B2300 SE Regular Cab 2WD L4-2.3L VIN A (1997)
Thermostat: Testing and Inspection
ELECTRICAL
NOTE: This test should be performed at temperatures less than 37.8° C (100° F) ambient air.
1. Hook up the New Generation Star (NGS) tester.
NOTE: For an accurate test reading the engine cooling fan must be running.
2. Make sure A/C switch is in OFF position.
3. Place the vehicle in Park (P) or Neutral (N).
4. Start the vehicle and allow the engine to run for 2 minutes.
5. Record the Engine Coolant Temperature (ECT) sensor voltage reading.
6. Record the ECT sensor voltage reading every 60 seconds.
7. When ECT voltage reverses direction or trend changes slightly (0.03 volt or less), thermostat has opened.
8. Refer to the chart for the voltage and corresponding temperature to verify thermostat operation.
Coolant Temperature / ECT PID Volts
21.7° C (71)° F / 3.00 V
42.8° C (109)° F / 2.01 V
70.6° C (159)° F / 1.01 V
82.2° C (180)° F / 0.75 V
90.6° C (195)° F / 059 V
96.7° C (206)° F / 0.50 V
105.1° C (221)° F / 0.40 V
(1) If the opening voltage is between 0.75 volts (82.2° C (1 80° F)) and 0.5 volts (90.6° C (1 95° F)), the thermostat is operating.
(2) If the opening voltage is not within this range, replace the thermostat.
MECHANICAL
1. Visually check that the thermostat valve is airtight.
2. Place the thermostat and a thermometer in water.
3. Heat the water and check the following.
Initial-opening temperature: 89° C (192° F)
Full-open temperature: 100° C (212° F)
Full-open lift: 3.2 mm (0.126 in) minimum
4. If the gasket surface of the thermostat is damaged, replace the thermostat.
