\what is this

[morbert]

1989 Ranger XLT extended cab. Behind the driver jump seat in the cubby hole there is a black box with 3 wire plugs. On the top of this is a button, when pushed a small LED light comes on for about 30 seconds. What is this?

 

[Snoranger]

4x4 shift module for the electric shift T-case.

 

[morbert]

So the LED light is for testing the system operation?

 

[4.0B2]

i have one in my dash.. and always wondered why it had a light on it... lol

 

[4x4junkie]

So the LED light is for testing the system operation?

Yep, it's a self-test button & light for just the controller module itself.
You should hear relays click and the light should blink 4 times in a row if it's working properly (you MUST disconnect the two connectors on the end to conduct the self-test though, leaving just the pigtail lead connected, otherwise you get a solid red light which would otherwise indicate a Fail).