Factory JBL system sound issue

I believe I have the non nav factory JBL system and a previous owner installed a cheap pioneer head unit with Nav/back up camera.

My issue is that it sounds like the speakers cut in and out to about half the volume (both driving and sitting still), the subwoofer doesn’t seem to be working, and the door speakers have no treble, just bass. The quality sounds good when it’s working correctly which is about 20% of the time...

Could this be a factory amp issue, HU, bad speakers, or bad connections? Anyway to test speakers with ohm meter?

From my research I’ve found that the head unit powers the dash speakers and amp powers the doors. Is this correct even on JBL system?

Just need some guidance please.

 

*** I have a 2012 with factory JBL premium. I have the factory head unit and factory amp still connected. If it is anything like mine you should have 12 speakers in the truck 3 3.5 in front dash, 2 6x9 mid subs and 2 tweeters in front doors, and 2 6.5 and 2more tweeters in back doors, and 1 8in sub behind backseat on driverside. The front 6x9s are mid subs. The do not produce any highs. The back doors are wired together and are not crossed over. The head unit does power the dash and amp does all the rest. Check wire connections is where I would start. Maybe have something shorting out that would be caused by bumps and turning sharply. Check to see if the head unit has a DPS setting. That raises and lowers volume based on speed and cabin noise. It maybe set too sensitive. I have found that just replacing the speakers made a huge improvment in the sound quality in the vehichle. And sound deadning the doors helps keep the sounds from outside on the outside.

 

Thanks! I wasn’t aware of the front speakers being mid subs but that makes sense. I did check the dash speakers and I think all 3 are 3.5”.
I’m gonna tear into it all on Tuesday and check the connections behind the head unit and check the amp also. I would like to eventually replace all the speakers too.
I have a 4 channel amp sitting in my basement that I’d like to wire to the speakers as well when I get them but I’ll need to refer to a diagram for help.

 

Check out *********.com. They sell new systems that are plug and play designed specifically for Toyota’s. Even if you don’t decide to upgrade to their system, they have diagrams and YouTube videos with how Toyota wires the system. Check them out!

 

Middle dash speaker 3.5 fits well, sides will need smaller speakers or dash trimmed.

 

When you replace dash speakers , check the mounting depth or the outside 3.5 will sit on the vent tubes and they will not set flush for mounting. If you have to trim (which I end up doing) a Dremmal makes it easier. Much luck to ya.

 

Thanks! A lot of new info I wasn’t aware of.