2015 Silverado 2500 battery/trailer brake issue

[deerefan]

In a previous post, we posted we bought a 2015 Silverado with 43k miles. Just went on a 600 mile trip pulling about 7k lbs. The drive there went fine. We hooked up to the trailer Saturday evening to leave early Sunday morning. I disconnected the trailer whip from the truck plug. Sunday morning, the battery was dead. Jumped it off, now getting a service trailer brake notification on my dash. We drove it home, not sure trailer brakes were working (did not show gain on dash meter when brakes were pressed but could adjust gain at controller). Once home, I shut the truck off, disconnected from the trailer and went in. Came back an hour later and metered battery-showing 11v. Truck won’t start. I am trying to figure out if there is a draw or issue with brake controller or if the battery just went bad. Not sure if battery age, it is a duralast, not the original battery.

 

[George2615]

I have a 2016 2500HD and had the same service trailer brake message. Mine happened at only 20K miles. I found on the web it is caused either by the trailer brake controller located in the rear (usually mounted above the spare tire) or a bad ground. Mine was a bad ground wire to the frame. I removed the wire and wire brushed the frame and terminal and reconnected. I did buy a replacement controller but haven't had to install yet. There are videos on the web about servicing the brake controller.

As far as the battery draw, you will have to check to see what is drawing voltage/current. It could be the battery but usually is due to some accessory left plugged in. I left a GPS plugged in and after 4 days it drew my battery down enough to not let it start. I don't use my truck much anymore. It's now 6 1/2 yrs old and only 25K miles.

 

[LD1]

Unlikely an issue with brake controller. Probably just a battery, especially if original 2015 battery....its due.

The "check trailer" or "trailer disconnected" or whatever warning on the dash always pops up if the trailer is hooked up and you disconnect it when the truck is running (or at least the key is on). Cause it senses that there WAS a trailer hooked up and now it isnt. Shutting off and restarting should make that warning go away.

But if your batter is dying off with trailer UNHOOKED, the trailer aint the problem.

You need to check the batteries parasitic loss. less than 50mA is usually the target.

If you have a DVOM, put it on mA setting. For this you have to unhook a battery cable and test in series. BUT, on these new computer controlled vehicles they take several minutes to power down computers and such, and for the first few minutes after reconnecting the power (with the meter inline), it will draw MORE current than the MA setting on the meter can handle and you will blow a fuse inside your meter.

So the work around is to unhook the battery cable and reconnect with with a little alligator clip wire. Wait 5 min. Then put the meter between the battery cable and post.....now current has two paths (through the meter AND the alligator wire). So now that the computers have shut down, remove the alligator clip and observe the current draw on the battery.

Make sure doors are closed, ignition is off, and unhook the underhood light if it has a working one.

Less than 50ma. If you have significantly more than that, start pulling fuses one at a time until you find what is continuing to draw current.

 

[deerefan]

Unlikely an issue with brake controller. Probably just a battery, especially if original 2015 battery....its due.

The "check trailer" or "trailer disconnected" or whatever warning on the dash always pops up if the trailer is hooked up and you disconnect it when the truck is running (or at least the key is on). Cause it senses that there WAS a trailer hooked up and now it isnt. Shutting off and restarting should make that warning go away.

But if your batter is dying off with trailer UNHOOKED, the trailer aint the problem.

You need to check the batteries parasitic loss. less than 50mA is usually the target.

If you have a DVOM, put it on mA setting. For this you have to unhook a battery cable and test in series. BUT, on these new computer controlled vehicles they take several minutes to power down computers and such, and for the first few minutes after reconnecting the power (with the meter inline), it will draw MORE current than the MA setting on the meter can handle and you will blow a fuse inside your meter.

So the work around is to unhook the battery cable and reconnect with with a little alligator clip wire. Wait 5 min. Then put the meter between the battery cable and post.....now current has two paths (through the meter AND the alligator wire). So now that the computers have shut down, remove the alligator clip and observe the current draw on the battery.

Make sure doors are closed, ignition is off, and unhook the underhood light if it has a working one.

Less than 50ma. If you have significantly more than that, start pulling fuses one at a time until you find what is continuing to draw current.

Seems you nailed it. Put new battery in and everything working as it should.

 

[LD1]

Seems you nailed it. Put new battery in and everything working as it should.

Still be a good idea to check the parasitic loss on the battery...

