Weird voltage drop when coming to a stop

I’ve been having a weird/ random voltage drop over the last couple of months, sometimes when coming to a complete stop my voltmeter will drop down to 12-12.5. I can hear the fan motor bog down as well. I can also replicate by pressing down hard on brakes while sitting still in the driveway. Am i being paranoid or is the electronic brake controller acting up or is this normal operation.

Thanks in advance

 

Check / clean / tighten your battery terminals

Load test your battery , (parts places will do it for free.)

 

Got any electrical mods? Lights, winch, etc?

 

Might be a battery issue. But not bad enough to completely fail on you

 

I just cleaned the terminals and I’ll get the battery tested next week. I should mention the battery was replaced ~9 months ago with an autozone AGM battery.

Just a few electrical mods. Nothing recent though...

 

Not sure why my post is not showing up. Your problem is the AGM battery. Guys on here have to modify our system to 14.5 volts to properly charge an AGM battery

 

I should’ve mentioned in the original post. I am OvTuned and I’ve adjusted the alternator output. The voltage drop is also happening on the factory tune.

 

Sounds to me that the most likely candidate is a bad ground or wiring issue. Have you done a visual check on your brake lights to ensure that they're operating correctly? Check all light brake light sockets to ensure they're clean and free of crud, and all brake/rear-light related grounds, as well as the brake light switch. Do you have anything connected to the 7 pin trailer harness?

 

Nope nothing is connected to the 7 pin. Brake lights are also working properly. Grounds are also tight/ clean.

 

Perform a voltage drop test on the battery and ground cables. Some times the cables look fine but has corrosion eating up the wiring inside. Since it looks like you’re an audio guy do the big 3 upgrade and see if that helps.

 

When ya press on the brakes HARD, it'll tell the booster to do its job. Maybe ya got some wires compromised going to it with that added aftermarket power distribution.

 

I installed an agm battery and a volt meter with only three accessories and I’ve noticed when driving, it reads around 13.8 and sometimes when I come to a stop, it drops to 13.2 but everything seems fine.

 

That's a good sign, but not definitive; check your grounds using an incandescent test light, and definitely re-check everything in your added power distribution install, starting with the voltage drop test mentioned above.

 

I can replicate the voltage drop while sitting still in the driveway but when it drops when coming to a stop I’m not pressing abnormally hard on the brakes. I disconnected my power distribution and I’m still having the voltage drop. I’m planning on going to autozone this week and having them test the battery.

 

For the system to work you just need to press the brake. Pressing fast/hard makes it actuated faster among other inputs it receives (vehicle speed, steering angle, etc)
You can change your brake fluid without an additional pump by loosening the furthermost brake line and pressing the brake while keeping in sight the level of the fluid as it drains and you add new fluid.
The setup in your version Tacoma is not vacuumed controlled/actuated.
May be too much info...