So, I have a 2015 2500. It started happening about a year ago. Once every 3 months or so, after being parked at work for 6-8 hours, the batteries would be dead. Would get a jump and drive home. Now it happens way more frequently and I'm getting an "action needed" screen on the dash saying to roll the driver window down and back up again. Was told something about an occupancy sensor? Any ideas on what this could be?
random discharge of batteries
- Thread starter 1morebeer
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The batteries went down far enough that you lost the driver or fob memory positions. That procedure is to reset zero on a bunch of things.
You either have a module not going to sleep or one or both batteries are on the way out. Always replace them in pairs.
You either have a module not going to sleep or one or both batteries are on the way out. Always replace them in pairs.
A quick check of the batteries is after driving the truck go in and disconnect both batteries. Let them stabilize for about 10 minutes and write down the voltage on both. Let them sit for a day and go back and check voltages again. If you got a battery dropping voltage on you then you know you got a bad cell and like @Mikey52 said, always replace batteries in pairs. I did this same check on my LMM and the one battery was strong and the other dropped 1.5 volts overnight. Replaced both and been running strong. Good luck, Dean
Or stop in a Walmart and ask them to test the batteries. Make sure they disconnect one while testing the other, sometimes they 'forget' to do this. A shorted cell will present problems like this. The Dean E test does the same thing.
I had this problem with my 2015. After replacing the batteries so I knew I had good ones I put new groundwires in. Never had an issue again in the last year that I owned it before I sold it. GM has a lot of issues with bad groundwires. And I didn't go back with factory I made them myself. If you don't know how to do that most semi repaire/parts shops will make them for you.
I'm with ya. Grounds are a problem for GM. Kinda slapped together and little of any protection from the elements. My dad was an electrician so I got the heavy gage crimps in my shop. One ground I think is a must is between the engine block and the engine firewall. There is a ground there but not easy to reach and the ground points are less than ideal. Ran a separate #4 ground from the engine to the firewall as one of the first things to check when I was looking at electrical gremlins dealing with some of my modules on the low speed buss. Dean
I believe my 15.5 also has a ground issue. Batteries go down over night only when negatives are connected. Long story shortened my truck just quit one day while driving down freeway. No smoke, no stall, just lost power and knocked a bit before coming to a stop. Found positive burned likely touched firewall. Only gauge I remember odd before coming to a stop was voltage maxed out. Replaced everything I found and still looses voltage and will not start. 5 injectors shut down. Desired rp but no actual. Have already purchased another set of batteries as the new ones I replaced kept draining to 4 volts and wont charge to 100 percent, so I have new ones in. Also had a ticking buzzing relay which also appeared to make the injection pump buzz. Replaced two relays drivers side fuse box. No buzzing from what I can tell now. Checked both regulators no debris found. Note.....the night before this happened I raced 3 sportbikes and was neck and neck with 1st one when I let off at 130.....ran fine rest of night and next morning. That afternoon is when it just quit.
Can someone chime in and tell me where all grounds are.....I am aware of frame under driver, one on drivers firewall and others on block I have cleaned those but they are original. Trailer brake fuse is pulled and onstar fuse. Still drops but only when negatives are connected.
I have tried contacting my tuner for help but no replies. I apologize if posting in wrong location moderator welcome to move my questions if needed.
all help appreciated i believe i have more than this electrical issue though.......will need help and likely walk through with someone willing to help over the phone.......thanks
Can someone chime in and tell me where all grounds are.....I am aware of frame under driver, one on drivers firewall and others on block I have cleaned those but they are original. Trailer brake fuse is pulled and onstar fuse. Still drops but only when negatives are connected.
I have tried contacting my tuner for help but no replies. I apologize if posting in wrong location moderator welcome to move my questions if needed.
all help appreciated i believe i have more than this electrical issue though.......will need help and likely walk through with someone willing to help over the phone.......thanks
See attachment. Disconnect one battery cable (either neg or positive one battery only) and leave the other connected, then work on your battery problem. If no problems with just one battery, then disconnect the good battery and connect the bad battery and see if you can locate the problem. A dual battery setup can be difficult to troubleshoot. True, it shouldn't make a difference, but sometimes it does.
Getting your truck to start is another problem that will likely be easier to solve with a good consistent electrical supply than without.
You may be able to find an electrical manual on the gmupfitter website. https://www.gmupfitter.com
Getting your truck to start is another problem that will likely be easier to solve with a good consistent electrical supply than without.
You may be able to find an electrical manual on the gmupfitter website. https://www.gmupfitter.com
Thanks for replying. I am positive both batteries are good. They hold charge disconnected and with both positives connected in truck. I suspect a ground issue or module. My turbo burned through the cable running above on the firewall. I have replaced it and have it wrapped in a sleeve to protect it from the heat. Thanks for the link. The truck has literally sat in my warehouse since March 2021 I have not had much time to work on it. I am just now getting around to it.
I may have a bad cp4 also although no debris is evident. I have not done a fuel return test and have not pulled injectors or glow plugs but plan too. I was hoping it was only the cables but I do believe I have more issues.......oddly about a year before this happened the auto start on fob would just click sometimes instead of starting. Not all the time but seemed more often as time passed. Then trailer brake message appeared, then radio quit, then came back.....definately electrical. I recall going over all wiring underneath especially under the bed. I wrapped some several years ago to help protect the long runs as my truck saw alot of highway miles plus off road alot for business.
I am fairly competent with the truck Ive had 4 dmaxes since the LB7, all have been semi-built.....just never blew one up so never needed engine rebuild......this may be my first.......thanks again.
Is there a way to test the cp4 other than pressures? Or do I need to pull it and visually inspect?
I may have a bad cp4 also although no debris is evident. I have not done a fuel return test and have not pulled injectors or glow plugs but plan too. I was hoping it was only the cables but I do believe I have more issues.......oddly about a year before this happened the auto start on fob would just click sometimes instead of starting. Not all the time but seemed more often as time passed. Then trailer brake message appeared, then radio quit, then came back.....definately electrical. I recall going over all wiring underneath especially under the bed. I wrapped some several years ago to help protect the long runs as my truck saw alot of highway miles plus off road alot for business.
I am fairly competent with the truck Ive had 4 dmaxes since the LB7, all have been semi-built.....just never blew one up so never needed engine rebuild......this may be my first.......thanks again.
Is there a way to test the cp4 other than pressures? Or do I need to pull it and visually inspect?
Any corrosion on the battery terminals at all? We chased an issue on a 6.0L gasser 2012 and that's all it turned out to be was a corroded negative terminal. Couldn't tell on the outside the battery cable but underneath the the cable between it and the post it was caked.