Test NF-4A - Checking Coolant & Throttle Position Sensor Calibrations

NOTE: For connector terminal identification, see CONNECTOR IDENTIFICATION. For appropriate wiring diagram, see WIRING DIAGRAMS at end of article.

Start engine. Allow engine to reach normal operating temperature. Using DRB-II, read coolant temperature sensor value. If coolant temperature sensor value is not 180-220°F (82-104°C), replace coolant temperature sensor. Perform VERIFICATION PROCEDURE VER-2.
If temperature is 180-220°F (82-104°C), turn engine off. Turn ignition switch to ON position. Using DRB-II, read Throttle Position Sensor (TPS) voltage with throttle fully closed and against throttle stop. If voltage is not 1.5 volts or less with throttle closed, replace TPS. Perform VERIFICATION PROCEDURE VER-2.
If voltage is 1.5 volts or less with throttle fully closed, monitor voltage while slowly opening throttle wide open. If voltage change is not a smooth transition, replace TPS. Perform VERIFICATION PROCEDURE VER-2.
If voltage change is a smooth transition, check if maximum voltage is at least 3.4 volts with throttle wide open. If maximum voltage is not at least 3.4 volts with throttle wide open, replace TPS. Perform VERIFICATION PROCEDURE VER-2.
If maximum voltage is at least 3.4 volts, start engine, and let it idle. Using DRB-II, read minimum throttle voltage. If voltage is not 0-1.5 volts, replace TPS. Perform VERIFICATION PROCEDURE VER-2. If voltage is 0-1.5 volts, test is complete.