Bad grounds do not cause batteries to go dead - too much current causes them to go dead. The ONLY way to diagnose a battery drain is to MEASURE the drain and know what you are chasing. In doing so, you often find other issues because defective modules or improperly installed aftermarket crap will often cause excessive battery drain. So, chasing a battery that is going dead can pay dividends with a car that you don't know the history of.

We are pretty good at helping people with their Crossfire when they have had the car some time and something comes up. But with a "problem child", that is, a car just bought with an unknown history and verified problems, you better be willing to WORK and LEARN. And keep in mind, YOU will be working harder at this than we do because we are not there - who the hell knows WHAT was done to that car? You cannot even assume its' all factory or stock. And we sure has hell have no way of knowing.

First thing I'd do, is chase what is drainging the battery - and KEEP IN MIND, you may find more than one item doing so.

I went to great trouble to provide us all with a Crossfire-specific procedure that addresses everything I could think of. THere are two versions, one for those experienced in this work(V1), and one for everyone else(V3).
If you take your time, you can get thru this. If you are going to try to cut corners, dont even bother, push the car off a cliff, life will be easier.

Go here, links to downloads are in Post #1:
https://www.crossfireforum.org/forum...lp-papers.html