Hello! I was wondering if the computer is responsible for running anything but the engine. For example, does it run the headlights, turn signals, or dash lighting? Thanks!

 

Take a look at the list of PCM inputs & outputs, specificly for your Year Make Model Engin Trans....
that will tell you exactly what the PCM controls directly,
& give you an idea of what input variables are used to drive the outputs via the PCM firmware logic.

 

No, Ranger computer never controlled any thing but the drive train

1986 thru 1994 the PCM(engine computer) only operates fuel system and some automatic transmission controls
Spark was controlled by a smaller "computer" module

1995 and up PCM controlled fuel and spark both, and full control of automatic transmission

2WD or 4x4 was never part of PCM control, or any of the cab electrics or lights, manual transmissions didn't need PCM(computer control)

1995 thru 2003 Rangers had a GEM module, behind the radio, it controlled some cab electrics, i.e. dome light and wipers
2004 thru 2011 Rangers got the SJB to replace the GEM, passenger side kick panel, cab fuse box is part of the SJB

Headlights, parking lights, dash lights, brake lights and turn signals tends to be separate systems for better reliability, but each year Ranger WILL HAVE its own sub-wiring for these systems

So you need to ask specific questions, and include the year of Ranger at least, engine size, transmission type, 2WD or 4x4 can also be included