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Secret is in the ignition switch. Ign Sw should have one or two circuits labeled G1 and G2. One of those is connected to the instrument panel (certain bulbs only) and grounded at the Ign Sw when key is turned to START. This is called bulb check. Circuit is NOT covered within the wiring diagrams. I hate it when they do that.

Looking at the wiring diagrams for MJ and XJ, both have the same Turn Signal switch. Should be the same on both vehicles. Yes NSS is for back up lamps only.

Turn signals lights (L or R) and brake lights (L and R) are basically the same circuit. If you hookup L/R turn signals, you'll get brake lights. Brake lights use the same filament as does the turn signals. Circuit is either a brake circuit or turn signal circuit.

Does this stabilize temperature or does it just stabilize the gauge in the dash? Seems like a simple fix and I hope it works well. Anyone know if the ECT is affected by this? Like I said, hope this works.

My guess is something is using those bulbs as a path to ground. I've seen funny things happen with bulbs when open grounds exist. Sorry, not much help here.

Hi everyone, newbie here. What about a voltage drop test on the ground side of any circuit needing testing. Connect one lead of the VM to the ground side (point of ground) of the circuit being tested and the other lead to the post of the negative side of the battery. Select your lowest voltage scale on the VM. 0vdc is a perfect reading and ground is not your problem. Any reading higher then that indicates issues. Keep in mind this does not cover a vehicle moving (twisting & bending) down the road. You would need to leave the VM hookup for a road test. Now on the lights, jeeps are not the softest in rides, but on-off, off-on, on-off, heats and cools the bulbs many times. This is hard on them. Thermo shock can ruin any light bulb (filament). I like electron flow (- to +).