Some 2001 vehicles equipped with 4R100 transmission, having a transmission build date between 7/27/2000 and 3/23/2001, may exhibit an intermittent, delayed or no second gear condition. Diagnostic Trouble Codes (DTC's) that may be set with this concern are P0781 (1-2 shift error), P0755 (shift solenoid B malfunction) and P0756 (shift solenoid B performance). This may be caused by the Intermediate One Way Clutch (mechanical diode style) not operating properly.
Verify condition, follow normal diagnostics per the appropriate Workshop Manual. If diagnostics leads to the described condition, replace the Intermediate One Way Clutch (OWC) (mechanical diode style 7A089), Intermediate Brake Drum (7D044) and Intermediate Clutch internally splined friction plates (7B164). Refer to the following Service Procedure for details.
Verify above "ISSUE". Refer to Figure 1 for replacement components. Refer to the appropriate Workshop Manual for Transmission Disassembly and Assembly procedures. If contamination is present, a full disassembly and cleaning will be required. Follow all the normal service procedures as indicated in the appropriate Workshop Manual.
I was afraid that it may be something like this, but wanted to verify. Thanks for your fast response and answer.