Emergency Starting With Jumper Cables
When using jumper cables, follow the instructions below.
Warning: Batteries release explosive gas. Do not smoke when working around batteries. Put out all flames and remove all sources of sparks or intense heat in the vicinity of the battery. Do not allow the vehicles to touch each other. Do not lean over the batteries when making connections, and keep all other persons away from the batteries. Failure to follow these precautions could lead to severe personal injury as a result of an explosion or acid burns.
Notice: Make sure both starting systems have the same voltage outputs, and avoid making sparks. Otherwise the vehicle charging systems could be severely damaged. Also, do not attempt to charge isolated, deep-cycle batteries with jumper cables. Follow the battery manufacturer's instructions when charging deep-cycle batteries.
Note: On vehicles equipped with an optional jump-start post, attach the positive cable clamp to that post instead of to the battery.
- Apply the parking brakes and turn off the lights and all other electrical devices.
- To gain access to the batteries, open the battery compartment. See Fig.. For detailed instructions, see Cab Door Locks and Handles.
- Connect an end of one jumper cable to the positive terminal
of the booster battery (or jump-start post if equipped), and connect
the other end of the cable to the positive terminal of the discharged
battery (or jump-start post if equipped). See Fig..
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Top Step
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Battery
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Cab
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Battery Access Door
Fig. 1, Battery Compartment, Open
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To Ground
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3rd
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To Frame (ground)
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4th
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To Starter
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2nd
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1st
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Booster Battery
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Discharged Battery
Fig. 2, Jumper Connections
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- Connect one end of the second jumper cable to the negative terminal of the booster battery, and connect the other end of the cable to a ground at least 12 inches (300 mm) away from the batteries of the vehicle needing the start. The vehicle frame is usually a good ground. Do not connect the cable to or near the discharged batteries.
- Start the engine of the vehicle with the booster batteries, and let the engine run a few minutes to charge the batteries of the other vehicle.
- Attempt to start the engine of the vehicle with the batteries receiving the charge. Do not operate the starter longer than 30 seconds, and wait at least two minutes between starting attempts to allow the starter to cool.
- When the engine starts, let it idle a few minutes.
- Disconnect the grounded cable from the frame or other non-battery location, then disconnect the other end of the cable.
- Disconnect the remaining cable from the newly charged battery (or jump-start post if equipped) first, then disconnect the other end.
- Close the battery compartment. For detailed instructions, see Cab Door Locks and Handles.
Notice: Always connect the battery, jumper cables, and charger correctly (positive-to-positive and negative-to-negative). Connecting a charging device backwards (positive-to-negative) will blow fuses that power the bulkhead module (BHM) and chassis module (CHM), and the devices they control will not work.
Warning: Do the next step exactly as instructed and do not allow the clamps of one cable to touch the clamps of the other cable. Otherwise, a spark could occur near a battery, possibly resulting in severe personal injury from explosion or acid burns.
Warning: On vehicles with Mercedes-Benz AGS transmissions, make sure the current gear indicator displays "N" before starting the vehicle. If the transmision starts in gear, it could cause an accident resulting in death, serious personal injury, or property damage.
Warning: Do the next step exactly as instructed and do not allow the clamps of one cable to touch the clamps of the other cable. Otherwise, a spark could occur near a battery, possibly resulting in severe personal injury from explosion or acid burns.