Engine Coolant Temp Sensor Description; Operation; Removal; Installation - Chrysler PT Cruiser Service & Repair Manual

7 - 20 ENGINE - 1.6L SOHC
ENGINE BLOCK HEATER (Continued)
Fig. 11 Engine Block Heater
1 - BLOCK HEATER
2 - SCREW
ENGINE COOLANT TEMP
SENSOR
DESCRIPTION
The engine coolant temperature (ECT) sensor
threads into the rear of the cylinder head, below the
thermostat housing (Fig. 12). New sensors have seal-
ant applied to the threads. The ECT Sensor is a Neg-
ative Thermal Coefficient (NTC) sensor.

OPERATION

The ECT sensor provides an input to the PCM. As
temperature increases, resistance of the sensor
decreases. As coolant temperature varies, the ECT
sensor resistance changes resulting in a different
voltage value at the PCM ECT sensor signal circuit.
The ECT sensor provides input for various PCM
operations. The PCM uses the input to control air-
fuel mixture, timing, and radiator fan on/off times.
The ECT sensor input is also used for temperature
gauge operation.

REMOVAL

(1) Disconnect negative battery cable.
(2) Disconnect positive battery cable.
(3) Remove battery.
(4) Partially drain cooling system.
(5) Disconnect coolant temperature sensor electri-
cal connector.
(6) Remove coolant temperature sensor (Fig. 12).
Fig. 12 Engine Coolant Temperature Sensor
1 - ENGINE COOLANT TEMPERATURE SENSOR

INSTALLATION

(1) Install coolant temperature sensor (Fig. 12).
Tighten sensor to 17 N·m (150 in. lbs.).
(2) Reconnect coolant temperature sensor connec-
tor.
(3) Install battery.
(4) Connect positive battery cable.
(5) Connect negative battery cable.
(6) Fill cooling system (Refer to 7 - COOLING/EN-
GINE - STANDARD PROCEDURE).
ENGINE COOLANT
THERMOSTAT AND HOUSING
REMOVAL
(1) Disconnect negative battery cable.
(2) Disconnect positive battery cable.
(3) Remove battery.
(4) Partially drain cooling system.
(5) Remove fasteners securing heater return tube
to engine block and thermostat housing. Reposition
heater tube.
(6) Disconnect upper radiator hose and heater hose
from thermostat housing.
(7) Remove thermostat housing fasteners (Fig. 13).
INSTALLATION
(1) Clean all sealing surfaces.
(2) Place thermostat and seal into thermostat
housing. Align air bleed with notch in thermostat
housing (Fig. 14).
PT