Charging issues

[Trider00]

I’m not completely up to date with the newer models but I am trying to get there. I have a 2017 silverado 1500 4x4 and I’m having some charging issues. I changed the alternator and battery both are new but the battery isn’t charging. I’ve tried replacing the wire between alternator and battery, checked wiring harness and wires. But it will not charge. Any help is appreciated. Also the old battery and old alternator tested good when pulled out of the truck and tested

[Yotaman]

How do you know the battery is not charging? truck won't crank or going off of dash gauge? System will show less than 14V if battery is charged just FYI.

 

Yotaman

[64BAwagon]

Check the battery with the truck off, it should show somewhere around 12.8 volts if its fully charged. 

The truck will not command the alternator to charge if it doesn not detect a need. This is to save energy.

When you state "charging issues" what exactly does that mean ? The volt gauge on the truck will waiver from 12v to 14 v depending on the load and need. Does the truck start properly ? Also check to make sure the amperage detector ring is still on the positive cable (if that year has one) Its a black plastic ring around an inch in diameter that is on the positive cable near the battery. 

 

 

[Trider00]

The days will pop up a charging system issue and the gauge doesn’t go above 11 volts. The other day I lost all my dash lights and my power steering and radio and then it died. The battery and alternator both test good off the truck but on the truck they both test bad. There wasn’t a ring on the battery cable when I got the truck

[It's Tim]

Is this a salvage vehicle?

Has it ever been in a flood?

[mjm-1957]

Get an accurate dvm and check alternator output right at the output terminal of the alternator and then check at the battery. Are they close? If not perform a voltage drop test on all battery cables.  Disable the fuel injectors and crank the engine while monitoring the voltage drop.Those are noted to have questionable battery cables. Gm doesnt want more than .5 voltage drop on the cables . We change a fair amount of them at work.Also that battery sensor is supposed to be on the negative battery cable. Ground connections are another constant source of problems. Loose or corroded grounds will drive you crazy.

[Trider00]

Thanks guys I will get to working on it after work and see where I get with it

[GMCustomerService]

On 11/14/2022 at 6:20 PM, Trider00 said:

I’m not completely up to date with the newer models but I am trying to get there. I have a 2017 silverado 1500 4x4 and I’m having some charging issues. I changed the alternator and battery both are new but the battery isn’t charging. I’ve tried replacing the wire between alternator and battery, checked wiring harness and wires. But it will not charge. Any help is appreciated. Also the old battery and old alternator tested good when pulled out of the truck and tested

This is certainly not what we like to hear, Trider00.  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 2017 silverado 1500. To do so, please send an email to [email protected] with ATTN: Trider00/GM Trucks in the subject line.

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[Trider00]

So I’ve changed just about everything including another new battery and alternator and cleaned all grounds then tried to run diagnostics test and can’t figure it out. Can anyone thing of anything else?

[movario]

I would start again from the beginning.

 

When increasing the rpm over 2500RPM is the alternator charging (tested directly with a voltmeter on the B+ terminal of the alternator)?

What voltage do you read on that terminal?

What voltage do you read if you measure the B+ terminal against the alternator case?

What voltage do you read if you measure the B+ terminal against Battery - ?

After that, I'd check the "D+" terminal. As this is probably a PWM signal, you should check that with an oscilloscope.

I'd double check ALL the fuses, maybe on died because of the old alternator.

 

You mentioned that you checked the wiring. How did you check it? Did you measure loss of voltage in idle and under load? A circuit that is fine under idle, can die under load.

[silveradosid]

check the plug on the ecm for corrosion