I was told the alarm was the cause of speakers not paying loud, is this true or does anyone know?

why guess and at the same time pick the most expensive cure
if EFI fails, (electronics) gee 10 new engine will not cure it. (this EFI ) there are many tests to do , to learn TRUE CAUSE/
we can't do the tests for you but sure can name 20.
using tools, you do not have
why not pay shop to do only diagnosis.
not told you what heating problems means/
engine runs a 150f and thermostat is bad?
or that the cars cab heater is dead?
or engine overheats?
we can not guess evidence, here./
check fuses yet
scan the PCM
no year car told but is it 2023 minus 7 ?
no engine told, no VIN told
as you can see we are blind here.
why not start a post that shows all what heating ,means
elaborate all that and get good answers, not guessing , tests.
we do tests,that is how this works.Just like your Doctor does.
scan the PCM and see your errors. is a great start
do Diagnosis DIY or pay the shop.

You have a radio problem not a wiring problem.

I don't know who told you that , a semi- clogged catalytic will cause a low power issue an maybe a couple of DTC'S diagnostic trouble codes P0420 - P0430 ,Has nothing to do with the alarm system ! Do you mean Service vehicle soon or SERVICE ENGINE SOON ?
SERVICE VEHICLE SOON
The IPC illuminates the SERVICE VEHICLE SOON indicator in the message center when the PCM or the BCM detects certain non-emissions related malfunctions. The IPC receives a class 2 message from the PCM or from the BCM requesting illumination. What problem are you having with alarm system ? If you have a starting issue it's the Anti-Theft system not alarm system . The alarm would go off if you vehicle was broke into . I don't know what shop you took it to but did you try a dealer ?

How to Diagnose Codes P0420 P0430

IT is possible that the battery removal will affect the CPU program which controls the immobiliser as some times the power surge on reconnection causes this. Useing a scanner to reset the CPU program should fix the problems

General advice:Commun alarm loud speakers don't have a volume control as it is meant to be loud (db by low think about 110,may be wrong...).Good practice:track the speaker,reorientation may help lower the noise,if not try to put a mask on it (textil...)Cheers.If u find out a volume adjust form (knob,pin)let the people know.Note:good electronist hobby may install adjust on wires if speaker aloud it.

the alarm system was most likely not installed correctly, when you install an alarm system you need to know what you are doing or you can cause countless problems in wiring, as for the gauges i would suggest checking all wiring behind the cluster (gauge panel) look for wires that have been cut and if you can not find anything i strongly suggest taking it to a mechanic for trouble shooting.

Wheel bearings are sealed on this particular GM vehicle. First thing to try is to place the front tires on the back of the vehicle and see if the sound changes. If the sound still comes from the front, have the wheel bearing checked at your local service center. Expect to pay between $200-250 to replace. If you decide to do it yourself, you can find the part for $60 at places like RockAuto.com.

Wheel bearings will generally last around 200K miles before they begin to show signs of failure. If you hit a curb on that side recently, that could cause a premature failure.

check the ground wires for the radio make sure that they are clean and tight

You can find out prices at autozone online. If you give me the engine size and what your problem is in detail I will try to he;p you for free.

http://www.themotorbookstore.com/carmanuals.html
This is a link to get the cars book, they will mail it to You, other wise the dealer, but at a higher cost