DIESEL HIGH OR LATE UPSHIFT NEW VRV /400 TRANSMISSION

MODELS: 1982 "C-K-P" WITH 6.2L AND 400 AUTOMATIC TRANSMISSION

Comments regarding high or late upshifts in 1982 "C-K-P" trucks equipped with 6.2L diesel engines and THM 400 automatic transmissions may be the result of the vacuum regulator valve (VRV) calibration. This condition may be cor- rected by replacing the valve with a new valve, P/N 14057219.

The new valve entered production at the assembly plants in March, 1982.

The VRV should be verified as the cause of this condition using the following procedure:

1. Identify which valve (old or new) is on the engine. Refer to Figure No. 1.

a. Old valve - rotating CAM is green color. P/N 14033982 is cast into the valve.

b. New valve - rotating CAM is orange color. P/N 14057219 is white lettered on face of valve.

2. If the valve has a green rotating CAM, remove the valve. If the rotating CAM is orange, go to Step 5.

3. Install a new valve. P/N 14057219.

4. Follow Service Manual procedures (6C6-2)- but set the valve to 27 KPA.

5. If the valve has an orange rotating CAM (P/N 14057219), check for a correct setting of 27 KPA using Service Manual Procedures.

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.