Need help, not charging house batteries

[Joe Hogan]

Commonly referred to as a BIM or BIRD. It is a bidirectional relay that manages the draw of the house batteries on the Alternator. Also manages the draw on the chassis battery when parked.

 

[Joe Hogan]

Here are a couple of images that might help.

First is a battery connection chart posted above the chassis battery.

Next is the main chassis fuse box in the engine bay. Note in the upper left corner you can just make out the Bi-Directional Relay tucked away in the fuse box.