driveway, but it is awkward to access and much easier with two people. After installing a new unit from Amazon, the Start button did nothing. Frustration level: high. If you need one, here’s a reliable option for an Onan-compatible starter.
Bypass test that changed the plan
By applying battery voltage directly to the starter-side wire with jumper cables, the starter spun. That meant the starter and flywheel were fine. Helpful tools: quality jumper cables and a voltage meter.
Was it the Solenoid?
Swapping the solenoid
A bad solenoid seemed likely after the bypass test, so it was replaced with a new unit. The problem persisted, which suggested the solenoid itself wasn’t the issue. If you need one, try this starter solenoid for Onan setups.
Double-check before you spend more
The original solenoid tested fine and was reinstalled. Common mistakes to avoid:
- Replacing parts before testing simple power and ground.
- Ignoring corrosion under ring terminals or hidden in the cable.
For reference on what rapid clicking often means, see this iRV2 thread on “Onan generator woes… just clicks”.
The Real Culprit: Power and Ground
Quick battery test that proved the system
A car battery was connected, positive to the generator’s main terminal and negative to the RV frame ground. The generator started. That confirmed the control board, solenoid, starter, and flywheel were all good, and the issue was a bad positive or ground path.
Fixing a bad ground
The ground at the house battery bank was corroded. Cleaning the contact surfaces to bare metal restored a solid ground. After that, the clicking sound changed, but it still wouldn’t start.
The simple solution
The coach/aux battery switch on the dashboard was off while plugged into shore power. Turning that switch on brought the generator to life. If your genset only clicks, verify:
- Battery connections are clean and tight.
- Coach/aux battery switch is on.
- You have voltage at the solenoid input and output when pressing Start.
For more context on the classic clicking symptom and low voltage, this JustAnswer thread on an Onan making rapid clicking noise mirrors these findings.
A Fast Troubleshooting Flow
- Try Start with the coach/aux battery switch on.
- Clean and tighten all battery and ground connections.
- Bypass the solenoid by feeding power directly to the starter wire. If it cranks, starter and flywheel are good.
- If bypass works, test or temporarily swap the solenoid. If no change, put the original back in.
- Only then consider the control board, which can run $100 to $200. Here’s a compatible control board.
Cheaper fixes like cables and connections usually run $20 to $50 and solve most clicking issues.
If It Cranks But Won’t Run: Carburetor Time
Likely cause
If the generator turns over but won’t keep running, the carburetor may be clogged. Full removal is a pain.
Easier cleaning method
- Remove the air filter. Here’s a solid replacement air filter.
- Give a quick squirt of starter fluid into the carb throat and start it.
- While it runs, spray short bursts of carburetor cleaner. The engine may stumble, then recover.
- Repeat until you can spray for 5 to 10 seconds without the engine slowing. Expect to use about a can or more.
If you end up needing one, a new carburetor for Onan 5000 can save time.
No Priming Button? Here’s How to Start
Older setups, like a 1997 Winnebago with an Onan 5000, have no primer. Hold the Start button for a few seconds, release, then repeat 3 or 4 times so fuel reaches the carb before it catches. If you’ve found a clean priming workaround on an older Onan, share it in the comments.
Handy Tools and Parts
- Replacement parts: Starter, Solenoid, Carburetor, Control board, Electric fuel pump
- Tools and supplies: Torque screwdriver set, Ratchet set, Tune-up kit, Jumper cables, Voltage meter, Carb cleaner, Starter fluid
Pro Tips to Prevent Future Headaches
- Keep grounds and battery terminals clean and tight.
- Check the coach/aux battery switch before tearing into parts.
- Test with a spare battery when in doubt, it’s a quick sanity check.
- Amazon’s fast shipping and returns can be a lifesaver on the road.
Wrap-Up
Most Onan 5000 clicking problems come down to low voltage, bad grounds, or a disabled battery switch. Start with simple checks, use bypass tests to isolate parts, and save the control board for last. Got a smart priming tip or a win from your own rig? Drop it below and help the next RVer out.
