Not sure what connector he is using but we have never seen this issue with the ARB supplied connector using our harness when the ARB supplied connector is pinned correctly.
It looks like when you pinned the ARB side of the harness that comes unpinned you pinned it incorrectly. We found an install guide someone else created where they mention that you have to clip the ARB wires in yourself and the orientation they should be. Here is a screen shot for your reference.
It looks like when you pinned the ARB side of the harness that comes unpinned you pinned it incorrectly. We found an install guide someone else created where they mention that you have to clip the ARB wires in yourself and the orientation they should be. The link is below for your reference...