That is the emissions timer. It's only job is to turn on the emissions maintenance light at around 75,000 miles. At which point you are supposed to replace the O2 sensor. It's non resettable and not user serviceable. Once it triggers it's done.
A forum community dedicated to Jeep Wrangler owners and enthusiasts. Come join the discussion about reviews, performance, trail riding, gear, suspension, tires, classifieds, troubleshooting, maintenance, for all JL, JT, JK, TJ, YJ, and CJ models!