Solenoid valve ST, for system pressure
| Solenoid valve ST, for system pressure |
Solenoid valve ST is located in the valve housing, which is mounted on the transmission casing. The solenoid regulates the automatic transmission's system pressure.
The solenoid is controlled by a 300 Hz PWM signal via control module pin 17 and is grounded via pin 18. It is controlled by the varying current that is the result of the prevailing pulse ratio. When the pulse ratio is high, i.e. high current strength (approx. 1 A), system pressure is low and when the pulse ratio is low, i.e. low current strength, system pressure is high. In the event of an open circuit, system pressure will be at maximum. The valve is then fully open.
The control module uses bus information on the current “Engine torque”, unit Nm, and the gear currently engaged to control system pressure.
The resistance of the winding in the solenoid is approx. 4 Ohm.
At idling speed, with the handbrake applied and the selector lever in position D, curr ent strength is approx. 900 mA and system pressure 3.4-4.6 bar.
Diagnostics
In the event of a fault in the solenoid, diagnostic trouble code P0748 will be generated and the transmission will go into Limp-Home mode.This project is supported by memberships and donations. If you use this site, please consider Joining SCNA and/or making a donation.
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