Forester (2006) Head unit / entire car randomly loses power for a half second.

[CoolCat]

Hey all - So this is a weird one. Just the past year I've had this issue where every few minutes my head unit reboots, my sub makes a loud noise, and I think some lights on the dash flash as well. I had a friend install an aftermarket head unit, speakers, and sub 4 years ago in my car. He did a very legit job, inline fuses and everything. Not sure if this is related.

It feels like a temporary short or blown fuse or something? But it only lasts a half second then everything boots back up including my CarPlay unit.

Some weeks it doesn't happen at all. Some weeks it happens ALL the time. It might be a placebo effect, but it might be connected to how much electric I'm using (heated seats, blowing heat, speakers loud, windows, pressing brakes)...

Where do I even start diagnosing this? I'm not very electrical inclined. Any ideas?

 

[Kevin]

The speakers are probably so loud they are causing vibration and making circuits disconnect; and maybe don't use heated seats or brakes

I start by carefully inspecting the relative fuses especially if they are of the wire type as there may be a break that only disconnects when hot or caused by vibration. Of course it's very difficult to diagnose electrical problems unless you have a multimeter - and know how to use it.

 

[Jwind0805]

Hey man. This happens to me every once and awhile. Not the entire system, but similar sound misfunctionals. Lights would dim sometimes. A yellow top optima and a capacitor cured it.
Go with what Kevin said first. Then check all your battery wiring and grounds, plus how old the battery is.
If it's still happening a capacitor for the sub might be best.