Ya, the top lamp is the Tail / Stop lamp. Check for battery volts at the socket with parking lamps on. It's not uncommon for the socket to go bad.

 

Do yourself a favor. Head over to eBay and buy a box of replacement sockets (6) and a new light board for each side and be done with it.
Start with new everything or else you are going to be playing around with this forever. There are only 3 predominant parts. Bulbs, sockets and the boards. Start with new of each and you will have more time for the hundreds of other different issues that are guaranteed to arise for as long as you own your jeep:.

 

I fought this same issue for a while before finally just buying tail light assemblies that wire in. I never cared for the huge red/orange assemblies anyway.

 

Incandescent lamps create a lot of heat that takes its toll over time on these vehicles. I’ve owned more vehicles than I can recall at this point and I never encountered socket or light board issues on any , but these WJs. Poor design, flimsy construction, cheap materials, I have no idea why.

 

Ctrl C, Ctrl V for reference:

"Rear taillight sockets fail. Dorman sells a cheap replacement. If you replace them, be sure and check the contact points in the taillight assembly – they are a failure point as well, and need a tweak upward with a pick or small screw driver to make good contact with the sockets. I replaced my taillight assys and STILL needed to tweak those contact pads on the brand new replacement. Note if they have been arching long enough and you’re pulling your hair out trying to get them to light, you probably blew the #23 fuse under the dash."


Dorman sockets

Cheap tail light assy set

LED Hi-mount brake light assy

 

So, I got new sockets, bulbs and a new Dorman circuit board (part #923-036). Top lights STILL won’t work. All other lights work fine. Makes me think there is something else internal going on here. Is there maybe a fuse for JUST these 2 top tail lights.

 

There is not one fuse for just the top lights.

 

Time to get a meter and see if it has power at the wires to the bulb.

 

Well, still was unable to get these top tail lights to work. Since I don’t really drive it much (since it’s essentially a 3rd “spare” vehicle at this point) & i plan to probably sell it soon, I just decided to make it a winter/fall daytime driving vehicle;

winter/fall cause no AC, but heat works fine.
Daytime driving cause the break lights work, but no tail lights for night time driving.

I then realized that when I do use a trailer with it, the trailer lights work great. Therefore wondering if there is maybe a cheap or temporary solution that would allow me to hook some sort of light kit up to the hitch’s light plug.

Not sure there is and probably would have to be home made, but worth a shot asking here

any suggestions on a quick contraption?

 

Are you saying the hi-mount light above the flipper glass is lighting only when you brake? That is normal operation - it does not light with the headlights, only brakes...

 

So...results of using a meter to test the connectors?

 

Are you saying the hi-mount light above the flipper glass is lighting only when you brake? That is normal operation - it does not light with the headlights, only brakes...

I guess its then not the "hi-mount" light like you mention. Basically, the break lights are working fine. NOTHING lights up on the rear when I turn on the main lights in a normal fashion. The front headlights work fine. I get no normal tail lights in the rear when not tapping on the break

So...results of using a meter to test the connectors?

No didn't test with a meter. I don't have a meter to test it and if I got one, not really familiar with how to use one and don't really want to mess with all that anyway. Was then thinking of another possible easy option. Hence the reason I mentioned maybe I could come up with something that would simply attach to the trailer hitch light socket. I know, not ideal and it would really only be used if needed (since I try to drive it mostly during the day anyway)

Probably not and just wondering

 

I think Harbor Freight has a trailer towing light kit. I think it uses magnets and a long run of wire to stick external lights to a towed vehicle. Amazon has similar kits.
Not sure if it has the socket configuration for what you're trying to do but it could probably be made to work an adapter provided your WJ has the tow package already.
It's $25 or so and you'll need the trailer connector adapter that changes the round 7-pin plug to a 4-pin flat plug. Those are found at any parts store for about $5.

HF also has a voltmeter for about $5 and a u-tube video on how to use a meter is free.

 

Cherokee Sport isn't even close to a Grand Cherokee.
I know this sounds nuts, but just give the bulbs a little wiggle or turn. I go round and round with mine, usually just turning the bulb oh so slightly gets it working again. Mine seems random on which goes, brake or taillight.