Hi i have a 2005 mercedes cl500 the battery was dead i try to jump it but i put the ps neg incorrectly so now i have no power only my radio turns on please help me
jump it properly
If you are lucky you may have burned out a master fuse or fusible link, though it's more likely the car's electronics have been fried. (It only takes a fraction of a second with reversed polarity and even 20 years ago Mercedes had a lot of electronics.)
The repair manual available at charm.li for your car may help.
Whenever I go to jump a car, I always go "positive to positive, negative to negative" exactly how Scotty does it. I also check each cable again before making the negative to negative connection to really ensure they are right. When you're dealing with cars' electronics, one miss-step could be a very costly mistake.
I'm assuming you oriented the cables on one car correctly and you accidentally flipped the positive cable to the negative cable on the other battery, likely a different make and model car. Hook up each cable "positive to positive, negative to negative" from now on, making the trip between the cars twice. You will give yourself ample time to notice any abnormality before you set the final cable up. Once you set that final cable up, there's basically no turning back. It must be right the first time.
@justin-shepherd Better yet, use a jump starter that has built-in polarity protection. I gave up on jumper cables years ago.
@chucktobias I always forget that they have those now.
6 months after I got my Mustang, someone's battery died at work and asked if I were willing to give that person a jump. I only agreed if I worked with the jumper cables myself. I've heard way too many horror stories of people messing up the polarities in the cables and frying all of their electronics. I wasn't taking any chances, haha.
@justin-shepherd Using the jump starter pretty much removes that risk. These days there are also jumper cables available that have built-in polarity protection.
I didn't know that one either, haha. I'm not in the habit of pushing my cars' batteries to the point where I'm always asking for a jump, though. Some people do it like no tomorrow.