A/T - THM 400 Too Sensitive 3-2 Downshift
TSB 87-63 (Nov)THM 400
PROBLEM: Too sensitive 3-2 downshift
SOLUTION: Remove 3-2 Control Valve Spring
Before removing the 3-2 control valve spring, be sure the problem is not engine vacuum related, or electrical. By removing the 3-2 control valve spring, all part throttle downshifts will be eliminated; passing gear will only occur with detent, or full throttle downshifts.
The figure indicates the spring to be removed.