AT Oil Temp Light On, DTC 15 Set (Adjust Automatic Transmission Fluid to Correct Level)

Some customers may comment that the "AT OIL TEMP" light is illuminated. Upon investigation, the technician may find DTC 15 set. There may also be evidence of fluid leakage at the end of the breather tube.

Automatic Transmission (AT) fluid being overfilled may cause this condition. Continued vehicle operation in this condition may cause the transmission to overheat and cause subsequent damage.

Adjust the AT fluid to the correct level following the procedure below.

Important: With the AISIN transmission, it has been determined that accurate fluid level can only be judged when the transmission is at an operating temperature between 70°C (158°F) and 80°C (176°F).

1. Connect the Tech 2® scan tool to the vehicle and operate the vehicle until the fluid temperature reads between 70°C (158°F) and 80°C (176°F).
2. Park the vehicle and firmly set the parking brake.
3. With the engine running, and brake pedal depressed, cycle the transmission shifter from "P" all the way down to "1" a few times in order to distribute the fluid through the transmission hydraulic circuits.
4. Place the transmission in "Park."
5. Verify that the fluid temperature reads between 70°C (158°F) and 80°C (176°F) on the Tech 2® scan tool.
6. Pull the indicator (dipstick) and inspect if the fluid level is within the Hot "H" range (while engine is running at idle). Adjust as needed.

Please observe the initial fill minimum requirements for AT service and/or replacement on the chart below. "C" (Cold) range on the indicator should be used for reference at initial fill only.

Maintaining proper fluid level would be considered a truck owner responsibility and any procedure performed to correct an overfill condition is not a warranty repair.