Century Estate Wagon V6-231 3.8L VIN 3 FI (1987)
Accumulator: All Technical Service Bulletins
A/T - THM 440-T4 Harsh or Firm 2-3 Upshifts.
Bulletin 87-7440-18
Date April '89
Ref. No. 87-237-7440
Corp. Ref. No. 977108
SUBJECT:
HARSH OR FIRM 2-3 UPSHIFTS
MODELS AFFECTED:
1986 SRTA UNITS, AND 1987 CENTURYS, LESABRES, ELECTRAS, AND RIVIERAS EQUIPPED WITH A THM
440-T4 HYDRA-MATIC 4T60 TRANSAXLE AND 3.8L ENGINE (VIN CODE 3)
Figure 1 - THM 440-T4 Transaxle Identification Information
BULLETIN COVERS: (Figure 1)
A harsh or firm 2-3 upshift that may occur most noticeably under 1/2 throttle acceleration on 1986 SRTA models and 1987 Centurys, Electras, Rivieras,
and LeSabres equipped with a 3.8L and THM 440-T4/Hydra-matic 4T60 transaxle. This condition can be corrected by following the procedure listed
under "Service Action".
Figure 2 - 3-4 MTV And 2-3 Accumulator Valve Trains
SERVICE ACTION:
1.
Verify correct minimum and maximum pressures.
2.
Check for vacuum leaks and/or a low vacuum supply to the vacuum modulator. Required vacuum is 44-61 KPa (13-18 in. Hg.). The vacuum signal
