Tennant T300 & T300e Troubleshooting Guide: How to Fix the 9 Most Common Issues

When a commercial floor scrubber goes down, it doesn’t just disrupt your cleaning schedule, it can create a serious safety hazard. The Tennant T300 and T300e are incredibly reliable automatic scrubbers, but regular wear and tear can eventually cause performance issues or trigger digital error codes.

Before you call out an expensive service technician, many common floor scrubber issues can be diagnosed and fixed right on your shop floor.

Safety First: Before performing any maintenance or troubleshooting on your Tennant T300, stop the machine on a level surface, turn the key switch OFF, remove the key, and set the parking brake (if applicable). If you are inspecting internal or electrical components, always disconnect the battery cables and charger cord first.

Here is how to solve the 9 most common issues reported by Tennant T300 owners.

1. Battery or Charging Issues

• The machine won’t turn on or has a dead dashboard: Check for loose, dirty, or corroded battery cable connections. If you see white or green powder, clean the terminals with a strong mixture of baking soda and water. Also, ensure the machine is not actively plugged into the wall; the T300 features a built-in charger interlock that prevents the machine from operating while charging.
• Short run-times / batteries won't hold a charge: If you use flooded lead-acid batteries, check the water level weekly. Add distilled water after charging, making sure the fluid just covers the lead plates. If your on-board charger flashes Error Code 0xF104, the charging timer has exceeded its maximum cycle, usually indicating the batteries have reached the end of their lifespan and need to be replaced.
• The charger won’t start: Verify the wall outlet has active power. If the on-board charger flashes Error Code 0xF102, it is overheated. Move the scrubber to a cooler, well-ventilated area and allow it to cool down before restarting.

2. Leaking Water or Leaving Streaks

• Check for trapped debris: Debris frequently catches under the squeegee blades. Wipe down both the front and rear blades with a clean cloth daily.
• Inspect blade edges: Look closely at the wiping edges for small nicks, tears, or rounded corners. The T300 squeegee blades feature a smart design with four usable wiping edges. If one edge is worn, simply flip the blade end-for-end or top-to-bottom before buying a replacement.
• Are you using conventional floor soap with ec-H2O? If your machine uses ec-H2O NanoClean technology, you must use clean, cool water only. Adding conventional floor detergents breaks down the electronic treatment system and triggers a system fault (a blinking red ec-H2O light or Error Code 0x0708). If soap was added accidentally, completely drain, flush, and refill the solution tank.

3. Squeegee Damage

• Wavy or warped blades: If the rear squeegee rubber is physically damaged or warped, it won't create the necessary seal with the floor. To swap it, loosen the two outside yellow adjustment knobs on the assembly to separate the blade retainer from the frame.
• Clean the integrated reservoir: Sludge and heavy grit can build up inside the squeegee assembly itself, distorting airflow. Weekly, pull off the yellow drip trap cover located in the center of the squeegee frame and thoroughly clean out the internal reservoir.

4. Not Picking Up Water (Leaving a Wet Surface)

An automatic floor scrubber must maintain 100% water recovery—there should be no visible standing water left behind on the floor. If your machine is leaving a wet trail, check these areas:

• The recovery tank is full: When the recovery tank fills to capacity, the built-in ball float rises to block the vacuum intake. Drain the recovery tank completely at an approved disposal site.
• Clean the float shut-off screen: Pull out the mesh cylinder screen located inside the recovery tank lid. Wash away any lint, foam, or debris blockages, and empty the small debris tray.
• Inspect the lid gasket: Look at the large rubber seal running around the underside of the recovery tank lid. If it is cracked, crushed, or pulled out of its channel, it will leak vacuum pressure and drastically reduce suction.
• Turn off Quiet-Mode: If the green ear icon is lit on your control panel, the machine is running in Quiet-Mode. This lowers the vacuum motor speed to reduce noise, which naturally lowers water pickup on rough or heavy-traffic floors. Turn it off for maximum suction power.

