4L30E Pressure Control Solenoid 1990, new and ready to install. Fits the 4L30E. Ships fast from the USA.
The 1990 model year was the first for the 4L30E four-speed automatic, and in North America it showed up behind two very different engines: the Isuzu Trooper V6 and the BMW E34 525i inline-six. If a 1990 Trooper or 525i now slams into drive, shifts late and mushy once it is warm, or sits in one gear with a warning light, the pressure control solenoid (GM calls it a force motor) is a prime suspect. This listing is a new 1990 4L30E force motor. As the photo shows, it is the version with a silver metal can and a white plastic connector shroud on the end, which is how you tell it apart from the later black-bodied parts with two exposed spade terminals.
GM's own 4L30-E spec sheet lists the control hardware plainly: two 3-way on-off solenoids pick the gear, a single force motor handles shift quality, a 2-way on-off solenoid applies the converter clutch, and a separate high-flow PWM solenoid is used only for 3-2 downshifts. There is no throttle cable, so the force motor is the only way the control unit can raise or lower line pressure. It is a variable solenoid: the computer changes the current through the coil, the spool on the nose moves, and the signal oil it sends to the pressure regulator sets main line pressure for every clutch and band. The same spec sheet lists adaptive pressure control and temperature compensation, which all depend on this part responding accurately. When the coil weakens or the spool drags in its bore, the computer keeps commanding pressure but the transmission stops obeying.
Check the fluid first. Dark, burnt fluid with friction material in the pan means slipping has already damaged clutches or a band, and a new force motor will not undo that. Next, pull the codes with a reader that understands the 1990 Isuzu or BMW system, then test the force motor circuit at the transmission connector for correct resistance and for a short to ground; our multimeter solenoid test guide covers the meter work. A coil that measures fine can still have a stuck spool, so the strongest test is a gauge on the line pressure tap, which GM lists as a standard port on this unit. Our line pressure guide explains how to read it. If the force motor tests good and the shift is still bad, wear in the valve body bores is the next place to look.
This part is listed for the 1990 4L30E. Applications that year include the 1990 Isuzu Trooper and the 1990 BMW E34 525i (the 518i outside North America used it as well). The Isuzu units use a lower first and second gear ratio than the BMW units, and the adapter case and wiring differ between automakers, but the force motor sits in the valve body that both share. Because this was the launch year and the part changed in later years, match the body, the white connector shroud and the spool nose against your old force motor before installing, or send us your year and VIN and we will check it for you. Later trucks need a different part: see the 1994-1998 4L30E pressure control solenoid. For other 4L30E hard parts, browse our transmission hard parts.
| Fits | 4L30E 1990 |
| Part type | Pressure Control Solenoid |
| Condition | New |
| Brand | OEM |
| Ships | From the USA |
| Warranty | 1-year |
It is listed for the 1990 4L30E, which both vehicles used. The force motor lives in the valve body, but wiring and some case parts differ by automaker, so compare your old part's body, white connector shroud and nose with the photo, or send us your year and VIN.
1990 vehicles are pre-OBD-II. The 1990-93 Trooper and Rodeo store Isuzu-specific shift solenoid, band-apply and ground-circuit codes, and the BMW uses its own system, so you need a reader for that system rather than a generic OBD-II scanner.
It changes line pressure. High pressure gives harsh engagements and firm shifts; low pressure gives slipping and flares. A sticking spool can also trigger the limp-home mode with a fixed gear and a warning light.
No. The 1990 part shown here has a silver metal can and a white connector shroud. Later 4L30E force motors use a black body with exposed spade terminals and are sold as separate listings.
GM's 4L30-E specification sheet lists Dexron III. BMW also published its own fluid approvals, so follow your owner's manual if it lists something different, and check the level with the fluid hot.
At least the filter and pan gasket. On a transmission this old the shift and converter clutch solenoids are usually original, so replacing them during the same pan drop saves doing the job twice.
