Seville V8-273 4.5L (1989)
Shift Modulator: All Technical Service Bulletins
A/T - 4T-60 1-2 Shift Problems
Bulletin No.
T-91-10
File in Group
7
Number
226
Corp. Ref. No.
077113R
Date
Oct. 1990
SUBJECT:
NO SECOND GEAR, SLIPS IN SECOND GEAR, SLIPS OR SHUDDERS DURING 1-2 SHIFT - 4T60
TRANSAXLE
MODELS AFFECTED:
1985-1990 DE VILLES AND FLEETWOODS 1986-1990 ELDORADOS AND SEVILLES
Some 1985-1990 DeVilles and Fleetwoods and 1986-1990 Eldorados and Sevilles equipped with a Hydra-Matic 4T60 transaxle may exhibit one of the
following conditions:
1.
Slips or shudders during 1-2 shift.
2.
Slips in second gear.
3.
No second gear.
This may be caused by a worn or damaged second clutch. When diagnosing a transaxle for one of the above conditions, the following items should be
checked first:
1.
Test drive the vehicle to verify the condition.
2.
Verify proper fluid level.
3.
Verify proper transmission line pressure according to the chassis service manual procedure. Check minimum pressure by applying 18" of vacuum
to the vacuum modulator (use a hand vacuum pump). Check maximum line pressure with no vacuum applied to the vacuum modulator (vacuum
line disconnected. Check both minimum and maximum at 1250 rpm in each range. If there is no boost in pressure with zero vacuum, check for an
inoperative vacuum modulator or modulator valve. A ruptured aneroid bellows in a vacuum modulator will result in no boost in pressure with zero
vacuum applied.
NOTE:
Do not measure maximum pressure by pulling out on the TV cable. 1987 and later models will give you a boosted pressure at full
TV which is not the same as the maximum pressure reading with zero vacuum. Using the TV cable can give you a false maximum
pressure reading and will not reveal an inoperative vacuum modulator.
Figure 1 - Vacuum Modulator
3a. Check vacuum modulator. Tools required: J-36619 for 1985-1986 models and J-35258 for 1987-1990 models. Refer to Figure 1.
^
Install a known good modulator of the same type on one side of the comparison gage.
^
Install the modulator to be tested on the other side of the gage.
-
If the gage line remains blue, the test modulator is not acceptable.
-
If the gage line is white, the modulator is acceptable.
