Automatic Transmission Fluid Pumps

WARNING: This page is about a different variant/trim than selected.

Mechanical Automatic Transmission Fluid Pump

The mechanical ATF pump is an integral part of the transmission. The ATF pump is used to supply hydraulic pressure for the operation of the control valves and clutches, to pass the fluid through the transmission cooler and to lubricate the gears and shafts.

The mechanical ATF pump is a double stroke, vane type pump and is located below the transmission input shaft. The pump is driven by a chain drive from a sprocket located on the input shaft.

Electric Automatic Transmission Fluid Pump

A low voltage 12V electric ATF pump is located in the transmission, at the rear of the Mechatronic valve block.

The electric ATF pump is connected to the transmission hydraulic circuit and is controlled by the TCM . The pump has two electrical connections with the TCM :

A Pulse Width Modulated (PWM) connection for electric motor operation.
A diagnostic feedback and a ground.

The electric ATF pump provides pressure and flow to the transmission and the engine disconnect clutch when the vehicle is stationary. The electric ATF pump also provides pressure and flow and when driving in EV mode and the CIMG speed is slow.

The electric ATF pump can have two failure states:

The electric ATF pump's integral software can report back a permanent failure to the TCM .
The TCM can detect the loss of 'pump status' signal.

In both cases the TCM will send a request to run the CIMG to the PCM on the HS CAN powertrain systems bus. The request to run the CIMG which will rotate the transmission input shaft and operate the mechanical ATF pump.