Whenever a vehicle is jump started, precautions must be followed in order to prevent the possibility of personal injury. Remember that batteries contain a small amount of explosive hydrogen gas which is a by-product of battery charging. Sparks should always be avoided when working around batteries, especially when attaching jumper cables. To minimize the possibility of accidental sparks, follow the procedure carefully.
Vehicles equipped with a diesel engine may utilize two 12 volt batteries. If so, the batteries are connected in a parallel circuit (positive terminal to positive terminal, negative terminal to negative terminal). Hooking the batteries up in parallel circuit increases battery cranking power without increasing total battery voltage output. Output remains at 12 volts. On the other hand, hooking two 12 volt batteries up in a series circuit (positive terminal to negative terminal, positive terminal to negative terminal) increases total battery output to 24 volts (12 volts plus 12 volts).
The GM W-Body vehicles have a number of sophisticated electronic systems and several sensitive on-board computers that can be damaged and are expensive to replace. Follow this factory procedure to avoid vehicle damage. In addition, the battery on most of these vehicles is usually hidden by other components, usually the windshield washer reservoir. For that rear, a remote battery positive terminal is provided.
- Position the vehicle with the good battery so that the jumper cables will reach, but do not let the vehicles touch. Be sure the jumper cables are in good condition and do not have loose or missing insulation.
- Turn the ignition switch to the OFF position. Turn all lamps and electrical loads on both vehicles off. Note that the hazard flashers and any lamps needed (underhood light, etc.) should be left on as needed.
- Apply the parking brake on both vehicles. Verify that the automatic transaxle is in PARK. The vehicle with the good battery should also be in PARK, or NEUTRAL, if a manual transmission.
- Check the built-in hydrometer "eye" (factory-type battery). If it is clear or light yellow, replace the battery.
- On these vehicles, a remote positive stud is provided for jump starting. This is much more convenient, and safer, than trying to get a jumper cable on the small side terminal bolt head at the battery, especially when it is hidden by another underhood component. The remote positive stud is covered by a red plastic flap and is located near the underhood electrical center. Clamp one end of the first jumper cable to the positive terminal remote stud. Making sure the jumper cable does not touch any other metal parts, clamp the other end of the same booster cable to the booster battery positive terminal (or its remote stud, if so equipped). NEVER connect positive to negative.
- Clamp one end of the second cable to the negative terminal of the booster battery. Make the final connection to a solid engine ground (metal bracket on the engine, etc.) at least 18 inches from the discharged battery. Make sure the cables are not on or near pulleys, fans or other parts that will move when the engine is started.
- Start the engine of the vehicle with the good battery. Run the engine at a moderate speed (approximately 1500 rpm) for several minutes. Then, start the engine of the vehicle which has the discharged battery.
- Remove the jumper cables by reversing the above sequence. Remove the negative cable from the vehicle with the discharged battery first. While removing each clamp, take care that it does not touch any other metal surfaces while the other end remains attached.