Line Pressure Control during Low Loading

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Both in D or Sunder low engine load condition after warming up the engine and in all ranges (P, R, N, D, or S) under the low oil temperature condition, the PCM operates line pressure solenoid valve A, and switches the line pressure to the pressure that is lower than normal. This operation can reduce the friction in the transmission.

Fig 1: Identifying Line Pressure Control During Low Loading

Courtesy of AMERICAN HONDA MOTOR CO., INC.

The PCM turns line pressure solenoid valve A on, and applies the hydraulic pressure to the PLA' cavity on the main regulator valve. When the hydraulic pressure is applied to the PLA' cavity, the main regulator valve is pushed to the spring side. This operation expands the drain port of the main regulator valve, and causes the line pressure to be lower than normal.

Fig 2: Line Pressure Control During Low Loading Operation Chart

Courtesy of AMERICAN HONDA MOTOR CO., INC.