Ford Coolant Temperature Sensor Replace With Diagrams

Ford F-350 Coolant Temperature Sensor

OPERATION

When coolant temperature is low, the resistance of the sending unit is high, restricting the flow of current through the gauge and moving the pointer only a short distance. As coolant temperature rises, the resistance of the sending unit decreases, causing a proportional increase in current flow through the sending unit and corresponding movement of the gauge pointer.

The sending unit may only be tested for operation. There is no calibration, adjustment or maintenance required.

TESTING

See Figures 1, 2, 3 and 4

Fig. Fig. 1: Coolant temperature sender location-4.9L engine

Fig. Fig. 2: Coolant temperature sending unit-5.0L/5.8L engine shown, 7.5L engine similar

Fig. Fig. 3: Submerge the end of the coolant temperature sensor in cold or hot water and check the resistance

Fig. Fig. 4: Coolant temperature sensor temperature vs. resistance values

1. Remove the sensor from the vehicle.
2. Immerse the tip of the sensor in container of water.
3. Connect a digital ohmmeter to the two terminals of the sensor.
4. Using a calibrated thermometer, compare the resistance of the sensor to the temperature of the water. Refer to the engine coolant sensor temperature vs. resistance illustration.
5. Repeat the test at two other temperature points, heating or cooling the water as necessary.
6. If the sensor does not meet specification, it must be replaced.

REMOVAL & INSTALLATION

For the location of your unit, see the accompanying illustrations.

1. Disconnect the negative battery cable.
2. Drain the cooling system into a suitable container.

CAUTION

When draining the coolant, keep in mind that cats and dogs are attracted by ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

3. Disengage the electrical connector at the temperature sender/switch.
4. Remove the temperature sender/switch.

To install:

5. Apply pipe sealant or Teflon® tape to the threads of the new sender/switch.
6. Install the temperature sender/switch and connect the electrical connector.
7. Connect the negative battery cable. Fill the cooling system.
8. Run the engine and check for leaks.