'Coolant shortage indicator' (low coolant level circuit)
Posted: 30 May 2021, 10:44
Morning all, hope we've been enjoying the Bank Holiday sunshine?
I have a slight weep on the above sensor (through the terminals) in the pressurised coolant tank. Whilst waiting for Brickwerks to restock the sensor, I've had a checkthrough the rest of the circuit to ensure it works, as I'm always on high alert when it comes to all things cooling system. It turns out it doesn't work.
My understanding is the red LED over the coolant temperature guage should flash if there is a low coolant level (and doubles up as an overheating warning as well). The sensor is nice and simple (two prongs that sit in the coolant presumably making the circuit unless the level drops), I've check continuity of the supply and earths at the sensor connection, back to the large engine bay connection box, and gave the local earths a good clean up anyway, as you need to feel you're doing something helpful.
Voltage on the supply seemed to be 120mV, but thinking this through I'm not expecting 12V as this would end up with a short-circuit as the prong sits in the coolant, which flows around the (earthed) engine. Same voltage was found for the same cable at the fuse box.
Leaving the sensor connection disconnected, linked out or earthed doesn't seem to produce any flashing LED warning.
Red LED flashing pre-start test when you first switch the ignition on seems to work OK, and it works OK if I ground the temperature sensor.
The Haynes circuit diagram doesn't make things any clearer at all to me (sensor is F66) as it doesn't show a connection to the fuse box, but I've found the same cable colour and voltage at the fusebox.
Any experience or wisdom as to why the coolant level circuit can't be forced to show a warning?
Many thanks in advance.
I have a slight weep on the above sensor (through the terminals) in the pressurised coolant tank. Whilst waiting for Brickwerks to restock the sensor, I've had a checkthrough the rest of the circuit to ensure it works, as I'm always on high alert when it comes to all things cooling system. It turns out it doesn't work.
My understanding is the red LED over the coolant temperature guage should flash if there is a low coolant level (and doubles up as an overheating warning as well). The sensor is nice and simple (two prongs that sit in the coolant presumably making the circuit unless the level drops), I've check continuity of the supply and earths at the sensor connection, back to the large engine bay connection box, and gave the local earths a good clean up anyway, as you need to feel you're doing something helpful.
Voltage on the supply seemed to be 120mV, but thinking this through I'm not expecting 12V as this would end up with a short-circuit as the prong sits in the coolant, which flows around the (earthed) engine. Same voltage was found for the same cable at the fuse box.
Leaving the sensor connection disconnected, linked out or earthed doesn't seem to produce any flashing LED warning.
Red LED flashing pre-start test when you first switch the ignition on seems to work OK, and it works OK if I ground the temperature sensor.
The Haynes circuit diagram doesn't make things any clearer at all to me (sensor is F66) as it doesn't show a connection to the fuse box, but I've found the same cable colour and voltage at the fusebox.
Any experience or wisdom as to why the coolant level circuit can't be forced to show a warning?
Many thanks in advance.