TM-9-2320-280-20 HMMWV Technical Manual Unit Maintenance Volume 1 Download
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TM 9-2320-280-20-1 TRANSMISSION SYSTEM (4L80-E) DTC 73 Pressure Control Solenoid (PCS) Circuit Current Error (Force Motor Circuit) Circuit Description: The pressure control solenoid is a TCM-controlled device used to regulate transmission line pressure. The TCM compares TP voltage, engine rpm and other inputs to determine the appropriate line pressure of a given load. The TCM will regulate the pressure by applying a varying amperage to the pressure control solenoid. The applied amperage can vary from 0.1 to 1.1 amp. The TCM then monitors the amperage at the return line. DTC 73 Will Set When: . The return amperage varies greater than 0.16 amps from the commanded amperage. . All conditions are met for 1 second. DTC 74 Transmission Input Speed Sensor (TISS) Circuit Circuit Description: The TISS sensor consists of a permanent magnet surrounded by a coil of wire. As the forward clutch housing rotates, an AC voltage is induced in the circuit. The signal voltage and frequency vary directly with the forward clutch rotational speed. DTC 74 Will Set When” s Trans range not in park or neutral. . Engine speed greater than 300 rpm. ● Trans output speed greater than 200 rpm. ● Trans input speed less than 50 rpm. . All conditions are met for 2 seconds. DTC 75 System Voltage Low Circuit Description: Ignition voltage is supplied to the control module to indicate the status of the ignition switch. Battery voltage is supplied to the control module to, in part, maintain memory of learned functions and parameters. DTC 75 Will Set When: ● The ignition is “ON.” ● Ignition feed voltage to the control module is less than the graduated scale of: . -40°F (-40°C) = 7.3 volts. - 194°F (-90°C) = 10.3 volts. - 302°F (-150°C) = 11.7 volts. ● Engine speed greater than 1000 rpm. ● All conditions are met for 4 seconds. DTC 79 Transmission Fluid Overtemp Circuit Description: The Transmission Fluid Temperature (TFT) sensor is a thermistor that controls the signal voltage to the TCM. The TCM supplies a 5-volt reference signal to the sensor on CKT 923A. When the transmission fluid is cold, the sensor resistance is high and the TCM will sense high signal voltage. As the transmission fluid temperature warms to normal transmission operating temperature 212°F (100°C), the sensor resistance becomes less and the voltage decreases to approximately 1.5 to 2.0 volts. DTC 79 Will Set When: ● Trans fluid temp greater than 295°F (146°C). ● All conditions are met for 30 minutes. 2-425