How to Jump Start a 1990 535I BMW

1.
Try the ignition first to troubleshoot the battery.
Determine that the battery is the reason the engine won't start. Turn the ignition. If the engine cranks, the battery is good. If there's silence or a ticking sound, the battery is faulty.
2.
Attach the positive clamps first.
Turn the ignition off. Lift the hood of both vehicles. Locate the positive post under the hood of the BMW 535i. It connects to the clamp of the positive (red) cable. Attach the clamp on the other end of the red wire to the positive terminal on the booster vehicle.
3.
Attach the negative terminals last.
Attach the negative (black) clamp to the negative terminal of the booster battery. Attach the other negative clamp to the engine frame of the BMW to complete the circuit. Any unpainted metal surface will suffice. Just make sure it's away from any moving parts.
4.
Run the booster cars' engine for a few minutes before trying to start the BMW.
Start the engine of the booster vehicle. Wait at least 5 minutes for a charge to build up. Start the BMW. If it starts, move on to the next step.If it fails to start, wait another few minutes and try again. If the car still fails to start after 30 seconds of trying, call a professional mechanic. The battery might not be at fault, and further tries could damage your engine.
5.
Remove the cables in reverse order.
Remove the cables in the reverse order they were attached: the BMW engine frame first, and the booster battery's red terminal last.
6.
Charge the battery for at least 12 hours.
Drive the BMW to a location where you can safely remove the battery and attach it to a battery charger for at least 12 hours. The vehicle's alternator will provide some charge to the battery as you drive, but this is not its primary function.