After many PMs on fb, here is what i did for cruise control. You will need CAT ET to configure it correctly. Switches i used came out of a junk freightliner M2 truck and fit good in the square switch holes, but you need a on/off and a 3 position momentary switch. Also need 3 pins to plug in to the ecm connector, i used a old harness i had and unpinned 3 wires. On the ecm plug (truck side plug, rear most plug) pin 59- cruise on/off. Pin 44- resume, Pin 35- set, Both switches need to be ground switched. Not power. You need to configure the low speed cruise from 127mph to 15mph, in cat et, and maybe something else. Can also set rpms at idle to what ever you want using the switches, same as a semi truck.