P0745: Altima line-pressure solenoid feedback and duty-cycle context

P0745 in the 2001 Nissan Altima automatic-transmission manual concerns the line-pressure solenoid circuit. The TCM detects an improper voltage drop when it attempts to operate the solenoid. That electrical result does not directly measure how much hydraulic pressure the transmission produced.

Interpret duty cycle under the correct throttle state

The solenoid regulates pump discharge pressure to suit driving conditions. Nissan warns that the displayed line-pressure duty value is not consistent while the closed-throttle switch is ON. A number observed at closed throttle should therefore not be compared uncritically with the low-pressure reference.

The documented references relate a smaller throttle opening to lower pressure demand and a larger opening to higher demand. They describe the intended control relationship, not a substitute for the circuit and hydraulic tests appropriate to a particular symptom.

Separate the circuit from the component

The listed possibilities are an open or short in the harness/connectors and the line-pressure solenoid. The wiring includes a dropping-resistor path, making the correct vehicle diagram important when interpreting measurements. A single voltage obtained from an unidentified terminal is insufficient evidence to condemn the TCM or valve.

After identifying and repairing the actual defect, use the manual's confirmation procedure. Its command conditions differ from simply letting the engine idle and checking whether the code has disappeared. Record the throttle-switch state, relevant control signal and circuit findings. Internal transmission inspection should follow the complete service procedure; the P0745 label alone does not justify a rebuild.

Documented application

2001 Nissan Altima, AT section. Exact engine, drivetrain and diagnostic applicability must be checked in the cited procedure.

Source

2001 Nissan Altima Factory Service Manual: AT, physical PDF pages 133, 134, 136, 137.