How to Check for Bad Positive Battery Cable in a 1989 Benz 560SL

1. Remove the negative battery cable connector from the negative battery terminal by loosening the bolt that secures the connector to the terminal, then pull upward on the connector. Push the negative battery cable to the side so it cannot touch the battery terminal.
2. Place one end of the battery jumper cable onto a metal part of the engine bay. The inner fender liner is a good location because no electricity runs through it. Do not connect the jumper cable to anything with electricity running through it. If a ground is connected to anything with electricity, you risk shorting out the electrical system of the vehicle.
3. Place the other end of the battery jumper cable onto the negative battery terminal. Battery jumper cables have two connectors on each end; one for the negative connection and one for the positive. Make sure the same color wire is used for both connections.
4. Attempt to start the Benz 560SL. If the vehicle starts normally, replace the negative battery cable. If the engine does not start, you have eliminated the negative battery cable as the issue.