Possible Causes

WARNING: This page is about a different car, the 2003 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

Possible causes are:

Cruise control switch malfunction
Connector or terminal malfunction
PCM malfunction
Short to GND circuit in Red/Blue wire between cruise control switch 8-pin harness connector terminal "B" and PCM 27-pin harness connector terminal "3P".
Short to power circuit in Red/Blue wire between cruise control switch 8-pin harness connector terminal "B" and PCM 27-pin harness connector terminal "3P".