4L85E Pressure Control Solenoid, new and ready to install. Fits the 4L85E. Ships fast from the USA.
This is a new pressure control solenoid, listed under reference D34435B, for the GM 4L85E heavy-duty four-speed found behind the 8.1L and 6.0L engines in Chevrolet and GMC 2500/3500 pickups, Express and Savana vans and chassis-cab work trucks. Owners usually start looking for one when a loaded truck flares between gears, slips on the 1-2 when pulling a trailer, bangs into Drive from Park, or sets a pressure control code such as P0748 or P0960.
Every clutch and band in a 4L85E is applied with main line pressure, and the computer sets that pressure through this one part. GM calls it the pressure control solenoid (PCS); you will also see it called the EPC solenoid or force motor. It is a variable-current solenoid fed regulated oil by the actuator feed limit (AFL) valve. Its output oil acts on the boost valve at the pressure regulator, so it decides how hard the pump pushes on everything. The control is inverted: high current means low pressure. Published GM values show roughly 0.9 to 1.1 amps of command at idle and light load, falling toward 0.2 to 0 amps at wide open throttle just before the 1-2 shift, when the transmission needs the most holding power. A solenoid that cannot follow that command leaves the clutches either under-squeezed (slip, burnt frictions) or over-squeezed (harsh engagements and shift bang).
The 4L85E has no line pressure sensor, so the pressure number on a scan tool is the command, not a reading. Put an amp clamp on the PCS wire and a gauge on the line pressure tap, then compare the two at idle and at stall or wide open throttle. If the current command is right but the gauge does not follow, the solenoid or its feed oil is the problem. If the command itself is wrong, look at engine load data and the throttle or pedal signal first. Our 4L85E line pressure testing guide walks through the full procedure and what each result means. Also check the AFL valve: Sonnax documents that a worn AFL bore starves or floods every solenoid in the unit, and a new PCS will not cure that. The 4L85E valve body testing guide covers how to tell.
This listing fits the 4L85E and carries reference D34435B; it is the full-range listing rather than one tied to a single model year. The 4L85E shares its valve body and solenoid layout with the 4L80E, which is why solenoid service data for the two is published together, but pressure control solenoids have changed in connector and calibration over the years. Before ordering, compare the connector shape and the stamped number on your old solenoid to the photos, or send us your year and VIN and we will check it. If you have a 2004 truck specifically, also look at our 2004 4L85E pressure control solenoid. Browse every part for this unit on the 4L85E collection page.
| Fits | 4L85E |
| Part type | Pressure Control Solenoid |
| Condition | New |
| Brand | OEM |
| Reference | D34435B |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Yes. GM's service information calls it the pressure control solenoid, and many shops call it the EPC solenoid or force motor. It is the variable-current solenoid that sets line pressure, not one of the two on-off shift solenoids.
Only if line pressure is low because of the solenoid. Check commanded current against a pressure gauge first. If pressure is correct and it still slips, the clutches are worn and the unit needs rebuild parts, not a solenoid.
P0748 for a pressure control solenoid electrical fault and P0960 for an open control circuit are the common ones. Check the harness and case connector before replacing the part, since wiring causes the same codes.
GM specifies Dexron VI for the 4L85E. Refill to the correct hot level after the pan is back on, then verify pressure and shift quality on a road test.
The 4L80E and 4L85E share the valve body and solenoid layout, but connector style and part number changed across years. Match the connector and stamped number on your old solenoid, or send your year and VIN before ordering.
