I parted a 71 Dart years ago that had a fried underdash harness. I kept it for redoing the one in my 70 and when I opened up the fried one, I found the brake warning circuit wired wrong.
The downleg wire after the light was only connected to the e-brake switch, but the low fluid circuit was joined at the hot side.
Imagine trying to troubleshoot a hot wire smell that only occurs when the brake fluid is low, much less connecting those two dots!