I will be straight up honest with you, i just tried taking the battery from my girlfriends car which is a fort escort, and installed it onto her 92 sc400. Well i didn't realize the battery from the ford had opposite battery terminals so i connected positive to negative vice versa onto the lexus. Saw huge sparks heard a little pop followed by a louder popping noise. The first pop came from the main fuse in the engine bay going out.. and i believe the second loud "popping" noise was the in the general area of the alternator but im not positive on that because i replaced the fuse which was a 20, and when i go to turn the key to ignition i still have no power running to it. Im stumpt and i could use a second opinion on this.
My car has an automatic transmission.
When hooking up the battery cables backwards, the polarity of the voltage is reversed and will cause the fuses to pop, the alternator to burn out the regulator, and the computer (ECM) will burn up the ground circuit inside the housing of the computer. There also could be an inline fuse in the ignition circuit that was burnt during the battery hookup. I recommend seeking out a professional, such as one from Your Mechanic, to help you troubleshoot your electrical system to see what all has failed.
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