Low Coolant GM VEHICLES WITH A RECURRING “LOW COOLANT LIGHT” You may have trouble on some GM vehicles with a recurring “Low Coolant” light. The systems that we are referring are those that use a 3 wire coolant level sensor. The first order of business is to make sure that the coolant level in the system is correct. It would also be a good practice to make sure that the wiring harness is not damaged, or has been damaged and in the process of being repaired was incorrectly wired. What usually happens in these situations is the tech changes the coolant level sensor. This corrects the problem for a period of time, then the problem returns. If this is your situation then the problem may be contamination in the cooling system. Certain additives such as sealers or left over engine oil from those 3.1 or 3.4 liter intake gasket leaks can coat the end of the sensor and prevent it from reading properly. Next time you come across this problem, try removing the sensor and cleaning it with a wire brush or emery cloth. Rinse off any residue with brake cleaner. The probe tip should be shiny. Reinstall the sensor and see if it now works properly. Make sure the cooling system is free of any remaining contamination that may cause a recurrence. It would also be a good practice to make sure that the vehicle has the correct coolant/water mix. Visit our Resource Library for available downloads