dave1123

IDK about Jeep's circuit board because I've never had one apart, but this may help. On my GM trucks, the circuit board was two sheets of clear plastic with the copper strips embedded in between. It should be easy to trace the copper back to the connector strip. On my truck, I had several dash illuminating lights out so I replaced all the bulbs. I still had lights out so I took out the cluster. I found the contacts at the bulb sockets had been overheated enough to soften the plastic and not make contact. What I did was stiffen the plastic with Superglue, polish the contacts, and install the bulbs while the cluster was in my hands. Worked for me. It seems the PO had replaced the bulbs with side marker light bulbs, not dash light bulbs. The difference in wattage caused the overheating.

On YOUR dash, there may be a spot where two circuits cross causing the CEL to light, maybe the supply circuit for one of the guages.

Creature85

I'm not sure what color wire it would be as I've never taken the cluster apart, but there should be traces on the board that go from the bulb terminals to the harness plug terminals. That is if those components aren't surface mounted and the traces aren't hidden within multiple layers of the circuit board.