Mazda Trucks 1987-1993 Repair Guide

Vacuum Controlled Systems


See Figures 1, 2 and 3

The vacuum controlled cruise control system consists of the following components:

Control switches
Servo or vacuum actuator (throttle actuator)
Speed sensor
Stoplamp/brake switch
Actuator cable
Cruise control unit
Clutch switch (manual transmissions)
Vacuum dump valve (Navajo)
Amplifier assembly (Navajo)
Transmission range switch (Pickup and MPV)

The throttle actuator is mounted in the engine compartment and is connected to the throttle linkage with an actuator cable. The speed control amplifier regulates the throttle actuator to keep the requested speed. When the brake pedal is depressed, an electrical signal from the stoplamp switch returns the system to stand-by mode. The vacuum dump valve also mechanically releases the vacuum in the throttle actuator, thus releasing the throttle independently of the amplifier control. This feature is used as a safety backup.

Click image to see an enlarged view

Fig. Fig. 1: Cruise control system components-Pickup

Click image to see an enlarged view

Fig. Fig. 2: Cruise control system components-Navajo

Click image to see an enlarged view

Fig. Fig. 3: The cruise control actuator unit is mounted on top of the right side strut tower in the engine compartment of the MPV