alternator putting out 16 volts

Discussion in 'Volvo Forum' started by ecook74, Dec 29, 2020.

  1. ecook74

    ecook74 Bobtail Member

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    Aug 31, 2017
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    Good evening all. My 2007 Volvo is putting out 16.1 volts at times and the "light control module is in high voltage mode" indicator comes on. And a message about the fog light comes on as well but the fog lights are unplugged. The alternator is a 3 wire 34si so I cant run a jumper wire. Any suggestions on what to do? I have cleaned all grounds and terminals.
     
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  3. AModelCat

    AModelCat Road Train Member

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    Get the multimeter out and start diagnosing.

    I'd start with checking the voltage right at the alternator and then right at the batteries. Should be very minimal difference between the 2.

    I'm not the most experienced with Volvo but a lot of newer trucks have a remote sense wire that runs from the alternator to the batteries. If you've got that wire I'd check it too since a poor connection on that wire can fool the alternator into thinking the batteries have low voltage.
     
    Shawn2130 Thanks this.
  4. salim patel

    salim patel Bobtail Member

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    I had same problem with 2007 Volvo few years back I ended up changing the cluster .the gauge on deshbord went bad if u check voltage at aulterneter it will be correct.
     
    loudtom Thanks this.
  5. ecook74

    ecook74 Bobtail Member

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    Thanks for the repiles
     
  6. bad-luck

    bad-luck Road Train Member

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    Sounds like the voltage regulator in the alternator went bad, and you need a new alternator. Check the output at the alternator, if its 16 then the alternator is your problem.
     
  7. ecook74

    ecook74 Bobtail Member

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    Aug 31, 2017
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    When I check the volts at the alternator it reads good(13.8 to 14.2). But thats the same reading on the dash at that time. I try to pull over and check the alternator everytime it goes high on the dash but by the time I get under the hood, the volts start to drop. It the regulator is bad, should I get a bad read from the alternator all the time?
     
  8. salim patel

    salim patel Bobtail Member

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    Change or repair instrument cluster your problem will be solved.i suggest u u buy new deshbord from Volvo dealer. It will outlast your trk. Repair will not guarantee . because other things will go wrong with it buying used same problem.cluster gauge gone go on you tube u will find video on how to repair replace it
     
  9. ecook74

    ecook74 Bobtail Member

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    OK thank you salim patel
     
  10. vangtransport

    vangtransport Heavy Load Member

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    Are you setting the RPMs higher when you're parked to try & duplicate your RPMs when driving?
     
  11. ecook74

    ecook74 Bobtail Member

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    Aug 31, 2017
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    Yes I am raising the RPMs while parked but the volts doesn't go high on the dash or at the alternator. The volts are between 13.8 and 14.2. The volts only move to 15 and 16 while driving.
     
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