Charging system

[h1000101b]

So that you know 2015 Silverado 2500/3500 (FOR SURE) DONT Have this weird charging system. ("current sensor Loop") as it is defined by GM. FOLLOW THIS LINK IT WILL TELL YOU ALL ABOUT IT.

 

The videos are full of great information and also there's a link to a PCM module to bypass this system for those of you that have it. (From what I know.. NO 2500/3500 have it... at least 2015 and under don't ... can't really speak for the rest)

 

https://www.diymobileaudio.com/threads/do-i-need-an-additional-battery-i-already-have-2-something-isnt-adding-up.438382/#post-5944210

 

AND.. You're Welcome !

[Killcam727]

Hello my 5.3 has 54000 miles currently.When I got the truck it charged normal at 14.7v then would drop to 12.5 when the computer felt the battery had good charge. all the sudden  it started charging at 15.9 and drops to 13.9 or 14 does anyone know why? I put a brand new battery in it also.

[shakenfake]

That is normal operation

[Killcam727]

11 minutes ago, shakenfake said:

That is normal operation

Thanks for the reply can you explain why when I got the truck it went from 14v to 12v but now it’s going from 15.9 to 14 never dropping to 12.9 
 

[shakenfake]

It could be because of the new battery. Someone else may explain how the system works better than I but I believe that would be the cause of it.

[Killcam727]

Thank you 

[JimCost2014]

40 minutes ago, Killcam727 said:

Thanks for the reply can you explain why when I got the truck it went from 14v to 12v but now it’s going from 15.9 to 14 never dropping to 12.9 
 

15.9 sounds very high.

 

Are you just going by your dash gauge, or using a scan tool to get that number?

[Killcam727]

Multimeter

[Killcam727]

Just now, Killcam727 said:

Multimeter

Only thing I could find is there is like 7diffrerent charging modes for this system and the one matching the reading I’m getting is for freezing temps well I live in central Fla so I know it’s not that cold

[Not very reliable truck]

Does my 2017 Silverado 1500 LTZ have an internal or external voltage regulator? Is the voltage regulator covered under the GM Powertrain warranty?

[cfell]

Agree to previous comments and thanks for the detailed Electrical operation.

 

All voltage references in this post are positive VDC unless noted otherwise.

 

2017 having some “strange, transient”” issues”… it “seemed” the problem is electrical…voltage when off, measured at batteries was 12.4 or so.  When running, voltage would “creep up” to around 14.7 then reduce to 13.8 all measurements by VOM meter… or OBDII port. Based upon above description of electrical system, things seemed ok… then I noticed the voltage meter in the DIC was gradually showing lower voltage, just over 13VDC.  March 2021 replaced the batteries.  AGM.

 

Truck stopped having most of the problems I was perceiving.  Until September, 2022, 17 months into the new batteries life.

 

I had seen the voltage dropping lower and lower, over several months, slightly below the near 14 normal.  This would hold fairly steady while driving… something 200miles between key cycles.  Clearly the original “charging / electrical system” was slowly dropping hints.  I kept a wary eye on the gauge as the “transient” electrical gremlins worked their deeds.

 

On Monday 26SEP2022, I was under the hood checking fluids and cable connections, hoses, etc. I observed at that time that the “Cell Seal plugs” on the AGM battery were pressing up against the plastic label which helps retain the seal and prevent overflow.  
 

I found both batteries had these “protruding” seals on some of the cells, other cell plugs were fully seated.   Having a physical inspection done at the store where purchased they confirmed the batteries were failing. I drove home so the truck would not be disabled where it might get towed.

 

I removed the batteries correctly, transported, swapped then returned and installed the “new” batteries. NOTE: once removed, the batteries had discernible “bowing outward” of the case walls.. a sign of possible internal battery issue.  New batteries case sides were straight.
 

When I tapped the negative terminal to the battery there was a strong “electrical pop” sound … one time. While cleaning and applying very light dielectric to the connectors, I completed install of all cables.

 

Static voltage 12.5 by VOM.. hmm… truck key in, voltage held after KEY RUN.  DIC was approximately correct.

 

KEY Start, fired better than before and settled to nice idle.. better..!!! (noT my imagination.)

 

Voltage climbed to over 14 gradually, settling around 14.5.. (DRL on), AC, radio, all powered on…good.

 

Took my Bride in the truck for a 35 minute ride then a stop for 15 minutes…voltage 12.6… another drive for 5 miles and 30 minute stop. Volt gauge at 12.6 and to just over 14.4 when running dropping to 14.2 in 35 miles home. Voltage around 12.7 last night and this morning.

 

This morning check showed static 12.8, truck start clean and showing slightly over 14 after a few seconds.  This delay was explained one time as normal as the electrical system was monitoring while gradually increasing voltage.

