A/T - Production Changes Improve Shift Feel

Bulletin No. T 85-102
File in Group 7
Number 125
Corp. Ref. No. 8057609
Date Aug. '85

SUBJECT: THM 440-T4 TRANSAXLE SERVICE PARTS AND UNIT REPAIR INFORMATION

MODELS AFFECTED: ALL 1985 FWD DEVILLE/FLEETWOOD MODELS (EQUIPPED WITH GAS ENGINE)

Effective with VIN broadcast number 314311, gas engine equipped 1985 FWD De Villes and Fleetwoods have been released with both a later model THM 440-T4 automatic transaxle and ECM PROM calibration to improve shift feel and pleasability. As a result, the specific parts and service information contained in this bulletin must be utilized when performing transaxle service on these vehicles.

EARLY TRANSAXLE MODEL . . .replaced by . . . .LATER TRANSAXLE MODEL


AC . . . . . . . . . . . . . . .(Limousine). . . . . . . . . . . . . . AF AY . . . . . . . . . . . . . (FED & CAL) . . . . . . . . . . . . . .AM

Models OY and OB for diesel applications are not affected by this change.

Parts Information:

FIGURE 1 - TRANSAXLE MODEL IDENTIFICATION NAMEPLATE INFORMATION:

The hydraulic circuits in the control valve assembly, channel plate, spacer plate have been redesigned in later model units. As a result, these components are not interchangeable. When servicing the transaxle, check the I.D. nameplate (refer to Figure 1) to determine the transaxle model year and type. GMWDD catalogues (printed after June, 1985) utilize this number (e.g., 5AY or 5AM) to distinguish early and late components.

Although the listed components CANNOT be interchanged between early and late transaxle models, complete transaxle assemblies can be interchanged. Later model assemblies (AM/AF) are to be utilized when transaxle assembly exchange is required.

When an early model THM 440-T4 is replaced with a later model, install a later calibration ECM PROM. Refer to the following PROM information to ensure correct application.

TRANS
MODEL EMISSIONS TYPE PART NUMBER PROM I.D. BROADCAST CODE

AF, AM Federal 16052276 215 HMC
AF, AM California 16052282 226 HMD

Repair Information:

FIGURE 2 CHECK BALL LOCATIONSCONTROL VALVE ASSEMBLY:

FIGURE 3 CHECK BALL LOCATIONSCHANNEL PLATE:

The current 1985 Service Information Manual describes early models and will provide enough reference material when performing dealer authorized repairs for both early and late models (for details concerning dealer authorized repairs refer to Serviceman Bulletin T-85-77). The exception is check ball locations. Refer to Figure 2 for control valve assembly and Figure 3 for channel plate check ball locations for the later transaxles (AM/AF). Note the position and size of check ball #5 has been changed from that of early models.