I was thinking along the lines of admranger...but waited to say anything since my e53 experience is only 2 yrs old.
I know the e38/e39 models have a high amp fuse distribution center located below the front passenger seat...but the e53's high amp fuse center is were admranger mentioned. I also have a diagram of the positive battery cable run...and it doesn't list anything below the front passenger seat for the e53...but again, I held off because I didn't want to say yes or no when I wasn't certain.
So take this info for what it is...if someone knows for sure there is a fusible link located there...please chime in...but the diagram below doesn't show the battery positive cable running to that area...and it would need to if there were fusible links located there:
e53 X5 positive battery cable run throughout the vehicle
