26 thoughts on “SOLVE A LOW VOLTAGE ISSUE!”

  1. If you think its the fans, then just disconnect them temporarily and check guage. Also if you blow a 40 amp fuse, thats a hugh fuse to blow, I would re check all wiring to make sure nothing is grounding out on the wiring. But first disconnect and see if it corrects.

  2. I would check to see if your truck has a voltage regulator, then check your alternator remove one of the batteries and see if it stays on and check for voltage right there

  3. a pwm pulse width modulator could help… decreasing fan speed at idle and increasing fanspeed with motor rpm… but then you would want a failsafe switch or dial to override it when traffic is jammed up.

  4. Maybe u need a bigger alternator. Imo the Alternator is not keeping up. Something could be wrong with the voltage regulator on the Alternator. An Alternator test isn't 100% reliable either especially if the problem is intermittent. What I've learned over the years is to take Alternator tests with a grain of salt. There could be a problem with it and you might not see it even using a tester it may appear to check out fine when actuality it doesn't.

  5. The distribution box has corrosion on the plate where the relays and fuses are. I lot of time win a vehicle goes through a car wash or some times the engine is washed liquid gets in the distribution box. Over time corrosion interferes with the electrical. You can take apart the distribution box and clean those parts or replace the hole distribution box.

  6. You are drawing more power than the alternator is producing at idle.There are several solutions to this.
    1 add a second battery in parallel. It will still drop at idle but it will take longer to happen. The battery drains down and then power drops.
    2 put a smaller pulley on the alternator. It will spin faster at idle. It will also spin faster at high rpm so be careful/
    3. run fans in stages. One fan on constant with AC – both fans with engine heat. This can be done with relays. The truck wont run too cool (with both fans on) and it will give the alternator a break more often when only one fan is on.
    4 larger alternator
    5 larger wire from alternator to battery (more efficient less resistance) also make sure ground is robust.
    6 resistor block on fans. they will run a bit slower but also draw less power.
    7 higher idle speed, an idle up solenoid when the fans are on.

  7. Mine os bone stock and I have same problem been through 2 alternators they are good everything else seems to be good but it's causing problems at idle we have a power inverter and it beeps and struggles to charge phones and stuff at idle everything seems under powered a little bit but it starts every day but every vehicle I've had hovers around 14v all day in gear and when it's on a full load with everything on its charging at like 12.8 to 13v that just isn't enough too me

  8. I have a 2000 Chevrolet C 2500 with a 5.7 and I’m having the same problem. I have replaced the battery and I have replaced the alternator a recondition alternator and it’s doing the same thing so I took the recondition alternator and it still does the same thing just for no reason devoted will jump to 1516 then drop down so low and shut my truck off and kill the battery when you get tested at parts store they tell you the alternator is bad so I replaced it with a metal one and staying at 12 V. I haven’t went very far yet and turn on the AC. It did not drop. The voltage but the truck was doing this when I bought it so I’m going to try a brand new alternator they did tell me that there are different temperatures alternators they can be put on that truck. I’m at 104 A they do sell one there’s 140 amp.

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