coolant alarm setup

hi, i am trying to setup a coolant alarm for my 1998 mgf. I have sourced an oem expansion tank and sensor which is a normally open float switch. the alarm system needs a delay built into it to stop the buzzer triggering during cornering etc. I have followed this diagram and used this delay release module with the buzzer + wired to the n/o connector. (the data sheet for the drm can be found here) the problem im having is that when the float is activated and completes the circuit the buzzer only sounds for however long the drm is set to, this is the opposite of what it's supposed to do, i need it to delay setting the buzzer off for a set length of time. what have i done wrong with the wiring as im a bit lost now? thanks chris

The DRM info says "The trigger must be removed before the timing cycle starts". Therefore it is not what you want. (Correct?) I'd try a low-fuel sensor as these have inbuilt delays, though I'm not sure how they'd react to coolant/water (if conducting water was present in gas/petrol, it would generally only reach the sensor when empty...) But you need a delayed trigger that resets when the trigger is removed - a simple RC delay to a transistor etc should do. Or maybe a "resettable monostable" 555 circuit....

In retrospect, I reckon just mount the switch deeper.... It isn't worth going to too much trouble for an overflow bottle unless you are monitoring the radiator level - afterall, that is the critical issue. (Yes - I have seen several cooked engines that have adequate water/coolant in their expansion/overflow bottles. It will still annoyingly flash on, but hopefully only when its rest level is below "full" or upper. And hopefully it will come on (at rest) before the low level. And when you top it up, you can also check the radiator's level, or figure out why you have lost fluid....