Check Plug Method

WARNING: This page is about a different car, the 2016 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.

Remove the oil level check plug.
CAUTION: Use Dexron® HP transmission fluid only. Failure to use the proper fluid may result in transmission internal damage.

NOTE: When the oil level check plug is removed with the engine OFF, transmission fluid may drain from the hole.

Fig 1: Oil Level Check Plug
Courtesy of GENERAL MOTORS COMPANY
Install the DT-51190 fluid fill pan adapter (1) and, if necessary, one adapter from the DT 45096-30 cooler flush adapters (2).

Fig 2: Fluid Fill Pan Adapter
Courtesy of GENERAL MOTORS COMPANY
Determine the approximate amount of fluid needed to fill the transmission, based on the repair performed. Refer to Approximate Fluid Capacities. To avoid an under-fill condition, slightly overfill the transmission and then allow the extra fluid to drain out through the oil level check plug during the transmission fluid level and condition check procedure.
Using the DT-51190 fluid fill pan adapter (1), DT-45096-30 cooler flush adapters (2) and the DT-45096 flush and flow test tool (3), add transmission fluid through the check plug hole. Refer to Transmission Fluid Cooler Flushing and Flow Test for complete DT-45096 operating instructions. Use the FLOW position on the main function switch to pump the fluid.
NOTE: The DT-45096 flush and flow test tool is being utilized as a convenient method to pump the fluid into the bottom pan. A suitable hand pump may also be used instead. When using the DT-45096 flush and flow test tool, monitor the display panel to determine the amount of fluid being pumped from the tool supply tank into the transmission.
Start the engine and move the shift lever through each gear range. Pause for at least 3 seconds in each gear range.
NOTE: Failure to start the engine and move the shift lever through the gear ranges before removing the DT-51190 fluid fill pan adapter and DT-45096-30 cooler flush adapters from the bottom pan will result in an excess amount of fluid draining from the check plug hole. This may lead to an under-fill condition.
With the engine still running, remove the DT-51190 fluid fill pan adapter (1), (2) and DT-45096 flush and flow test tool (3) and then check the fluid level. Refer to Transmission Fluid Level and Condition Check
CAUTION: Check the transmission fluid level immediately after adding fluid and before vehicle operation. Do not overfill the transmission. An overfilled transmission may result in foaming or fluid to be expelled out the vent tube when the vehicle is operated. Overfilling will result in possible damage to the transmission.