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Alternator voltage 14.5

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Alternator voltage is at 14.5 both on the gauge and at the battery. Dealer said I need a new alternator but this one charges fine, just too high voltage. Both Batts are new. Can the PCM be adjusted or does it need replaced (ouch).
 
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Between this post and your other ones it REALLY Sounds like your dealership service manager just wants to charge you for throwing parts at your truck without actually diagnosing the problem.

While it is good that you are trying to learn more about your truck by asking questions here, it also sounds like you need to find another smarter and likely more honest repair shop.

That said, in order for members here to help out, you need to be MUCH more detailed in your description of the truck AND the description of the symptoms it is experiencing.

Firstly PLEASE fill out the year and fitment of your truck as well as its ownership history if possible

With the added details of your truck and symptoms we can offer you much more detailed answers as to what the problem and solutions might be…rather then just stabbing in the dark like your dealership seems to be doing
 
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Can the ECM be adjusted or does it need replaced (ouch).

The ECM does not regulate alternator voltage - it is done through the PCM.

There is a battery temperature sensor under the driver side battery that helps control the upper limit of the voltage regulator setting. Battery voltage at 14.5 volts on a 30° day COULD BE NORMAL. The same reading on a 80° day would be excessive. The dealer should and probably does know this.

I think it would be worth your time to look up a discussion overview of how a charging system works on your era of truck. There is good information here on the TDR regarding that subject, as well as on the internet. At minimum it would help you ask us or the dealer or any repair shop the right questions. It would also help put you at ease regarding what is normal and what is not normal.

- John
 
Between this post and your other ones it REALLY Sounds like your dealership service manager just wants to charge you for throwing parts at your truck without actually diagnosing the problem.

While it is good that you are trying to learn more about your truck by asking questions here, it also sounds like you need to find another smarter and likely more honest repair shop.

That said, in order for members here to help out, you need to be MUCH more detailed in your description of the truck AND the description of the symptoms it is experiencing.

Firstly PLEASE fill out the year and fitment of your truck as well as its ownership history if possible

With the added details of your truck and symptoms we can offer you much more detailed answers as to what the problem and solutions might be…rather then just stabbing in the dark like your dealership seems to be doing

Thanks for the reply. How do I create a signature with all my info? 2007 5.9 stock. BTW my scan tool shows target voltage 14.8. reading the older thread shown all of them have 14.5 to 15v. I guess I'm just old fashioned, looking for 13.8 to 14.2 like the old days.
 
@gcrockett, Upper right of the TDR page is your user name. Place cursor over over your name then go to personal details and fill out the info there. I would also suggest that you clean all connections on the batteries including crossover cable. Corrosion can cause higher voltage due to the resistance being created. Glad you want to learn about your truck. We're here to try and help you figure it out without draining your wallet!
 
Have seen everything from the Alternator from 13.3V at almost 120° up to 15.2V at -30°
Charging voltage is set by the ECM considering outside and battery temperature.
That's why you see such a wide range of voltages.

Your truck is perfectly working, no clue why a dealer wants to sell you an other Alternator.
 
Oh, and the gauge is fake more or less. It shows what the truck wants to show you. It is not hardwired to the battery.
So do not trust that gauge under any circumstances where you need to know exactly what's going on.
 
Sounds normal. Why do you think it’s not normal?

The ECM does not regulate alternator voltage - it is done through the PCM.

There is a battery temperature sensor under the driver side battery that helps control the upper limit of the voltage regulator setting. Battery voltage at 14.5 volts on a 30° day COULD BE NORMAL. The same reading on a 80° day would be excessive. The dealer should and probably does know this.

I think it would be worth your time to look up a discussion overview of how a charging system works on your era of truck. There is good information here on the TDR regarding that subject, as well as on the internet. At minimum it would help you ask us or the dealer or any repair shop the right questions. It would also help put you at ease regarding what is normal and what is not normal.

- John
No PCM on his truck. The ECM controls the voltage.
 
The On-Board Diagnostics (OBD) senses the charging system parameters and monitors for issues and sets a Diagnostic Trouble Code (DTC) for certain failures. If there is no indication of a problem by any of the gauges, the "check gauges" lamp, or stored DTC codes, and the battery is charging as expected, it is probably working fine.

Find a different dealer.
 
My bad - thanks for the clarification. That's what I get for not researching before I post.

- John
Well I didn't mean to start a fire here. ECU/ECM/PCM/ all refer to something I can't fix or adjust. However reading back over many old posts it seems 14.5+- at the batteries with my fluke meter is normal. I appreciate the help.
 
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