I suspect BCM... thoughts?

[TrybalRage]

Well, unfortunately it left me sit again today. Same behavior. No gear indicator when key on, no crank.

Ugh.

Battery is back down to 12.25 volts as well. So either this thing isn't holding a charge, or something's still drawing it down. It's still under warranty so I'm going to replace it either way.

 

[TrybalRage]

Well my current draw (if I did it right) is right around 13mA. Alternator is putting out 14.8V. Took the battery to Autozone and they told me it tested fine, but when I take it home and put it on the charger it's only showing half full.

 

[Geotrash]

Is it an AGM battery? I’ve had the same thing happen with an AGM battery and thought I had a parasitic drain. New conventional battery solved the problem for good.

 

[TrybalRage]

Is it an AGM battery? I’ve had the same thing happen with an AGM battery and thought I had a parasitic drain. New conventional battery solved the problem for good.

Nope, conventional Duralast Gold from autozone. Of course if their little tester doesn't show an issue, they won't replace it under warranty.

 

[sunureu13]

That sucks Have you tried checking grounding through all the pins for the BCM connectors?
BCM was my issue but now I'm having trouble programming my BCM. That's an issue for another thread though.

 

[TrybalRage]

That sucks Have you tried checking grounding through all the pins for the BCM connectors?
BCM was my issue but now I'm having trouble programming my BCM. That's an issue for another thread though.

No, I have not. I've been focusing on why this damn battery keeps losing charge. Parasitic draw is around 14mA, which supposedly is acceptable. Alternator putting out over 14V. But when I drive it and then check it a little while later, voltage is down.

Seems like when I get a no-start/no-response condition, the voltage is around 12.25 every time. When I put the battery on a charger and get it to a full state, it seems like I don't have the problem for a little while. So I don't know if when the voltage drops <12.3 it's making the computer(s) freak out?

Maybe I'm chasing the wrong thing. But the parts store tells me the battery is fine. However when I put my charger on it, it takes forever to get fully charged. Is a "slow charging" battery a thing? Like the car is drawing down more than the battery will accept in return from the alternator?

 

[Fless]

No, I have not. I've been focusing on why this damn battery keeps losing charge. Parasitic draw is around 14mA, which supposedly is acceptable. Alternator putting out over 14V. But when I drive it and then check it a little while later, voltage is down.

Seems like when I get a no-start/no-response condition, the voltage is around 12.25 every time. When I put the battery on a charger and get it to a full state, it seems like I don't have the problem for a little while. So I don't know if when the voltage drops <12.3 it's making the computer(s) freak out?

Maybe I'm chasing the wrong thing. But the parts store tells me the battery is fine. However when I put my charger on it, it takes forever to get fully charged. Is a "slow charging" battery a thing? Like the car is drawing down more than the battery will accept in return from the alternator?

Pretty much any draw under 50mv at full sleep is acceptable, although usually it's a bit less, around 30 or 40, so that seems to be okay. How are you measuring that, with an inline ammeter or an inductive clamp?

Battery charging rate is dependent on your charger's settings; does it indicate what the amp rate is when it takes forever to charge the battery?

 

[Joseph Garcia]

When you say that the auto parts store tested your battery, did they take it out of the truck and put it on a bench tester? IMO, that it the only real way to fully test a battery.

 

[TrybalRage]

Pretty much any draw under 50mv at full sleep is acceptable, although usually it's a bit less, around 30 or 40, so that seems to be okay. How are you measuring that, with an inline ammeter or an inductive clamp?

Battery charging rate is dependent on your charger's settings; does it indicate what the amp rate is when it takes forever to charge the battery?

It's not that fancy of a charger, it has 2-4-6 Amp options. This was on the 6A setting, from 12.25 to full takes like 12 hours or more. On other batteries I've used it on I can top them off in 2-4 hours.

Edit: I'm measuring by using a multimeter from the negative battery post to the cable when it's disconnected.

 

[TrybalRage]

When you say that the auto parts store tested your battery, did they take it out of the truck and put it on a bench tester? IMO, that it the only real way to fully test a battery.

I took it out of the truck and brought it in. They had a little box with what looked like jumper cable clamps on it. Of course I had recently topped it off when I took it in so the voltage was fine, but I thought it would be able to test for other stuff (amps, etc). Maybe not. I'm gonna let it draw down again (it's at 12.3V again right now) and take it in again.

