Low coolant sensor

[sleepy34]

Light is on all the time . I have 1994 cutlass quad 4. Where is the sensor? does anyone know part #?

[PACNWDude]

Don't know the part number, but Dex-cool may have gummed up over it too. Why I flush out Dex-cool in all GM products when new. Can gunk up many other parts of the cooling system as well. So cleaning the sensor may help.

[sleepy34]

where is it located? Is it on passenger side of rad? Do I need drain system to clean it?

[ron350]

Yep sensor is a square black plastic box thingy about the size of a matchbox located on the passengers side of the radiator.

Yes you need to drain the radiator before removing the sensor.

 

The sensor has a single copper sensing post that looks like it is plated with nickel.

When the sensor is covered with coolant it sees a ground path through the coolant and keeps the low coolant light off. When the coolant drops below the copper post it loses its ground path and causes the low coolant light to come on.

 

When the coolant gets old and corrosive it eats the plating off the copper post and the copper post becomes coated with green corrosion and the low coolant light turns on.

If you put a new sensor in without replacing the old corrosive coolant the new sensor wont last long before the protective plating is eaten of the copper and the post turns green again.

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These sensors also have a high electronic failure rate with or without the corroded copper post so if you go to the salvage yard pick up several.

I can test a sensor by plugging it in and connecting a jumper wire from the copper post on the sensor to chassis ground and turning the ignition switch to run. So far 50% of the salvage yard sensors have tested bad.

 

The sensor has a wire retainer clip that holds it in the radiator. You need to unhook the wire clip from the sensor and remove it before removing the sensor.

Be careful prying the sensor out of the side of the radiator or you will crack the plastic radiator.

The sensor has two rubber o-rings around the neck that plugs into the radiator. The two o-rings need to be lubed with spark plug boot grease or white grease before attempting to push it into the radiator hole.

[sleepy34]

You know I have researched this all summer and you are the first person with an intelligent answer on where it is and how to replace it properly. I am going to buy the part new and replace the replace the fluids. I have had this car more than 4 years and have had to do many repairs on it. Most things I have found on the net or here. For some reason I could not find info on this issue until now. A great big THANK YOU to you my friend:thumbsup:

[rich_e777]

Post an introduction and ask any questions you like, sometimes threads get over looked but its not intentional. Just to add on you shouldn't have to drain the entire radiator just lower the coolant level below the sensor, and when you do unclip it the O-ring tends to hold the sensor in pretty good so gently rock it back and forth. Before rushing out to but a new one try cleaning your current one out. Ive had this issue before and cleaning it out fixed the problem, but I had also changed the coolant at the same time and upgraded the radiator not long before that.