Coolant light stays on with no leaks in system

[primalnick]

Hey guys, I had the telltale sign of a core leak the other day on my M1009 when I noticed some coolant on the passenger floor board. I disconnected the coolant lines to the heater core and connected them together for a temp fix until I can replace the core. My coolant levels are fine and no leaks noted. However, since the moment I bypassed the heater core my LOW COOLANT light remains on steady. ANy one have any ideas about this? I read somewhere somebody mentioned burping the system, how do you do that? M1009 runs fine and does not overheat but I'd like to alleviate this issue with the light. Thanks.

 

[dependable]

Low coolant light just went on in one of my 1008s for no reason. Good fluid level, no leaks. I suspect the low coolant module under the dash or the sensor itself. Will check it out when not so busy.

 

[ralbelt]

Clean the wire connection at the sensor on the radiator. Its possible it got loose when moving the hoses. I ran my M1008 for almost a year with the core bypassed. Finally found a local shop that has some NOS core stock and replaced it.

 

[Barrman]

Page 2-69 of the -20 manual says to ground the black/yellow wire at the sensor on the radiator with the key on. If the light goes out the sensor is bad. If the light stays on then you have to test the module.

I have 3 of these trucks and 2 of htem have had bad sensors. Ground the wire and see what happens.

 

[primalnick]

ralbelt got it! I should have checked it more than a visual glance. The connection at the sensor was not seated completely. At a glance it looked good, but I removed it and reseated it and now its good to go. Thanks for the assistance.