Not the pos , the negative always disconnect the negative to avoid touching the wrench to ground and causing a spark, which could cause a big boom!!!

 

In all of my years of changing out batteries, I always disconnected the positive. I thank you for the learning experience.

"Today was not wasted.... I learned something new."

 

(It's in the Owners Manual)

 

And shorting out the positive terminal with a wrench will result in a red-hot wrench before you can drop it. Mind you, having "nO-panS" branded into ones palm might be "cool" to some. :)

 

Blisteringly funny Whopper ! Yes pun intended! I had experience with a new mech back in the day , I was assigned to show him the ropes on the lube rack.
A car came in, he was fine with the oil and filter, grease but the battery clean was a blast! After I instructed him to disconnect the battery terminals to clean them he got confused and went to the positive first sparked the wrench against the rad cradle and the fumes from the battery blew up ! He wasn't injured but needed fresh underwear!!!

 

THE BAD: Do you still have the protective RED COVER on the positive terminal under the hood? If NOT- has the top computer module next to that terminal been moved around? If that computer module has been moved & touched the terminal-it will cause the symptoms that you have described.
THE GOOD: You can get another computer module at the junk yard for cheap & it DOES NOT need to be reprogramed by the dealer. Just make sure you DISCCONECT THE BATTERY AT THE TRUNK AREA FRIST-BEFORE CONNECTING THE COMPUTER.

 

& don't close the hatch with the battery disconnected ! Or you'll be searching for "How to manually open the rear hatch" thread (bit of a PITA, but doable)

 

TRUE THAT!

I layed a folded towel over the lock.

 

Good tip and an easy solution to what can turn into a very frustrating situation.

 

Make SURE it's an old, scruffy towel, or Momma won't be happy & when Momma Ain't Happy, NOBODIES happy !