SERVICE MANUAL UPDATE THM 440-T4 DIAGNOSIS/REPAIR

MODELS AFFECTED: 1986-1987 DE VILLES, FLEETWOODS, ELDORADOS, AND SEVILLES

This bulletin is provided to update information contained in the 1986 440-T4 Automatic Transaxle unit repair section and the 1987 440-T4 Automatic Transaxle Hydraulic Diagnosis and Unit Repair Sections of the Service Information Manuals. Please update your 1986 and 1987 Service Information Manuals with the revisions provided in this Bulletin (refer to the chart below).

NOTE: When checking line pressure on a 1987 THM 440-T4 transaxle, it is important to follow the steps as described in the Preliminary Check Procedure in Figure 2. Using the TV cable to check maximum line pressures WILL NOT provide the accurate readings referenced in the range pressure chart. Since the introduction of the aneroid vacuum modulator, detente oil seats the #14 check ball against modulator pressure and then becomes effective on the line boost valve, in place of modulator pressure.

REVISED SERVICE MANUAL INFORMATION

BULLETIN FIGURE MODEL YEAR SECTION PAGE FIGURE NUMBER NUMBER

1 1986 7Al-Transaxle Unit Repair 440 T4-5 4

2 1987 7A-Hydraulic Diagnosis 440-T4-4 3

3 1987 7Al-Transaxle Unit Repair 440-T4-14 34

4 1987 7A-Hydraulic Diagnosis 440-T4-3 2

5 1986 7Al-Transaxle Unit Repair 440-T4-69 79

5 1987 7Al-Transaxle Unit Repair 440-T4-52 79

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.