Water Pumps
1. Test using the controller’s indicator lights. Check the indicator light during the freeze cycle. The light
will be On for all but the 30 second anti-slush period, so observe the light for one minute. When it is On,
check the water pumps, both should be operating. If only one is operating check for voltage to that
pump, if there is no voltage, replace that pump.
One of the pumps will operate during the part of the drain cycle, when the purge valve light is on. If both
are off, check for voltage at the dump valve relay. The coil of that relay should have power when the
purge light is on, connecting power to one of the pumps. Check for voltage from the relay to the pump. If
there is voltage to the pump and it does not pump water, replace the pump. If there is no voltage at the
pump and the purge valve is working, replace the dump valve relay.
2. Test using an ohmmeter. Disconnect electrical power. Unplug the suspect water pump motor leads
from the harness. Measure the resistance of the motor windings. If open, replace the pump. Measure
resistance to ground. If there is any, replace the pump.
November 2010
Page 27
C2648 Service Manual
Test Procedures - Loads
Water pump light is ON when one or both
pumps are in operation.
Only one water pump is ON when the
purge valve light is ON.
