Johnson Pump 36303 Ultima Automatic Switch

The Johnson Pump 36303 Ultima Automatic Switch (SKU: 189-36303) is an electronic bilge pump switch designed for automatic operation. It uses patented Mirus field effect detector cells to sense disruptions caused by water and fluidswithout moving parts, mercury, or exposed sensors.

Key Features

• Patented Mirus field effect detector cells detect disruptions caused by water and fluids
• Solid-state design with no moving parts
• Totally sealed detector cells never in direct contact with water
• Will not corrode and is not affected by oil or foreign debris
• No mercury and no exposed sensors help eliminate corrosion possibilities
• Automatic activation and deactivation levels designed for bilge use (activates at 2″ fluid level and deactivates at 3/4″ fluid level)
• 3-second delay helps prevent false starts from water sloshing

Product Compatibility

• Automatic control for marine bilge pumps (switch-to-pump automatic operation)
• Bilge pump systems that use a compatible electronic automatic switch setup

Product Details

• Brand/Model: Johnson Pump 36303 Ultima Automatic Switch
• SKU: 189-36303
• Type: Ultima Switch Electronic Automatic Switch
• Operation: Automatic bilge sensing and switching (activates at 2″ fluid level; deactivates at 3/4″ fluid level)
• Protection timing: 3-second delay to help prevent false starts
• Electrical rating (12V/24V): rated to handle pumps up to 20A at 12V or up to 10A at 24V
• Construction/sensing: sealed Mirus field effect detector cells; no moving parts; no mercury; no exposed sensors
• Switch behavior and switching is designed for use as an automatic switch component with compatible Johnson Pump marine bilge pump systems

Parts Desk Insights

Best Use Case: Great for replacing an existing Ultima-style electronic bilge switch when you want automatic water sensing with a solid-state, sealed detector design.

Common Issues: If your bilge pump doesnt cycle as expected, confirm the wiring connections and that the switch is mounted/positioned correctly in the bilge. Also inspect for debris at mounting areas and verify the unit is clean and dry where it should be, since water slosh can trigger undesired cycling if the system is disturbed.

Related Products & Accessories

• Browse Bilge Pump Switches & Circuit Protection – If youre sourcing additional control components for a complete automatic bilge pumping setup, explore the related bilge pump switch category.