I just got a 2003 Crown Vic Police Interceptor with only 59k on it and I realized the damn brake lights don't work. The third / upper works, and either of the rear lights works fine with the blinkers and hazard. Only the rear upper mounted brake light works with the brake pedal. All other lights work just fine

What I have done thus far -
Checked all fuses (the only location that should have had a fuse that did not was the #2 or "Audio" but that's weird because the stereo works just fine.. anyway it was replaced
Replaced the multifunction switch (Went from an OEM to a NAPA and had to change the pins into a new connector.. No change)
Inspected wiring and condition of harnesses in general area around steering column and under dash.

As I understand it, the brake light switch has to work because the 3rd light works fine as soon as the brake pedal is pressed. The fuse and ground to the brake light system is fine because either of the tail lights only have 3 wires and the blinkers and running lights switch works both filaments just fine. The only other suspicious culprit would be a severed dark blue wire from the lighting control module. I can pinch the wires together while I press the brake pedal and that does not seem to do anything either. I did not fix this, I just tried to temporarily connect the circuit while pressing down on the brake pedal and verified with a friend that it did not solve the issue.

I'm having a hard time finding a decent wiring diagram, all of the links I've come across are expired or the diagram is spread over 5 pages.

Does anyone have any insight on this or have access to a good wiring diagram? I feel like it has to be a wiring problem between the pedal to the multifunction switch or maybe the lighting control module. I also have not found a diagram that shows the circuit that includes the 3 harnesses that plug into the MFS or one that has included the Lighting Control MO

Thank you for bearing through this.

 

Since you just got the vehicle, and it has had emergency lighting systems removed before sale, chances are pretty good someone left a wire disconnected.

You may need to start from the plug in the trunk area that distributes power to the various lights in the rear and see if you can spot a wire that was interrupted and very likely not reconnected.