But if it was the original....you probably all good and it was just time. Actually made it longer than the two 2015 trucks I service for my buddies mowing business. And every since the new body style on 07 or so....they took a step backwards on battery location and ease of changing....let alone every try and get a good bite with jumper cables...

 

[workinonit]

Unlikely an issue with brake controller. Probably just a battery, especially if original 2015 battery....its due.

The "check trailer" or "trailer disconnected" or whatever warning on the dash always pops up if the trailer is hooked up and you disconnect it when the truck is running (or at least the key is on). Cause it senses that there WAS a trailer hooked up and now it isnt. Shutting off and restarting should make that warning go away.

But if your batter is dying off with trailer UNHOOKED, the trailer aint the problem.

You need to check the batteries parasitic loss. less than 50mA is usually the target.

If you have a DVOM, put it on mA setting. For this you have to unhook a battery cable and test in series. BUT, on these new computer controlled vehicles they take several minutes to power down computers and such, and for the first few minutes after reconnecting the power (with the meter inline), it will draw MORE current than the MA setting on the meter can handle and you will blow a fuse inside your meter.

So the work around is to unhook the battery cable and reconnect with with a little alligator clip wire. Wait 5 min. Then put the meter between the battery cable and post.....now current has two paths (through the meter AND the alligator wire). So now that the computers have shut down, remove the alligator clip and observe the current draw on the battery.

Make sure doors are closed, ignition is off, and unhook the underhood light if it has a working one.

Less than 50ma. If you have significantly more than that, start pulling fuses one at a time until you find what is continuing to draw current.

Or get a clamp on current meter. That's what I use.

 

[alexpops]

Had the same thing happen with my 2011 silverado 2500 hd. It was the abs controller, which in my case took over a year to source. Parasitic draw, check trailer brake, stability control, loss of cruise control, etc. Whole bunch of bcm and abs codes. Once i got and replaced the ebcm, problems went away. Internals were shorted and full of crud. Relatively easy fix, and you should have an easier time sourcing the ebcm. Mine was a one year only, with the part changed in 2012.

 

[deerefan]

Had the same thing happen with my 2011 silverado 2500 hd. It was the abs controller, which in my case took over a year to source. Parasitic draw, check trailer brake, stability control, loss of cruise control, etc. Whole bunch of bcm and abs codes. Once i got and replaced the ebcm, problems went away. Internals were shorted and full of crud. Relatively easy fix, and you should have an easier time sourcing the ebcm. Mine was a one year only, with the part changed in 2012.

Thankfully no codes were ever thrown. The battery change got the “service trailer brakes” issue resolve. They are working now. The only thing weird is the infotainment system is still “glitchy” from time to time, but I have read this is a somewhat common issue with the software.

 

[deerefan]

Still be a good idea to check the parasitic loss on the battery...

But if it was the original....you probably all good and it was just time. Actually made it longer than the two 2015 trucks I service for my buddies mowing business. And every since the new body style on 07 or so....they took a step backwards on battery location and ease of changing....let alone every try and get a good bite with jumper cables...

Can’t agree more. Was real fun replacing the battery . The battery I pulled out was from the beginning of 2018.

 

[alexpops]

Hopefully your new battery takes care of the issues. I replaced my batteries (duramax), & it was fine for a day, then both batteries dead again next morning. 60 amp ABS fuse was blown, so I figured no power, can't be the EBCM causing this. All kinds of weird unrelated things ... erratic dash ... 90mph on speedo/then 0, then 40, then normal. Tranny shifts were out of sync, cruise control wouldn't work, fog lamp switch was heating up, radio (tied to speedo for volume/noise control) all over the place on volume, door locks erratic, and comm systems shut down so ECM wasn't getting info from the other modules. BCM, instrument cluster and Trailer Brake module are all fed through the EBCM (at least partially), AND the instrument cluster shares the ground under the driver side door. All those modules need good voltage or they act up. If you have a parasitic draw that reduces the battery voltage to less than an 80 or 90% charge, you may still start, but you won't run right & it'll be hard to narrow down the problem, since EVERY system is acting up. Mine was drawing 5 amps with both ABS fuses out, so there was some backfeeding going on in there between modules. Started acting up near Dallas, & by Bakersfield, I was afraid to shut her off for fear of not restarting. Got to SF Bay area/shut down in driveway, & took me a year to move her again due to national back order on part. Lucky I had another car to get me back across county. Fun times. Between that, erratic injector codes, CP4 worries, and a 2K estimate to pull the dash to replace a leaking AC evaporator made me not regret trading her in after fixing the ABS issue.