The 1989 Jeep Wrangler TJ Starting System consists of battery, starter relay, jeep wrangler TJ starting system diagramstarter within an integral solenoid, ignition switch, clutch pedal position switch for  manual transmission system, park/neutral position switch for automatic transmission, and wire harness/connectors.

The starting system components form two separate circuits. A high-amperage feed circuit that feeds the starter between 150 and 350 amperes, and a low-amperage control circuit that operates on less then 20 amperes. If the vehicle is equipped with an automatic transmission, battery voltage is supplied through the low amperage control circuit to the coil battery terminal of the starter relay when the ignition switch is turned to the Start Position.

Find more about 1989 Jeep Wrangler TJ Starting System overview, description, diagnosis, testing, removal, installation and specification here – 10 pages of PDF filetype. (source: rol.ac.psiweb.com). Find also other and troubleshooting article you might be looking for.