5. Not Putting Out Water

• Clean the solution filter: Locate the clear plastic filter bowl underneath the rear frame of the machine. Drain the solution tank, unscrew the filter bowl counter-clockwise, remove the internal stainless steel screen, and rinse away any clogging sediment.
• Tripped circuit breaker: Open the battery compartment and locate the circuit breaker panel. If breaker CB2 (which controls the solution valve and ec-H2O system) is extended outward, let it cool down for a minute and push it firmly back inward to reset it.
• Check your operation sequence: On propel models, water will not dispense if the machine is sitting stationary in neutral. You must lower the scrub head and pull the control handle start bail forward to activate the solution flow.

6. Brush Motor Issues

• Bail Sequence Error (Code 0x0902): If your dashboard flashes error code 0x0902, it means the handle start bail was pulled before the key switch was turned to the ON position. Turn the key off, release the handle bail completely, make sure nothing is mechanically binding the handle, and turn the key back on.
• Overcurrent Faults (Codes 0x0103 / 0x0104 / 0x0105): These codes mean the brush motor is drawing too much electric current. This typically happens if your down-pressure setting is too aggressive for the type of floor you are scrubbing, or if a pad driver is catching on rough concrete. Lower the scrub head down-pressure setting using the dashboard control panel.
• Check the drive belts: If you have a dual-disk or cylindrical machine and one brush is completely stationary while the motor runs, the internal drive belt is likely slipping or broken and needs to be serviced.

7. Making Strange Noises

• Debris entanglement: High-pitched squealing or grinding from underneath the machine is usually caused by plastic banding, string, or shrink-wrap wrapping around the brush spinners and drive hubs. Remove the brushes and clear away any trapped material immediately to protect the motor seals.
• Loud rattling from an orbital head: If you operate a T300 with an orbital scrub head and it begins producing a loud, metal-on-metal shaking noise, the four lower rubber vibration isolators are likely worn down. These isolators are wear items and are scheduled to be replaced every 500 working hours.
• Howling from the vacuum fan: If a loud whine or howling noise comes from the top of the machine when the vacuum turns on, check the fan chamber for debris. If the fan blades do not spin completely freely by hand, the vacuum motor assembly needs replacement.

8. Impact Damage

• Damaged side skirts: Bumping into walls, pallets, or door frames can bend the metal scrub deck edge or tear the rubber splash skirts. Inspect the side skirts daily; if they are torn or sagging, water will escape out the sides of the scrub head before the rear squeegee has a chance to reach it.
• The machine is completely dead after a bump: If the machine suffered an impact and the entire dashboard display is dead, check to see if the optional red Emergency Stop button on the handle console was accidentally depressed. Twist the red button clockwise to pop it back out, then cycle the key switch to restore power.

9. Key Broken in Switch

• Isolate power immediately: Disconnect the main battery cable plug inside the battery compartment to ensure the machine cannot accidentally engage or move while you work on the dash console.
• Removing the broken blade: Use a T25 star screwdriver to remove the mounting screws at the base of the control console shroud, then lift the shroud to access the back of the key switch. If you cannot pull the broken key blade out from the front face using needle-nose pliers or a key extractor tool, the mechanical key switch cylinder must be unbolted and replaced as a complete assembly. 

Looking for additional information? Check out our additional blogs around troubleshooting your Tennant T300/T300e floor scrubbers:

• Part 1: Tennant T300/T300e: Electrical Diagnostics Multimeter Setup & Voltage Drop Testing
• Part 2: Tennant T300/T300e: Electrical Diagnostics Wiring Harness & Sensor Testing
• Part 3: Tennant T300/T300e: Decoding Tennant T300 Fault Codes & Control Board Isolation

Need Replacement Parts or Expert Advice?

Regular maintenance is the easiest way to prevent unexpected downtime. Keep your Tennant T300 running like new with high-quality replacement parts.

From replacement squeegee blades, splash skirts, and filters to new batteries and brush motors, SweepScrub has everything you need to maintain your equipment.

Browse our full inventory of Tennant T300 / T300e Replacement Parts here or contact our support team today if you need assistance diagnosing a complex service issue!