Target vehicle: 2016 Transit Connect

 

There is a metal retaining clip holding the dome light into the headliner, pry at the frontmost (near the windshield) part of the module.

The circuit board can be pried from the housing. There are 4 small PCB break-tabs that clip into retaining slots on the housing.

Once it’s free it looks like this:

 

Preliminary investigation: I’ll check voltages and signals on the 6 pins connecting the dome light module to the vehicle harness.

 

From here I’ll put together a sniffer harness to bring the wires to a more suitable location. Having the scope probe hanging is a bit precarious.

Sniffer Harness v1. I think I transposed a pin so I might have to update it.