Hopefully I’m posting in the right spot been awhile since I’ve been here. I’m installing a system in my 2008 S550 Benz. I’m using a Lc2i Pro to planet audio bb2400.1 amp. I have a good ground and fused battery connection. I test my ground with a power probe it shows ground and I test my battery cable and also shows good 12+ volts. When I connect ground to amp, the ground reads as ground. When I connect the power(battery) cable to the amp the ground becomes a positive 7volts. I’ve tested my setup with another amp and same thing happened. So I put back my planet audio amp and it worked I was bumping but then the sub went boom boom and green light on amp was on but blue leds were not. I then supplied ground from the power probe to ground port with my ground wire on amp and everything worked and sub played again. I released ground with the power probe sub made sound and did a boom boom again and amp “ON” light was green and no blue leds again. I have no idea why battery voltage is showing on the amp ground side only when I connect the battery cable. But then I supply ground through power probe to my amp with the ground connected and it works like nothings wrong.