1988 - 1991 6.2's with the 700R4/4L60 did have a Throttle Position Sensor, not a Switch. The TCC lock on these truck is controlled by the PCM.
Adjustment is critical, ensure you adjust the sensor and roll the throttle through full throttle and observe voltage. You should see a smooth increase in voltage.
If not smooth, the sensor is bad, I have seen many of them defective and would cause the PCM to disable lockup.
Search the forum for adjusting the TPS on a 6.5 MFI truck (92-93) to get the procedure. Requires a digital volt meter.
The TPS from the 92-93 6.5 is the same, just has a different connector on the end of the sensor. I've swapped these in a pinch.
1982 C10 SCSWB 6.5TD, mods too extensive to list. (13.69 1/4 mile @94.6 MPH) RACE TRUCK
1982 C10 SCSWB 6.2NA, 2.73 700
1986 C10 SCLWB 6.2TD 3.73 700
1989 V20 SUB 6.2NA, 3.73 400
1994 G20 VAN 6.5NA, 3.42 60E
1994 K20LD ECSWB 6.5TD, 3.42 80E
1995 K20 SUB 6.5TD, Wrecked, ran into by stupid teen.
1995 C3500HD DRW 6.5TD, 12' Flatbed 5.13 80E
1995 C3500HD DRW 6.5TD, 18' Rollback Wrecker 4.63 80E
1994 C20HD ECLWB 6.5TD 3.73 80E Wifes Truck.
1995 C20LD ECSWB 6.5TD 3.73 80E
1995 K20LD SCLWB 6.5TD 3.73 80E
1996 K30 DRW 6.5TD 4.10 80E
1997 C10 Tahoe 2Door 2WD 5.7L to 6.5 Conversion Underway