RAM 1500 Van V6-3.9L VIN X (1997)
Cruise Control Vacuum Reservoir: Description and Operation
SYSTEM OPERATION
The vacuum reservoir is mounted near the speed control servo on the right cowl side panel in the engine compartment. The reservoir contains a
one-way check valve to trap engine vacuum in the reservoir. When engine vacuum drops, as in climbing a grade while driving, the reservoir
supplies the vacuum needed to maintain proper speed control operation. The vacuum reservoir cannot be repaired and must be replaced if faulty.