Seville V8-273 4.5L (1989)
Service Procedure:
A coast down bump is obtained by allowing the vehicle to coast down to 15-22 mph (with closed or zero throttle) and a sudden and forceful apply of the
1-2 band is felt when the transaxle shifts from third to second gear.
A harsh 3-2 coast down bump may be caused by the 1-2 servo cushion spring. Refer to Figure 7. This condition may be corrected replacing the 1-2 servo
cushion spring with the part listed below. Refer to the chart below to determine the transaxle model and Julian Date when the new springs were first used
in production units.
IMPORTANT:
The 9ACH, 9ADH and 9AHH models could also have a harsh park/neutral to drive engagement bump. The suspect units were built from March 17,
1989 (Julian Date 076) to May 4, 1989 (Julian Date 124) for these three models only.
P/N
Description
8668123
1-2 Servo Cushion Spring (559)
Parts are currently available from GMSPO.
If the above condition persists, make sure the 3-2 coast down valve (located in the oil pump body) is not stuck and moves freely in its bore.
Viii. Harsh Upshifts At High Altitude* Only
1985-1986 DeVilles and Fleetwoods and 1986 Eldorados and Sevilles