 

I checked with VOM at 14.2 then down to 13.4 then up to 14.5 where there were slight fluctuations of about 0.8 volts for 2 minutes, settling at 13.7 +-0.09 for 3 minutes then shutdown.

 

NOTE: the voltage remained within .05 when I transmitted on my mobile amateur radio… with no other symptoms presenting.. (this was also under a metal roof building.. so plenty of possible errant RF induced behavior.)

 

NET:

1- get and learn a VOM

2- monitor gauges well

3- know your truck voltage via the VOM!!! The “gauge” is an appropriate and provided by the ECM… “Trust but Verify”

4- pop the hood and check your batteries.. (at least we can do that for now… wait until the “car batteries” start popping off)1

 

peace..

[GMCustomerService]

On 9/28/2022 at 5:06 PM, cfell said:

Agree to previous comments and thanks for the detailed Electrical operation.

 

All voltage references in this post are positive VDC unless noted otherwise.

 

2017 having some “strange, transient”” issues”… it “seemed” the problem is electrical…voltage when off, measured at batteries was 12.4 or so.  When running, voltage would “creep up” to around 14.7 then reduce to 13.8 all measurements by VOM meter… or OBDII port. Based upon above description of electrical system, things seemed ok… then I noticed the voltage meter in the DIC was gradually showing lower voltage, just over 13VDC.  March 2021 replaced the batteries.  AGM.

 

Truck stopped having most of the problems I was perceiving.  Until September, 2022, 17 months into the new batteries life.

 

I had seen the voltage dropping lower and lower, over several months, slightly below the near 14 normal.  This would hold fairly steady while driving… something 200miles between key cycles.  Clearly the original “charging / electrical system” was slowly dropping hints.  I kept a wary eye on the gauge as the “transient” electrical gremlins worked their deeds.

 

On Monday 26SEP2022, I was under the hood checking fluids and cable connections, hoses, etc. I observed at that time that the “Cell Seal plugs” on the AGM battery were pressing up against the plastic label which helps retain the seal and prevent overflow.  
 

I found both batteries had these “protruding” seals on some of the cells, other cell plugs were fully seated.   Having a physical inspection done at the store where purchased they confirmed the batteries were failing. I drove home so the truck would not be disabled where it might get towed.

 

I removed the batteries correctly, transported, swapped then returned and installed the “new” batteries. NOTE: once removed, the batteries had discernible “bowing outward” of the case walls.. a sign of possible internal battery issue.  New batteries case sides were straight.
 

When I tapped the negative terminal to the battery there was a strong “electrical pop” sound … one time. While cleaning and applying very light dielectric to the connectors, I completed install of all cables.

 

Static voltage 12.5 by VOM.. hmm… truck key in, voltage held after KEY RUN.  DIC was approximately correct.

 

KEY Start, fired better than before and settled to nice idle.. better..!!! (noT my imagination.)

 

Voltage climbed to over 14 gradually, settling around 14.5.. (DRL on), AC, radio, all powered on…good.

 

Took my Bride in the truck for a 35 minute ride then a stop for 15 minutes…voltage 12.6… another drive for 5 miles and 30 minute stop. Volt gauge at 12.6 and to just over 14.4 when running dropping to 14.2 in 35 miles home. Voltage around 12.7 last night and this morning.

 

This morning check showed static 12.8, truck start clean and showing slightly over 14 after a few seconds.  This delay was explained one time as normal as the electrical system was monitoring while gradually increasing voltage.

 

I checked with VOM at 14.2 then down to 13.4 then up to 14.5 where there were slight fluctuations of about 0.8 volts for 2 minutes, settling at 13.7 +-0.09 for 3 minutes then shutdown.

 

NOTE: the voltage remained within .05 when I transmitted on my mobile amateur radio… with no other symptoms presenting.. (this was also under a metal roof building.. so plenty of possible errant RF induced behavior.)

 

NET:

1- get and learn a VOM

2- monitor gauges well

3- know your truck voltage via the VOM!!! The “gauge” is an appropriate and provided by the ECM… “Trust but Verify”

4- pop the hood and check your batteries.. (at least we can do that for now… wait until the “car batteries” start popping off)1

 

peace..

This is certainly not what we like to hear, cfell.  Please know, customer satisfaction is extremely important to us. Our team would be more than happy to take a closer look into the concerns with your truck. To do so, please send an email to [email protected] with ATTN: cfell/GM Trucks in the subject line.

Please include your contact information, VIN, a brief description of your concern, and the name of your preferred dealership. We look forward to hearing from you. To learn more about GM’s privacy policy, please visit https://www.gm.com/privacy-statement.html.
 
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