ON-CAR SERVICE W/AWD TRANS. EXCHANGE PROCEDURE

Models Affected: 1988-89 6000 STE AWD THM A-1/HYDRA-MATIC 3T40-A (MD9)

This bulletin has been revised to include 1989 model year and new transmission designator, THM A-11HYDRA-MATIC 3T40-A transmission.

BULLETIN COVERS:

On-car service and exchange procedure information regarding the THM A-l/HYDRA-MATIC 3T40-A transmission, which is a THM 125C/HYDRA-MATIC 3T40 equipped with an all-new transfer unit introduced in the 1988 Pontiac STE All Wheel Drive.

SERVICE ACTION:

All THM A-l/HYDRA-MATIC 3T40-A on-car service should be performed at the dealership. Presently the THM A-l/HYDRA-MATIC 3T40-A Transmission is on an exchange program until further notice.

Units requiring the removal of the Torque Converter, Transfer Unit and/or Transmission from the vehicle, are to be returned to Hydra-matic Division under terms of the THM A-l/HYDRA-MATIC 3T40-A Transmission Exchange Program.

SERVICE INFORMATION:

Transmission Identification Information Transmission Cooler Flushing On-Car Serviceable Components Preliminary Check and Transmission Exchange Procedure

Transmission Cooler Flushing:

Transmission cooler flushing must be performed whenever a THM A-1/ HYDRA-MATIC 3T40-A transmission is replaced. The cooler flushing tool, Kent-Moore number J35944, is an essential tool and must be used to properly flush the cooler and lines. Labor Time Guide Operation K7000, Transmission/Transaxle - Replace, includes time allowance for transmission cooler system flushing.

On-Car Serviceable Components: (Figures 2, 3, 4, 5, 6, 7 and 8) The following list of THM A-1 components, illustrated in Figure 3, can be serviced on-car by the dealer technician.

Transmission Cooler Flushing

Transmission cooler flushing must be performed whenever a THM A-1 transmission is replaced. The cooler flushing tool, Kent-Moore number J 35944, is an essential tool and must be used to properly flush the cooler and lines. Labor Time guide operation K7000, Transmission/Transaxle - Replace, includes time allowance for transmission cooler system flushing.

On-Car Serviceable Components (refer to Figures 4, 5 and 6)

The following list of THM A-1 components, illustrated in Figure 3 can be serviced on-car by the dealer technician.

SERVICE MANUAL REFERENCE:

This bulletin contains a Wiring Diagram (Figure 2), Line Pressure Chart and Shift Speed Chart which is not available in the 1988 Pontiac STE All Wheel Drive Service manual Supplement. Refer to the On-Car Service Section 7AI in the 1988 Pontiac STE All Wheel Drive Supplement whenever any on-car service is necessary.

Transmission Exchange Procedure:

Requests for a THM A-1/HYDRA-MATIC 3T40-A will be handled through the Pontiac Division's Technical Assistance System.

Pontiac Technical Assistance will establish a Case Number which will be forwarded to Hydra-matic for an exchange. Note: Oil Pressure readings must be taken before calling Pontiac Technical Assistance.

The information needed to obtain an exchange unit is as follows:

Date: V.I.N.

Dealer Name/Address/Phone Number Transmission Serial No.: Transmission Technician: Mileage:

Was the T.V. Cable Properly Adjusted? Yes No

Description of problem:

Oil Pressure Readings:

Minimum Line Pressure Full Line Pressure

D3 D2 D1 P,R,N

The dealership will be mailed an envelope containing the following:

Return shipping label Reporting form Leak identification charts Transmission Exchange Procedure Instructions Information Tag (to be wired to unit being returned)

Remove all plastic shipping plugs and covers from the exchange unit (new) and install them on the original assembly.

Repack the original transmission into the shipping container and place proper shipping label and information on container.

The Technical Assistance Consultant will need a detailed description of the transmission's condition (after a road test for operational transmissions).

Transmissions must be returned complete, as removed from the vehicle, without examination other than outlined in On-Car Service. Dealerships returning units that have been partially disassembled will be billed for all materials furnished for violating this exchange procedure.

PRELIMINARY CHECK PROCEDURE

CHECK TRANSMISSION OIL LEVEL - CHECK AND ADJUST T.V. CABLE CHECK OUTSIDE MANUAL LINKAGE AND CORRECT - CHECK ENGINE TUNE INSTALL OIL PRESSURE GAGE* - CONNECT TACHOMETER TO ENGINE CHECK OIL PRESSURES IN THE FOLLOWING MANNER:

Minimum T.V. Line Pressure Check -------------------------------- Set the T.V. cable to specification; and the brakes applied, take the line pressure readings in the ranges and at the engine r.p.m.'s indicated in the chart below.

Full T.V. Line Pressure Check ----------------------------- Full T.V. line pressure readings are obtained by tying or holding the T.V. cable to the full extent of its travel; and with the brakes applied, take the line pressure readings in the ranges and at the engine r.p.m.'s indicated in the chart below.

CAUTION:

Brakes must be applied at all times.

NOTICE: Total running time for this combination not to exceed 2 minutes.

MINIMUM T.V. MAXIMUM T.V. RANGE PBS MODEL kPa P.S.I. kPa P.S.I. ----- --------- ------------------- -------------------- Park @ 459-507 66-73 459-507 66-74 1000 RPM

Reverse @ 775-883 112-124 1926-2151 279-312 1000 RPM

Neutral/ 459-505 66-73 1143-1276 166-185 Drive @ 1000 RPM

Intermediate/ 1151-1267 167-184 1151-1267 167-184 Lo @ 1000 RPM

Line pressure is basically controlled by pump output and the pressure regulator valve. In addition, line pressure is boosted in Reverse. Intermediate and Lo by the reverse boost valve.

Also, in the Neutral, Drive and Reverse positions of the selector lever, the line pressure should increase with throttle opening because of the T.V. system. The T.V. system is controlled by the T.V. cable, the throttle lever and bracket assembly and the T.V. link, as well as the control valve pump assembly.

"THM A-1/HYDRA-MATIC 3T40-A" SHIFT SPEED CHART ---------------------------------------------- FINAL 1-2 MIN. 2-3 MIN. 3-2 COAST 3-2 COAST 3-2 COAST 2-1 MAN MODEL DRIVE THROTTLE THROTTLE THROTTLE DOWN DOWN LOW RATIO ------------------------------------------------------------------------------ PBS 2.84 9-12 20-21 43-50 18-20 6-10 43-49

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.