Parking Lock System - Revised For Heavier (GVW) Vehicles
89Pontiac24Bulletin Number: 90-7-13
Reference Number: 977154
Publish Date: 11/89
Subject: NEW PARKING LOCK SYSTEM FOR HEAVIER GROSS VEHICLE WEIGHT (GVW) VEHICLES
Models
Affected: 1990 6000, BONNEVILLE AND GRAND PRIX MODELS WITH 4T60/440-T4
Figure 1 - Previous And New Actuator Guide:
Figure 2 - Previous And New Parking Lock Actuator Assembly:
Figure 3 - Previous And New Case Bore:
Figure 4 - Previous And New Parking Lock Pawl:
CHANGE TO ASSEMBLY COMPONENTS: (Figures 1 - 4)
To expand model usage that includes vehicles with a heavier Gross Vehicle Weight (GVW), a new parking lock system will be used in the production of all 1990 transaxle models for the 1990 6000, Bonneville and Grand Prix models equipped with a HYDRA-MATIC 4T60 (THM 440-T4). For this change to be implemented, the following parts were modified:
Figure 1 - Previous And New Actuator Guide:
- Actuator guide is now wider by 0.65 mm (0.026") for the increased thickness of the parking lock actuator assembly. The pawl lockout plunger assembly and spring are eliminated. Now, there is no need for a slot for the plunger to ride in; therefore, the slot has been eliminated. The O-ring (bushing/actuator guide) seal is now larger to accommodate the increased thickness of the actuator guide. (Figure 1)
Figure 2 - Previous And New Parking Lock Actuator Assembly:
The parking lock actuator assembly "bullet" is now 1.77 mm (0.070") wider. The overall length of the new assembly is now 13.8 mm (0.543") longer than the previous assembly. (Figure 2)
Figure 3 - Previous And New Case Bore:
- Transaxle case bore for the actuator guide is now wider by 0.65 mm (0.026") to accommodate the wider actuator guide. (Figure 3)
Figure 4 - Previous And New Parking Lock Pawl:
- The parking pawl lock-out pin has been eliminated from the final drive parking lock pawl and the effective length reduced about 1.0 mm (0.039") from bullet to parking gear because of the wider actuator "bullet". (Figure 4)
IMPORTANT:
The new parking lock system will not service past models, unless ALL the components are replaced including the transaxle case. The transaxle case, parking lock actuator assembly, parking lock pawl and actuator guide are not interchangeable with models built before September 25, 1989 (Julian Date 268).
DATE OF PRODUCTION CHANGE:
Starting September 25, 1989 (Julian Date 268) all HYDRA-MATIC 4T60 (THM 440-T4) are built with the new parking lock system.
SERVICE PROCEDURE:
The new parking lock system will assemble the same way as the previous parking lock system.
SERVICE PARTS INFORMATION:
Parts are expected to be available on 12-15-89. Until then, normal part orders will not be accepted by GMSPO. Only verifiable emergency VIP orders will be accepted. SPO will make every effort to obtain parts. All parts will be placed on 400 control to waive VIP surcharges. However, the part will be shipped premium transportation at dealer's expense. All other order types will be canceled as incorrectly ordered while the 400 control is in place.
SERVICE MANUAL REFERENCE:
Refer to the appropriate 1990 Service Information Manual for service procedures.