2014 Yukon Denali Alternator Question

Discussion in 'Engine & Drivetrain' started by Johnnyringo, Nov 4, 2016.

  1. Johnnyringo

    Johnnyringo Member

    Messages:
    14
    Likes Received:
    1
    I have a "new to me" 2014 Yukon Denali SUV with around 45K miles. I notice that quite often when the engine is started the volt meter shows what appears to be less than 13V. It continues that way for quite a while, then jumps up to 14+V. I stopped by the local dealer when it was showing the lower voltage reading and the service writer said "it's still in the safe zone". I'm not real comfortable with his explanation as every auto I've ever owned always runs closer the the 14V range.
    Any comments or suggestions?
    Thanks, JR
     
  2. DAlastDON

    DAlastDON Platinum Supporter

    Messages:
    4,686
    Likes Received:
    2,414
    Alternator charging is probably being turned off by computer. Less load on engine equals better efficiency. My 2008 envoy does this so your 2014 likely does too.
     
    littleblazer likes this.
  3. freddyboy61

    freddyboy61 Well-Known Member

    Messages:
    180
    Likes Received:
    42
    Totally agree with above, the PCM (ECM) controls alternator rate of charging. At initial engine start the alternator is commanded to hold back the charge rate.
     
  4. DocBrown

    DocBrown Well-Known Member

    Messages:
    375
    Likes Received:
    73
    No need to worry. My Sierra will often drop well below that even. When I start it, or when I'm cruising on the freeway at a constant rate.
     
  5. Sparky

    Sparky Moderator

    Messages:
    9,676
    Likes Received:
    4,754
    Alternators used to just be set to push 14V all the time, but more recently (in the last 10 years or so) they're controlling the output more. Part of it is to supposedly help not overcharge the battery. My 07 Silverado will drop it back to 13V regularly.
     
  6. Mooseman

    Mooseman Moderator

    Messages:
    7,989
    Likes Received:
    3,401
    I can attest to that. The 2015 Tahoe I drive at work is usually below 14V after startup.
     
  7. Johnnyringo

    Johnnyringo Member

    Messages:
    14
    Likes Received:
    1
    Thanks much to all for the replies. I appreciate it. I have to say I really like my Yukon. Took a 3,000 mile trip towing a trailer to pick up a "parts car" to finish my street rod. The 6.2L engine is impressive!

    BTW, I signed up for a monthly donation to the site. Does anyone know if it arrived? JR
     
    Last edited by a moderator: Nov 8, 2016
    xavierny25 likes this.
  8. kickass audio

    kickass audio Well-Known Member

    Messages:
    925
    Likes Received:
    286
    A lot of newer vehicles do that. I like my envoy as it's older and doesn't have the stupid ammeter that GM is using on the newer vehicles to monitor current on the vehicle's electrical system and the alternator is always at 14.6v or more depending on the temperature outside (it's usually at 14.9 or higher in the winter when it's really cold) and if i'm loading down the alternator with my sound system up high.

    The reasoning for it is to shut down the alternator so it doesn't drive a big load on the engine and make you suffer a loss on your MPG's. I can say that with my aftermarket alternator on my envoy that if I bump at idle the engine will surge up and down because of the load the alternator is placing on the engine.

    I personally think that the new style vehicles that let the voltage drop down lower is just making buyers blow money unnecessarily on batteries as a fully charged 12v battery should be at 14.4v and if you aren't charging at that value then your battery isn't fully charged but hey what's another charge for car owners!
     
  9. Sparky

    Sparky Moderator

    Messages:
    9,676
    Likes Received:
    4,754
    Actually, fully charged 12V lead acid battery is about 13.8V.
     
    m.mcmillen and littleblazer like this.

Share This Page