Circuit Description
The coolant level sensor monitors the coolant level within the coolant system and passes
information to the electronic control module (ECM) through the engine harness. Because this sensor is so complex, do not use a multimeter to check it. If the radiator coolant level drops below a certain level, a progressive power and/or speed derate will occur. Engine can,
perhaps, shut down if engine protection shutdown feature is enabled.

Component Location
The coolant level sensor is located in the radiator top tank or surge tank.

Shop Talk
This is an OEM supplied component and can vary in location.
1) If a shorting plug is used in the coolant level circuit, verify that it is wired correctly.
2) Make sure the coolant level sensor is located in the middle of the tank rather than off to
one side where the coolant level can change when the vehicle turns toward a corner.
3) Make sure the correct ECM code is in the ECM. Calibrating the ECM with the incorrect
DO option can cause Fault Code 235 to be active since some OEMs use different
sensors that require special calibrations.
4) Sterling Trucks utilize ECM pin A22 for coolant level sensing through a 2-pin sensor.