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Code 68

  1. 9)  Checking ISC DC Motor Movement. Observe DC motor and rerun SELF-TEST. If motor shaft moves during SELF-TEST, go to next step. If motor does not move, go to step 12).
  2. 10)  Checking ITS At ISC DC Motor. With key off, disconnect harness connector from ISC DC motor. Set DVOM on 200-ohm scale. Connect DVOM to ISC DC motor connector (as shown). Move throttle lever so it is not contacting motor shaft. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, replace ISC DC motor. Rerun SELF-TEST.
    Fig 1: ISC DC Motor Connector
    G72398
  3. 11)  Checking ITS and Ground Continuity. Turn ignition off and disconnect harness from ISC DC motor. Disconnect ISC-E processor 24-pin connector. Set DVOM on 200-ohm scale. Measure resistance 24-pin connector, pin No. 7 and ITS circuit at DC motor harness connector. Measure resistance between ground circuit at ISC DC motor harness connector and negative (-) battery terminal. If both resistances are less than 5 ohms, replace processor, reconnect system and retest. If resistance is greater than 5 ohms, repair open circuit, reconnect system and retest.
    Fig 2: ISC DC Motor, Vehicle Harness Connector
    G72399
  4. 12)  Checking ISC DC Motor Operation. Turn ignition off and disconnect harness connector from ISC DC motor. Jumper battery positive (+) terminal to ISC positive (+) circuit. Jumper battery negative (-) terminal to ISC negative (-) circuit. Reverse polarity of jumper wires and check shaft movement. If motor shaft moves in both directions, go to next step. If shaft does not move in both directions, replace ISC DC motor and retest.
    CAUTION: When using battery voltage to test ISC DC motor, ensure ITS terminals are protected as per the illustration.
    Fig 3: ISC DC Motor Connector
    G72400
  5. 13)  Checking ISC Circuit Continuity. With key off, disconnect harness from ISC DC motor. Disconnect processor 24-pin connector. Set DVOM on 200-ohm scale. Measure resistance between pin No. 11, ISC negative (-) circuit and ISC DC motor harness connector. Measure resistance between processor 24-pin connector, pin No. 22 and ISC positive (+) circuit at ISC DC motor harness connector. If both resistances are less than 5 ohms, go to next step. If resistances are not less than 5 ohms, repair open circuit, reconnect system and retest.
  6. 14)  Checking ISC Circuits for Shorts to Power Disconnect ISC DC motor harness connector and processor 24-pin connector. Set DVOM on 20-volt scale. Turn ignition on, with engine off. Measure voltage between processor 24-pin connector pin No. 11 and chassis ground. Measure voltage between processor 24-pin connector pin No. 22 and chassis ground. If both voltages are less than one volt, go to next step. If voltages are not less than one volt, repair short circuit and retest. If ISC DC motor still does not move, replace ISC-E processor.
  7. 15)  Checking ISC Circuits for Shorts to Ground. With ignition off, disconnect ISC DC motor and processor. Set DVOM 200,000-ohm scale. Measure resistance between processor 24-pin connector pin No. 11 and chassis ground. Measure resistance between processor 24-pin connector pin No. 22 and chassis ground. If both resistances are greater than 10,000 ohms, replace ISC-E processor. If resistances are less than 10,000 ohms, repair short circuit and retest. If ISC DC motor still does not move, replace processor.
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