Hey all, I have search the forms but haven't been able to see the same problem I am having, I just got a 1996 Ranger XLT for my 16 year old daughter, she wanted a truck so this is one I found after a while looking. It has a few issues the big one I am dealing with is the dash lights and the climate control lights don't work. I have replaced the light switch because I seen that was one of the issues before I h=change out the dimmer switch since they are so expensive I want to see if I need to. It turns the outside bed light on but not the interior light. The interior light does NOT come on when you open the doors either. They only work by the switch. I have checked the fuses all they are all good. Any help I would appreciate. The only other issue that I am worrying about is the speedometer only works some times and when it does it is about 13 miles an hour off. It looks like some one may have recently changed the speed sensor but I got another one since it seems pretty easy to change. I appreciate any suggestions.

 

Welcome to the forum

1996 speedometer is connected directly to the VSS on the tail shaft(assume 2WD), if VSS looks new then pull the whole unit out and inspect the driven gear
Pictures here: https://therangerstation.com/tech_li...edometer.shtml

Works the same as Speedometer cable setup, 3rd and 4th pictures down show the driven gear on the VSS unit, it comes off so you can change gears for larger or smaller tires and correct the speed
On the shaft inside the tail shaft housing is the DRIVE gear, it is a worm gear, it turns the Driven gear, try to see its condition, they can get worn out, although its rare and driven gear should show that.

The VSS has 2 wires, Pink/orange stripe wire should read as a Ground, test with OHM Meter
Grey/black stripe wire runs to the instrument cluster, and Cruise, and computer.
If you have Cruise see if it works, that would mean VSS is working like it should and speedo problem is most likely in the Cluster.

You can use a drill on the VSS unit once it is out, to spin it and test it and the wiring for faults

FYI info:
The VSS is a variable reluctance sensor, it generates its own AC voltage when you spin it, so you can use a volt meter set to AC Volts and hook it up to the VSS then spin it with a drill, should be .5vAC up to about 2.5vAC, so not much, AC voltage is a sine wave, goes above 0volts and below 0volts, so + and - volts, i.e. Alternating current, like in your house
In use one wire on the VSS is a Ground, so no - volts, the + volt side of sine wave is used as a Pulse, the faster the VSS spins the faster the pulses, and thats what is calibrated for speed at speedometer, all Ford speedometers use 8,000PPM(pulses per mile) as true speed calibration, that's why if you change tire diameter the speedo will be off, or rear axle ratio

Speedometer uses an electric motor, and odometer uses a separate electric motor but BOTH use the same signal from the Grey/black stripe wire
So watch odometer when speedometer is not working, if odometer continues to work then the signal is reaching the cluster, so problem is the speedometer itself


Cargo and Dome lights are powered by fuse #27 in cab fuse box, but its power comes from Battery Saver Relay, which is controlled by the GEM(generic electronic module), also known as the BCM(body control module)
GEM runs all the cab electrics, i.e. when you turn on the wipers that switch is hooked to the GEM, it gets the signal from the switch and the GEM turns on the wiper motor, so no direct connection between wiper switch and wiper motor.
The GEM opens Battery Saver Relay after 20-30 minutes when key is off, this would prevent a light from draining the battery if it was left on, when keyless entry is activated, or door is opened GEM "wakes up" and closes Battery Saver relay, giving lights power again

An XLT model Ranger should also have 2 MAP lights along with dome light, they have power full time as long as Battery Saver relay is closed, also from fuse 27, so key on or off doesn't matter.
Map lights and dome light bulbs all share one common Ground, so if that ground was bad then none would work, use meter to test for 12v and ground at map lights

You have voltage at fuse 27 or the Cargo light would not come on, so battery saver relay is working, or at least closed to pass power to dimmer module.

There is an Interior Light Relay, controlled by the GEM, when you open a door GEM is Grounded and closes interior lamp relay turning on Dome light
This relay, along with battery saver relay, is in Relay Box #1, but not sure where that is in 1996 Ranger, my guess would be above gas pedal under the dash


Dimmer module gets dash light power from headlight switch, not fuse 27
A light blue/red stripe wire comes from headlight switch to dimmer module, it should have power when switch is in either park light or head light position
Power out of the dimmer module to cluster lights is on Red/black stripe wire
There are two separate red/black wires at the cluster, each powers 3 bulbs in the cluster, but both come from that one red/black wire at the dimmer module.

To test wires I use a sewing needle to pierce wires to test voltage