The following article is about cruise control system of the 1988 Jeep Cherokee. Cherokee uses an electro-mechanical servo system. The system consists of a control module, speed sensor, servo, control switch assembly, vacuum storage canister, check valve and release system. Release system consists of a mechanical vacuum vent valve and brake and clutch (M/T) release switches.
Cruise control switch is an integral part of turn signal switch lever and consists of 2 separate switches. First is an “ON-OFF” and “RESUME” slide switch located on flat of directional switch lever. System will automatically disengage when brake or clutch pedal is depressed. It can be re-engaged to previously selected speed by accelerating to 30 MPH and moving slide switch to “RESUME” position, then releasing switch.
Release system deactivates cruise control system when brake or clutch pedal is depressed. Either servo vent valve or mechanical vacuum vent switch admits atmospheric pressure into servo when brake pedal is depressed.
Find more information about Jeep Cherokee Cruise Control System 1988 here. (source: jeepgarage.free.fr)