HARSH 3-2 PART THROTTLE SHIFT AT 23-25 MPH/HIGH TEMP

MODELS AFFECTED: 1987-1988 ALLANTES

Some 1987-1988 Allantes may experience a harsh or firm 3-2 part throttle downshift when driven at 23-25 mph in high ambient temperatures. This may be caused by a poorly running engine, misadjusted TV cable, vacuum leaks, and/or a low vacuum supply to the vacuum modulator. If none of the above causes are found, a revised 3-2 control spring, available from the Cadillac Technical Assistance System (CAD-STAR), may be installed to repair the condition.

Service Procedure:

1. Check for poor running engine caused by plugged or clogged fuel injectors.

2. Check TV cable adjustment.

3. Verify correct minimum and maximum line pressures.

4. Check for vacuum leaks and/or a low vacuum supply to the vacuum modulator. Required vacuum is 55-61 kPa (13-18 in. Hg.). The vacuum signal should respond quickly to throttle movement. If not, check for restrictions such as paint in the modulator tube or carbon at the throttle body fitting.

5. If corrective action on any of the above steps does not resolve the condition:

Remove the valve body assembly.

Remove the 3-2 TV bias retainer (397), the 3-2 TV bias bushing (393), and the 3-2 control spring (341) as shown in Figure 1.

Replace the 3-2 control spring with one available from the Cadillac Technical Assistance System. Contact the Cadillac Technical Assistance System (1-800-CAD-STAR) to order a service package containing a 3-2 control spring, spacer plate gaskets, and an instruction sheet. A new side cover gasket kit, P/N 8644902, is also required. This kit is currently available from GMSPO.

IMPORTANT: ALL SERVICE REPLACEMENT TRANSMISSION ASSEMBLY (SRTA) UNITS BUILT AS OF JULIAN DATE 060 (1989) ARE EQUIPPED WITH THE REVISED 3-2 CONTROL SPRING.

Service Manual Reference:

Refer to Sections 7A1 and page F-7-41 of the THM F-7 (ME9) Automatic Transaxle Unit Repair Section in the 1988 Final Allante Service Information Manual

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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.