On some vehicles, engine vacuum is used to operate the cruise control and heater/AC mode and temperature function. If vacuum is lost these systems will not function correctly. The check valve will is a one way valve that allows vacuum to be supplied and also traps vacuum for the accessory system during times of low engine vacuum - under heavy engine load, when the throttle is open.
The federal government work with the auto manufactures to decide which vehicles should be recalled and for what. Please see the following RepairPal article for more information - http://repairpal.com/recalls-what-they-mean-what-to-do
The hazard switch is part of the turn signal switch on your 1999 Cadillac DeVille. The red button is held on by a small screw. I don't think you can purchase the button, spring, and screw separately from the turn signal switch. The airbag, steering wheel, and lock plate must be removed to replace the turn signal switch, special tools are required.
A plugged catalytic convertor will not make the cooling fans stop working.
Many brake estimates are included in the RepairPal estimator. Please visit the following link - https://repairpal.com/estimator?car_type_id=3928
Unbolting the brake calipers totally would cause them turn with the rotors when the brakes are applied, resulting in damage to the braking system! Unwanted ABS activation is commonly caused by a faulty wheel speed sensor.
Many states now REQUIRE replacement catalytic converters to be smog certified. Some universal (and bolt on) converters do not meet the certification standards. You must make sure whatever type of converter is installed, it meets the latest smog standards. The convertor manufacture should be able to provide certification information.
It could be a faulty low oil level switch.
Does your Malibu start and die or does the engine cranks over and not start at all?
Check the ILLUM fuse #14 in the instrument panel fuse box of your 1999 Cadillac Escalade