[Compelica]

Possibly explains why the main body ECU has to be replaced when it comes to certain lights not working as it should:

https://www.ft86club.com/forums/show...0&postcount=30

The BIU (body computer) has a series of diodes inside on the door switch grounding to isolate the two door triggers. This so that the window drop feature when door is opened on one side or another can operate independently and not drop both windows when one door is opened. Now diodes are a tricky things designed for a very specific electrical loads and do heat up and blow if they are loaded with more devices like adding lamps, or using LED with dedicated diodes within it too.

The diodes in the BIU aren’t replaceable and are part of the circuit board so if you blow diodes on the BIU, you’re pretty much going to need to replace it. Upon replacement, you also need to reprogram it as it retains the codes for the ignition key chip transponder as well as ECU handshake, and radio key for remote key fob. (Spelled very expensive trip to the dealer).

So if you’re installing an aftermarket addition, such as alarm triggers, auxiliary power ports, or to the interior lamp or anything on a BIU circuit, it’s best to just run new set of wires separately, and isolated from BIU circuits.