How to tell if 4wd is working - 1987 Jeep Wrangler

Go down to the dealership and their factory scan tool will tell you the exact reason for this. It will be a sensor somewhere.

usa? not diesel?
why are you in 4wd? snow, ice, off road, do tell.
not sure what lamps are dead, no photo by you.
are you talking parking lamps dead in dash? called illumination
or the mode lamps. ????
where on the dash, the main cluster? where? TRY TO BE EXACT.
do you mean shift console lamps, ????? those are on the dimmer feed.
the best answer is get car serviced
or scan it, see if there are errors. to the 4wd system etc.

we cant do grinds here, we deaf and blind and....
find a shop , that can find LOCATIONS. of noise
only That works, ever.
grinding in all modes of use, parked, neutral. driving, hills, gears.
??????????
do you have any warning lamps glowing ,driving?
the lamps if the 4wd lamps are dead.
tell me you are not using 4Low mode on pavement, first.
most times fuse are first, 2007 this changes but 2005
there are 2 fuse boxes, cab and eng bay.

ON PAGE 166 in the oper guide
lamp 6 dead, 4low?
lamp 19 FULL TIME , dead or stuck on??????
or the switch bank dead?
command trac or select trac 4wd.? NV241 or NV242?
2 options day 1.

here is my guess,
you are using 4wd incorrectly
do tell what tires are sitting on.
the me it car is command or select trac opted
and all lever selections you tried.
EACH 4wd mode has rules.
rule one stay out of 4-low. unless off road

the opr guide is here if lost.
see the word secret , here.

http://jeepdied.com/books.html

command trac, 4w is not for driving on ice free pavemenet
Comman trac is part time 4wd, (the word part meas, ice or dirt)
select trac, is full time, (never in 2w low) 4H works on pavement even dry. page 240 in your op guide.
The rules on the 2 boxes are totally different.

Most likely cause is the encoder motor on the transfer case. This is the motor that activates the transfer case. Usually sets a code so you may want to have it scanned.

Did you reverse more than 10 metres? Sounds like the hubs are locked into 4wd.this will work if you have auto hubs.but sometimes you have to turn the hub manually if they don't disengage.if you have gone some time or distance in 4wd

check under neath to see that the unit is actually moving into 4wd. It needs to do this to move a micro swith to tell you that somthing has happened. what you appear to have is one light telling you that the power is available but the second light saying that nothing has moved as required a fact born out buy not having 4wd

easiest way to tell if it is 2 wheel or 4 wheel is look under the car. From the front of the vehicle just off center (could be left or right) there will be a differential. (much like what you see under the rear of a pickup truck. If you see this it's a 4wd or awd. The difference between awd and 4wd is- 4wd is either front or rear wheel drive with the ability to (now days) push a button and "lock in" the other axel. Awd is at all times, all 4 wheels are working together to move the vehicle.

the switch is probably from a newer modle truck, although they work the indicator lights don't always work, and check the 4x4 fuse in the fuse panel on the left side of the dash by the drivers door

can you hear the shifter motor trying 2 shift? if not its the shifter motor open the door and try 2 listen when your trying 2 shift it

There is a switch on top of the t-case that turns the light on when in 4wd. If the switch is bad, the jeep can be in 4wd and not show the light. Put the car in 4wd and make sharp circle turn, you can tell if the jeep is in 4wd.

Don't know if this will help with your exact problem, but I can share with you how I have "fixed" this.

If the 4WD indicator is flashing, then it means the 4WD select switch is working but the 4wd "clutch" hasn't released. Backing the vehicle up slowly, or sometimes just switching into reverse with the 4WD switch in the 2WD position is usually enough to release the 4WD and the 4WD indicator should go off. It after all this, the indicator still does not go off, it could be some issue with the electric 4WD clutch not releasing.
You should be able to tell if the 4WD drive is still engaged by driving slowly in a circle. On drive pavement, the front wheels will "hop" around. Don't do this too fast or too often on drive pavement, since the part time 4WD was not meant for this. The front wheels have to be able to slip in relation to each other, when in 4WD.

Hope this helps and wish you well in your troubleshooting.