How to Jump Start a Double Battery on a Diesel Tractor

Place the red cable clamp on one end of the jumper cables onto the positive battery terminal on one of the tractor's batteries. It does not matter which battery you choose to jump since power passes through both batteries.

Place the black cable clamp from the same end of the jumper cables onto a piece of bare grounded metal on the tractor's chassis. If you cannot find or reach any bare metal with the cable clamp, you can place the clamp on the negative battery terminal on the same battery as you placed the red cable clamp.

Place the red cable clamp on the other end of the jumper cable onto the positive terminal of the charged 12-volt battery, such as a truck battery.

Place the black cable clamp from the same end of the jumper cables onto a piece of bare grounded metal on the truck's chassis. If you cannot find or reach any bare metal with the cable clamp, you can place the clamp on the negative battery terminal on the battery.

Start the truck, and allow it to run at an idle for approximately five minutes. This will charge the batteries on the tractor enough to turn it over.

Start the tractor while the batteries on the tractor are connected to the battery on the truck.

Remove the negative battery cable from the truck, and then remove the red cable clamp from the truck's battery. Remove the negative battery cable from the tractor, and then remove the red cable clamp from the tractor's battery.