Last week I installed an intercooler. During the install I removed and reinstalled the ground wire on the passenger side frame below the engine fuse box. I started to get weird random issues. ABS/TC lights on/off. Random hard starting. RPM gauge drop out (thought is was CPS first). Door locks randomly locking/unlocking. Key Fob randomly not working. Radio turning on and off. The whole dash turning on and off or flickering. Basically as if my car was possessed. Battery and alt tested good. Removed all the battery cables (including my 2 extra ground to alt mount and pos to alt), cleaned every connection, and reinstalled. Every issue went away.
I am 99% certain the bad connection was the ground wire from battery to frame that caused it. It was rusty....I was lazy.... Didn't clean prior to reinstall.
If your car every acts possessed check your grounds!
