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Power Circuits (2.5L)

  1. Using a voltmeter, check for battery voltage between ECU terminal No. 4 and ground. See Fig 1 and Fig 2 . If battery voltage is not present, check for an open in Red wire between ECU and battery.
    Fig 1: 2.5L ECU Connector Diagram (Cherokee & Comanche)
    G90E15879Courtesy of CHRYSLER MOTORS.
  2. Turn ignition switch to the ON position. Using a voltmeter, check for battery voltage between ECU terminal No. 3 and ground. See Fig 1 and Fig 2 . If battery voltage is not present, check for an open in Black wire between ignition switch and terminal No. 3 of ECU, or check for a defective ignition switch.
    Fig 2: 2.5L ECU Connector Diagram (Wrangler)
    G90H15880Courtesy of CHRYSLER MOTORS.
  3. Connect a voltmeter between ground and ECU terminal No. 29. See Fig 1 and Fig 2 . Turn ignition switch to the START position. Battery voltage should be present between control unit terminal No. 29 and ground ONLY when ignition switch is in the START position. If voltage is not present, check for an open in Green wire between ECU terminal No. 29 and start relay, or check for a defective ignition switch.