Clutch Volumes

CLUTCH VOLUMES

THEORY OF OPERATION
The volumes of the transmission fluid needed to apply the friction elements are continuously monitored and learned for adaptive controls. As the clutch friction material wears, the volume of fluid needed to apply the clutch increases. The following are typical clutch volumes, the clutches may be damaged if the volumes are greater or less than the specified below:

The LR clutch volume is updated when doing a 2-1 or 3-1 coast down shift. The transmission temperature must be between 21-49 °C (70-120 °F). The clutch volume should be between 35 and 83.

The 2/4 clutch volume is updated when doing a 1-2 shift. The transmission temperature must be above 43 °C (110 °F). The clutch volume should be between 20 and 77.

The OD clutch volume is updated when doing a 2-3 shift. The transmission temperature must be above 43 °C (110 °F). The clutch volume should be between 40 and 150.

The UD clutch volume is updated when doing a 4-3 or 4-2 shift. The transmission temperature must be above 43 °C (110 °F). The clutch volume should be between 24 and 70.

TRANSMISSION EFFECTS
These CVIs that are out of range are usually set with other DTC's, which indicates an internal transmission problem.

POSSIBLE CAUSES
- Clutch pack clearance out of spec
- Snap ring out of position or broken > Broken return spring
- Hydraulic leak into clutch circuit with near-zero volume

EATX DTC EVENT DATA
EATX DTC EVENT DATA can be used as a diagnostic aid when experiencing Electronic transmissions with intermittent problems. When a Diagnostic Trouble Code (DTC) is set, the vehicles transmission inputs are stored in the controller memory and are retrievable with the DRB III. This information can be helpful when a DTC can not be duplicated.

The EATX DTC EVENT DATA is located in the DRB III, under the Transmission system menu, in the sub-screen Miscellaneous. It is a good practice to document the EATX DTC EVENT DATA before beginning any diagnostic or service procedure.

A thorough understanding of how the transmission works is beneficial in order to interpret the data correctly. These skills are necessary in order to avoid an incorrect diagnosis.

A MASTERTECH video and reference book was produced in January 2002 that explains many of the features of the EATX DTC EVENT DATA with several examples on how to interpret the information and suggested training material to help understand all the specifics.

EATX DTC EVENT DATA can only be erased by:
1. Disconnecting the battery.
2. Performing a DRB III QUICK LEARN procedure.
3. Reprogramming the NGC/EATX controller.

NOTE: Erasing Transmission DTCs does not clear the EATX DTC EVENT DATA.