Dying Auxiliary Battery Causing Electrical Chaos in Silverado

I had a very similar issue with my 2015 Chevy Tahoe last year, and I have some experience working on electrical systems. The symptoms you're describing match almost exactly what I experienced, especially the weak starting and electrical gremlins. My auxiliary battery was failing, causing low voltage issues across multiple systems. The power management system was getting confused by the inconsistent power supply. The fix required: Full system diagnostic, Replacement of the auxiliary battery, Recalibration of the power management module, Testing all electrical subsystems Total repair cost was around 290 for parts and labor. The shop found the auxiliary battery was only holding about 40% charge capacity. Before suggesting specific fixes though, could you share: Any specific error codes you're getting? How old is your main battery? Are the issues more frequent when it's cold? Have you noticed any pattern to when the electrical problems occur? This info would help determine if you're dealing with the same battery malfunction I experienced or something else in the electrical system.

After checking the codes today at 21022 KM, turns out my auxiliary battery is indeed failing, causing major power management issues. The main battery's performance dropped significantly when tested, around 35% capacity. Previous maintenance records show no battery replacement since purchase. The low voltage warnings pop up mostly during morning starts, and the electrical glitches are getting more frequent. Got error code P0562 which points to system voltage problems. Battery malfunction seems to affect multiple systems now. Scheduled a battery replacement next week. Tech suggests replacing both main and auxiliary batteries as a set to avoid power distribution problems. Makes sense given the age and symptoms. Will update on the fix results. Thanks for sharing your repair experience, pretty much matches what I'm dealing with.

Yeah, I totally get what you're going through with those power management headaches. After replacing both batteries in my Tahoe like you're planning to do, it was like having a different car. Just make sure they sync the new auxiliary power system properly, that was key in my case. That P0562 code is definitely the smoking gun, saw the exact same one when my system voltage went wonky. The 35% capacity you mentioned is actually worse than what mine was showing (40%), so you're making the right call getting both batteries done together. Quick tip from my experience, after the battery replacement, keep an eye on the charging system for the first few days. My car needed a couple of drive cycles before the power management system fully adjusted to the new setup. Don't worry if you see occasional warning lights during this period, it's normal while the system recalibrates. One thing worth mentioning, have them check the alternator output while they're at it. When my car electronics were acting up, we found the alternator wasn't charging the auxiliary battery quite right, even though it tested okay on basic checks. A deeper diagnostic saved me from future car electronics issues. The morning start problems should clear up completely once you've got fresh batteries and everything's properly calibrated. My car starts like new now, even in cold weather.

Thanks for that detailed advice about the alternator check. Coming back with an update, had both batteries replaced yesterday at 21,089 KM. The voltage drop issues are completely gone and the car electronics are functioning normally again. The tech found minor corrosion on the auxiliary battery connections, which was contributing to the power management problems. They cleaned everything up during installation. The engine start is much stronger now, and all those unusual electrical glitches have disappeared. Interesting note about the system recalibration, saw a couple warning lights this morning but they cleared after a short drive, just like you mentioned. The power management system seems to be adjusting well to the new setup. Took your advice about the alternator check, output tested within spec, but they adjusted the charging parameters anyway as a preventive measure. Total repair came to 310 including the diagnostic work. Starting to realize how much those failing batteries were affecting everything. Definitely the right call replacing both batteries as a set. No more electrical gremlins so far.