Bolec WL601 Low Coolant Level Alarm
Easy DIY install • Epoxy-encapsulated durability • 7-second slosh delay
Engine overheating almost never happens at a “good” time. The real problem isn’t the temperature spike—it’s the surprise. The Bolec WL601 Low Coolant Level Alarm is designed to remove the surprise by warning you early, before heat becomes damage. Built for 12/24 VDC negative-ground systems, WL601 brings reliable level sensing to passenger vehicles, trucks, buses, agricultural and industrial engines, marine diesels, and even off-grid or caravan water tanks.
Why WL601?
1) Anyone can install it
Power, ground, alarm output, and the supplied probe—just four simple connections. Mount the compact module under-dash, connect ignition-switched power, add a lamp/buzzer or relay, and run the probe lead. That’s it.
2) Epoxy-encapsulated
WL601’s electronics are fully potted in epoxy. That means excellent resistance to vibration and moisture—ideal for harsh duty cycles, dusty sheds, salt air, or long-haul corrugations.
3) 7-second slosh delay
Fluid sloshes in corners, up slopes, and over rough ground. WL601 waits ~7 seconds before alarming after the level drops below the probe, which dramatically cuts false alerts while still catching real low-level events quickly.
How it works (simply)
WL601 measures the conductive path through coolant to the radiator’s grounded body. When coolant covers the probe, the module holds the normally open relay off. If level falls below the probe, resistance rises and—after the built-in delay—the relay switches to ground to drive your indicator or buzzer.
Typical applications
- Low radiator level alarm for cars, 4×4s, trucks, buses
- Coolant-level protection for industrial, agricultural, and marine engines
- Auxiliary tanks: long-range or caravan potable water (level warning)
- Simple pump control with two units acting at high/low points
Quick DIY install (at a glance)
- Mount the module under the dash; orientation isn’t critical.
- Connect
IGN+to an ignition-switched 12/24 V source (2 A fuse). - Connect
GNDto a solid chassis ground. - Wire
ALARMto the negative side of your lamp/buzzer/relay (up to 1.5 A resistive). Add a diode across coils. - Fit the supplied probe ~13 mm (½″) above the radiator core, away from hose entries. Refill coolant.
- Test by briefly removing the probe wire with ignition on—the LED and alarm should trigger after ~7 seconds.
Spec highlights
- Voltage: 12/24 VDC (negative ground)
- Output: N/O relay to ground, 1.5 A resistive
- Delay: ~7 s slosh-filter on falling level
- Construction: Epoxy-encapsulated module, indicator LED
- Compact: ~58 × 42 × 29 mm
FAQ
Will it work with both 12 V and 24 V vehicles?
Yes—WL601 accepts either 12 or 24 VDC negative-ground systems.
Can it run a relay for a siren or dash lamp?
Absolutely. The output relay switches to ground (1.5 A resistive). For coils, fit a reverse-EMF diode.
What about false alarms on rough roads?
The built-in ~7 s slosh delay filters transient dips so you only hear an alert when level is genuinely low.
Ready to protect your engine?
WL601 is a “fit-and-forget” safeguard that pays for itself the first time it prevents an overheat.