Buick rainer code p0506

run fault codes
indicates an electronic problem with an overheating component
possible ECM ( check using a known good unit as a replacement), crank/ cam position sensor

Here is the fuse box diagrams for the 2 different engine options...and the 2 different box locations
Buick Rainer 2003 2006 fuse box diagram Auto Genius
HOWEVER ... I do not think there is an associated fuse for cruise control. That function is totally run from your on board computer (ECM). What can make the cruise not work is if any fault codes have occurred... Has your check engine light come on?
Some people with the same problem (that do not have an OBDll scanner to read or clear codes) disconnected their battery to reset the ECM. The cruise control then worked .... but if the root cause of the fault is not fixed ... then the same thing will likely happen again
Helpful?
Good luck with your troubleshooting

P0306 is a misfire on cylinder #6 P0174 is a lean code for bank 2 ,P0506
https://www.obd-codes.com/p0506

Check for codes first,Start car put in revers and turn off.Do this 3x.

PO 128 is a coolant temperature beyond threshold code. It means your thermostat is stuck and needs to be replaced.

did u have the computer cleared it will not clear its self u can go to most any auto parts they will clear for free

Take it to a qualified repair shop an have it diagnosed properly !

the most common solution to this code is replacing the thermostat. Very common i many GM vehicles.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

On this website you find fuse box diagram and description for Buick Rainer (2004)

http://www.carknowledge.info/buick-rainer-2003-2006-fuse-box-diagram

http://www.autozone.com/autozone/parts/Duralast-Idle-Air-Control-Valve/1999-Buick-Lesabre/_/N-jd47xZ9gsof?itemIdentifier=91113_0_0_Idle control system high(rpm).This is what it states for code P0507.Code P0506 is for low(rpm).Buicks have a history for sensors that go bad and hard to find which one without replacing some that are good.Here is a part to check out,Click on link to view.