 

[Doubeleive]

I took it out of the truck and brought it in. They had a little box with what looked like jumper cable clamps on it. Of course I had recently topped it off when I took it in so the voltage was fine, but I thought it would be able to test for other stuff (amps, etc). Maybe not. I'm gonna let it draw down again (it's at 12.3V again right now) and take it in again.

next time it won't start pop the hood and put your meter on it, then have a helper turn the key to start while you watch the voltage, the voltage should be 10.5v or more while the key is in the start position

 

[donjetman]

12.3 v is at 60% state of charge. That battery is junk. Its self discharging.

 

[TrybalRage]

12.3 v is at 60% state of charge. That battery is junk. Its self discharging.

I agree. It was bought new in November 2021 so I'd like to get it replaced under warranty. Just need Autozone to agree as well.

 

[Fless]

I took it out of the truck and brought it in. They had a little box with what looked like jumper cable clamps on it. Of course I had recently topped it off when I took it in so the voltage was fine, but I thought it would be able to test for other stuff (amps, etc). Maybe not. I'm gonna let it draw down again (it's at 12.3V again right now) and take it in again.

Anytime they test it they should give you a printout of the results. Should tell how many amps it can deliver.

 

[petethepug]

The slow charge is the best way to charge a standard lead acid battery. Step 2 is taking to a shop / store that can immediately preform a load test. If the battery fails that test you’ve got a bad cell. This means you can charge the battery to 12V + but you don’t have the cold crank amps to start the truck.

 

[Geotrash]

I had a bad battery in our Infiniti that was 9 months old. I swore I had a parasitic drain but like you it always tested low draw when I’d check. Every 4-5 days of sitting it would need a jump until it got to where it wouldn’t start after sitting overnight. Took the battery back to advanced auto where I bought it and they took it out and tested it in the store. Couldn’t find anything wrong so they wouldn’t warranty it. Told me I had a problem with the car’s charging system. So I went to Autozone and bought the cheapest conventional battery they had that fit properly, for $99 on sale. No more problems even after sitting for a couple of weeks.

My money is on the battery too.

Also, I will now only buy the cheapest conventional battery I can find.

 

[TrybalRage]

Well, ladies and gents, the saga continues.

I've been driving the suburban every day, so the battery should be maintaining a state of charge. But it seems low again, and I went to start it this afternoon and got all the same symptoms.

No gear position
No fuel gauge
Service 4wd
Service ABS

And so on.

I tried to plug in the Tech2, but it would just show 'no communication' for all modules until I disconnected/reconnected the battery.

Afterwards, I was able to do a scan and pulled 23 (!) codes. I took snapshots of them all at this imgur link:

https://imgur.com/a/orMsOgj

The first 2 were errors I got BEFORE resetting the system.

The last one is a battery state snapshot.

There are a couple that stand out to me:
#13 and #14. When I plug that code into alldatadiy, there's an interesting article about fleet vehicles with add-ons causing issues including battery drain... hmmm. My truck was "corporate owned" according to carfax, and there are holes and such in the headlights where flashers used to be.

Known Symptoms (not specific to any one device)

• The radio may not shut off after shutting down vehicle.
• Bus or LAN traffic may stay active leading to a discharged vehicle battery.
• Problems reprogramming modules either because of interference or the device will not allow the bus to power down.
• ONSTAR® may lose the ability to provide diagnostic data.
• Various engine and transmission performance issues with SES light set.
• Intermittent driveability issues.
• Reduced power message and codes.
• Stabilitrak® message and codes.
• C0561 stored in the EBCM leading to a traction control issue.
• No high speed LAN communication along with various communication U-codes.
• Transmission may not shift for one key cycle (TCM in default mode).
• Erratic gauge readings or flickering displays.
• SES, MIL or CEL light set and numerous DTC communication codes such as U0100, U0101, U186B and U1862.
• Diesel power-up devices causing no power in 4WD low range.
• Erratic electric power steering boost potentially associated with codes U2109, U2107, U2100, B1325, C0000.
• Battery run down
• Service Tire Pressure Monitoring (TPM) system light illuminated.
  – Cannot relearn TPM

However I cannot see anything that might relate to this under the dash...

#18 current no communication with TCM, but the other glaring issues at this point are gone due to the 'reset'.


The rest I am attributing to what I am terming "GSF" - General System Freakout

 

[gpracer1]

Just put a new battery in it already !!!

 

[TrybalRage]

Just put a new battery in it already !!!

I did. Two weeks ago. And topped it off before I installed it.

 

[intheburbs]

Have you tested the alternator beside just checking the voltage output with a multimeter? If it's not properly charging the battery, that would explain just about everything.