Throttle Solenoid Positioner (TSP)

Fig. 29 Throttle solenoid positioner (TSP) w/dashpot:

WITH DASHPOT
The TSP with dashpot, Fig. 29, used on some vehicles, acts as a variable throttle stop by extending its plunger when the solenoid is activated and retracting the plunger when the solenoid is de-energized. When energized, the TSP holds the throttle at an idle position. When de-energized, the TSP functions as an anti-dieseling device by retracting its plunger and fully closing the throttle. A TSP may also be used to increase throttle opening when the A/C is in operation.
Two types of TSPs with dashpot are used: the adjustable plunger rod length type and the fixed plunger rod length type. The TSP with dashpot does not exert sufficient force to open the throttle, however, it will hold throttle open after it has been mechanically opened.

Fig. 30 Throttle solenoid positioner (TSP) w/vacuum operated throttle modulator (VOTM):

WITH VACUUM OPERATED THROTTLE MODULATOR (VOTM)
The solenoid portion of the TSP with VOTM, Fig. 30, used on some vehicles, may be used as an anti-dieseling TSP or an A/C TSP. The vacuum portion can be used for maintaining a cold idle RPM or as an A/C VOTM. The VOTM, operating the throttle through a connecting lever, may be activated by an electric vacuum solenoid or other vacuum control device.