How do I reset the low coolant light
Major, major PITA. They work by using the coolant to conduct a very small current between the little pickup inside the radiator. If the coolant (anti-freeze) gets old and contaminated it puts a coating on the probe ... thus blocking the signal for the coolant level' You can pull the probe out (a job not for the meek) and clean it or you can just live with it because even putting fresh coolant may not make the alarm go away
The sensor is clamped to the radiator about 4 inches below the filler neck. There's a small wire clip that holds it in place. You can carefully pry the clip off to remove the sensor. But first, unplug the sensor and see if the light goes out. If so the sensor is bad. Unless you just had the radiator replaced. Then its possible that the hole for the sensor has not been drilled out and the sensor is dry. If the sensor proves to be bad, replace it. After you replace the sensor it may take a couple of days for the light to go out. The same is true after the cooling system is serviced. GM issued a service bulletin about this. It's normal, believe it or not! As Tom said, these sensors are troublesome!! HTH. -Jim
fill it up first ..bleed air out..if its still on replace the sending unit.
Kelly ... The sensor is nothing more then a piece of wire (anode) and is probably still good. If you get some Brasso it will polish up like brand new. To get that sucker out I was forced to remove the battery for access ... then they have this spring retainer that requires a minimum of 3 hands to remove while doing tricks with your wrist that a magician would envy. Getting it back in requires real dexterity ... the rectangle assembly is a press fit and an "O" ring (actually a rectangle ring) is compressed while your other hand (holding that square spring retainer) must manover under the hand retaining the assembly. I launched the spring twice before getting it secured ( probably because I'm old ). Beware that it is very secure because if it's not completely flat ... as soon as your radiator builds up any pressure it will become a projectile and shoot itself against the battery. I have assembled transmissions in almost total darkness but that little POS requires the dexterity of Houdini based on the visibility and the tiny space it's in. BTW you can't unplug it to eliminate the alarm ... reason being if you unplug it then there is no conductivity through the coolant and it thinks you have "low coolant" You can however put a 2000 Ohm resistor across the plug so it thinks it's reading coolant
Not true about unplugging the sensor and the light not going out. It will go out because the sensor completes the circuit to ground to turn the dash light on. By unplugging the sensor the ground path for the bulb is broken so it can't come on. HTH. -Jim
Interesting ,,, I unplugged the sensor on a 2002 Grand Prix and it stayed on until the resistor
Then there was a short in the wiring or instrument cluster. I unplugged the sensor on my '00 Grand Prix and the light went out. That's how I knew the sensor was bad. Both yours and mine use the same sensor. -Jim
Ok. So, I went right outside and unplugged the sensor(the second one BTW) and the light is off. That's it! Problem fixed. Enough of this; oil in the coolant, corroded sensor, worn out this and that, Dexcool (which is the best theory), crossing a 2000 ohm resistor over the contacts. Just unplug it and tape both the sensor receptacle and the pigtail well and check your coolant every month and look for leaks under the vehicle. Problem solved. We lived without these FREDs (freaking ridiculous electronic devices) before and we can now. Some of these are non essential and low coolant is one of them.
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