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For several months now my 2015 Sierra Denali 2500 Duramax batteries go flat after 2-4 days sitting. I just installed two new GM Gold batteries. An obvious problem is that the backlighting on various interior controls, including: Red lighting around the headlight switch and drive mode selector; lighting for trailer brake controls; dimmer switch light; lighting for passenger and driver reading light switches, also rear seat reading light switches; and lastly, piano key (aux switches?) switch lighting. See the attached photo of the drive mode selector and trailer brake controls. Photo was taken after the truck hadn't been driven for 24 hours - red backlighting and white control illumination should NOT be on. But they and all the others are. What I've done: 1. Removed all the fuses from the driver side dash panel fuse block: lights stay on. 2. Disconnected the bulkhead connector from that fuse block: lights go OFF. BUT: after manually turning the headlights on - the backlights ALL go on again, then fade out slowly (like they are supposed to)when I turn off the headlights. 3. Disconnected all the wiring going to the K9 BCM controller (behind the OBD port). Lights stay on. 4. Put the truck in Transport Mode. Lights stay on. 5. Took the truck to a large nearby GMC dealer They charged me $228, replaced a fuse for the Trailer Brake Controller, and told me I needed two new batteries before they could go any further. (I bought two new batteries at a much lower cost and installed myself.) I am hesitant to return to that dealer... The truck has only 79,000 miles. Any suggestions?

Hello - I have a 2010 Suburban LT 4WD, and have narrowed down a parasitic draw to the BCM fuse on the inside fuse panel. If we don't drive the vehicle for 2+ days, I have to jump start it. Let me preface this with some facts. I've replaced the battery recently, and there is nothing plugged in to any of the accessory outlets. I have an aftermarket radio and DVD player, but they are wired correctly (DVD NOT wired to the dome light, radio uses a wiring harness adapter, so pretty certain that it is wired correctly). I've seen the TSBs about the 2007 models BCM, but this is for a 2010. Now back to the issue. At rest, after 10 minutes or so, the truck has about a 300ma draw (still relatively high - normal is somewhere around 50ma). Then, every 10 minutes or so, I get ~ 2A spike, then it drops back down to 300ma. The draw only drops when I pull the BCM fuse: down to ~ 50ma (normal). No other fuses (I tried all of them - under the hood and inside) have any effect on the draw. I've also heard some odd clicking coming from under the dash somewhere that seems to coincide with these spikes, not sure if that is related. Chevy dealer wants $300 to diagnose it, and (they say likely) $600 for a new BCM. They say flashing it wouldn't do anything. If it is definitely the BCM, I'd rather find one on ebay for much cheaper and (try to) have a shop reprogram it. Is that possible? Just wanted to reach out and see if anyone has any insight on what to try next?