Low coolant light on, but tanks is full. [Archive] - GrandAmGT.com Forum


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08-29-2004, 05:54 PM
Info: 1994 Grand Am, 3.1L. Past week I replaced the heater core (no fun), and everything is working fine.

heat works, coolant resevoir is full. For some reason, the "low coolant" light is still staying on... mind you... today is when i finished and i've been letting it run for the past ~15 mins. Any ideas?

08-29-2004, 09:15 PM
The resevoir is still full even after its been running for 15 minutes? Normally I'd say that you need to let it run for a while, & let the motor suck in some coolant, then check the resevoir. However, it seems you've done that. I lost a bunch of coolant a while back, and when I filled it back up to full, my "low coolant" light came on, but I just poured in a full glass of water to "top it off", and the light went off. Its done that to me twice. I'm not sure about yours. Maybe somehow your coolant is not getting to where it needs to be and the computer is registering as low. I'm sorry, I'm just not exactly sure on this one.

08-29-2004, 09:32 PM
Mine did this when i cleaned out the tank. I let the car run for a long time and even took it for a ride. The light wouldnt go off. I let the car keep running and took the screws off that hold the tank on and gently shook the tank. The light went off after that.

08-29-2004, 09:39 PM
after I tore-down my 2.4L and rebuilt it, it took quite a few miles before the "low coolant" light went out. I don't know why, it just takes it's time.

If the resevoir is full, the engine isn't overheating, and the hvac blows hot air when the heat is on - then you're fine.

08-29-2004, 09:41 PM
Air pockets

08-29-2004, 10:31 PM
The resevoir is known to get dirty where the sensor is, and tends to get stuck down. Pull it out, run water thur it upside down and tap the sensor.

08-30-2004, 01:31 AM
I was suspecting air pockets and just plain dirty sensors being the cause. (How would the air pockets get fixed? on its own, over time? or do I actually have to do something?)

Engine isnt over heating and heat is working perfect thanks to my hossy touch. :)

Tomorrow i plan to take her out for a couple miles and see if the light goes out... if not.. i'll just break it.

This beast has 136k on it so me and my bro are pretty happy so far.

Thanks chieftans. :ec:

08-30-2004, 04:27 AM
Let the motor heat up to normal operating temp, then open the release valve on top of the black pipe on the water pump.

08-30-2004, 10:22 AM
Let the motor heat up to normal operating temp, then open the release valve on top of the black pipe on the water pump.

that sounds uber dangeresque! Engine hot... me touching stuff. :hang:

On another note... dont cars usually have a cap on top of the radiator?

08-30-2004, 10:29 AM
Yes, they usually do. But we dont.

08-30-2004, 10:42 AM
radiator caps are for pussies...

08-30-2004, 11:04 AM
radiator caps are for pussies...

like me :metal:

09-01-2004, 07:31 PM
Might be a stuck fault code. Try disconnecting the battery wire for at least 10 minutes, reconnect and see if the light goes out. Don't forget to jot down your stereo presets before disconnecting the battery.


09-01-2004, 07:44 PM
radiator caps are for pussies...


thats good stuff, i dont care who ya are thats funny.

09-02-2004, 01:00 PM
K, someone give me some more options. I drove it about 10 miles today... still on and the resevoir is still near full.

I took out the coolant tank, ran hose water thru it and shook the shat out of it and could here the sensor being loosened up. Got tons of crap out too.

I let the car get to normal running temp, then released the valve on the water pump to get rid of any air pockets.

The light is still on... :(