1999 jeep wrangler dash

The interior lights turn on via a ground I believe which implies your Jeep is missing the proper ground.

There is a mesh strap from the head to the firewall on the 4.0's that supplies body ground.

The older Jeeps had a back of the dash panel ground for the headlight switch.

The 99's also have a recall on the dash grounds. This might tie in, don't know.

Here is the recall:

Recall 99V117000: Instrument Panel Ground Screws Loose

The left side and right side instrument panel wiring ground attachment screws could loosen over time. If the left side screw loosens, the instrument panel gauges may not function when the headlamps are turned on. If the right side screw loosens, the defroster blower motor may not function.

Dealers will remove the ground screws, drill a new pilot hole adjacent to the original hole, and the screws will be reinstalled in the new holes.

Owner notification began May 31, 1999. Owners who take their vehicles to an authorized dealer on an agreed upon service date and do not receive the free remedy within a reasonable time should contact Chrysler at 1-800-992-1997. Also contact the National Highway Traffic Safety Administration's Auto Safety Hotline at 1-888-DASH-2-DOT (1-888-327-4236).

Mike