How to Jump Start a Diesel Truck with 2 Batteries

It is very frustrating when you turn the key to crank your vehicle and nothing happens. A dead battery never seems to occur when you have nothing to do and are surrounded by family and friends who are ready and able to jump start your car for you. A dead battery occurs when you are away from home, totally alone, or in a major hurry to go somewhere, like work.

If you drive an ordinary vehicle that is gasoline powered and cranked using only one battery then jump starting your vehicle is pretty easy to do, but what about when you drive a vehicle that is diesel powered and has two batteries? Diesel engines require a lot more cranking power so does this make a difference if you are getting a jump start from a friend or you are using one of the jump starters that you can carry around with you?

It is possible to crank a dual battery vehicle using a single battery truck if you follow the right steps to maintain the integrity of both vehicles.

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Jumpstarting Do’s

  • Turn on the heater in the vehicle that has the dead battery because this will protect the electrical system of the vehicle in case a surge of voltage is sent through the battery during the jumpstarting process
  • Have a wire brush handy to clean the battery terminals or connections if they are corroded
  • Read your owner’s manual to determine if your car has “jump start lugs”
  • Position the cars so that the jumper cables can easily reach both batteries but do NOT allow the two vehicles to be touching
  • Verify the battery voltage of both vehicles prior to connecting the jumper cables
  • Make sure that both of the vehicles are in the park and have their parking brakes set
  • Do wear protective eyewear if it is available to you
  • Do wear rubber gloves if there are any available to you

Jump Starting No-No’s

  • Do not smoke while you are connecting the jumper cables to either vehicle
  • Do not jump start a battery that is cracked or leaking any fluids
  • If the temperature is below freezing and there is a possibility that the fluid in the battery is frozen do not attempt to jumpstart it
  • Do not lean your body or face over the batteries of either vehicle
  • Do not “gun” the engine of the car providing the jump or rev the engine of the car providing the jump up by pressing on the accelerator
  • Never allow the ends of the jumper cables to come into contact with each other
  • Always check your connections twice before you begin to jump off the cars

Jumpstarting Step by Step

  1. Place the vehicles in park
  2. Raise the hoods
  3. Turn the heater on in the vehicle with the dead battery
  4. Make sure the radio, lights, and all other electronic components in the vehicle with the dead battery are turned off
  5. Turn off the radio, headlights, and unplug cell phone chargers on the vehicle that is providing the jump
  6. Turn the engine off on the vehicle that is providing the jump
  7. Check the cables that are connected to the two batteries on the disabled vehicle. If one of the batteries has thicker cables connected to it then this is the battery that you will connect via the jumper cables. If both of the batteries have cables of the same diameter then you may connect the jumper cables to either battery
  8. Connect the jumper cable that has a red clamp to the positive terminal lug on the battery of the disabled vehicle. The positive terminal should have a red cap covering it or you will see a + sign next to the terminal.
  9. Now connect the opposite end of the positive jumper cable to the positive terminal of the vehicle that has a charged battery
  10. Connect one end of the negative cable of the jumper cables to the negative terminal of the car that has the charged battery
  11. Connect the other end of this cable to the negative battery terminal of the dead battery, or you can connect this cable to any metal portion of the vehicle that is unpainted.
  12. Start the engine of the car with the good battery
  13. Start the engine of the vehicle with the dead battery
  14. Allow the batteries to remain connected for ten to fifteen minutes so that the dead battery can receive a proper charge from the hot battery
  15. Turn the engine off on the vehicle that has a hot battery
  16. Do not turn off the engine of the car that just had to get a jump
  17. Disconnect the negative jumper cable end from the car with the dead battery
  18. Disconnect the positive cable ends from the car with the dead battery
  19. Disconnect the positive cable ends from the car with the hot battery
  20. Disconnect the negative cable ends from the car with the hot battery



Allow the battery that just received the jump start to remain in a parked car with the engine running for fifteen to thirty minutes before you try to drive it, or before you do things like turn on the headlights, the radio, or anything that requires some of the electrical power to operate.

Remember that jump starting a car will get you back on the road but it should be a warning sign that causes you to go immediately to a mechanic to determine whether you need new batteries, or what caused the battery to fail you. A jump start is a band-aid, not a miracle cure and if you simply drive off there is a great chance that your car will not start the next time you try it.

Signs your Battery Needs Replacing

Pay attention to how your car responds when you are trying to crank it and you will often see the signs of a car that has a battery that is getting weak or needs replacing. Some of the most common signs of a weak battery that needs replacing are:

  • You cannot crank the car without depressing the gas pedal and giving the engine a little gas
  • Your engine sounds sluggish
  • Your car starts to backfire when you crank it
  • You hear a clicking sound when you turn the key

1 Comment
  1. Reply
    John Julian Pechacek September 29, 2021 at 3:48 am

    1) You need 2 sets of jumper cables and two vehicles with 12V batteries.
    2) Connect red & black of one jumper cable to vehicle1
    3) Connect red & black of the other jumper cable to vehicle2.
    (now you have 4 leads to connect to the 24 volt Vehicle)

    4) Connect vehicle1 red to red on dead 24V battery.
    5) Connect vehicle2 black to black on dead 24 battery.
    6) Connect the remaining black and red together.
    (This connects the black of vehicle1 to red of vehicle2)

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    Mighty Trucker