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Test H - Idle Tracking Switch (Its)

  1. If code 58 is present, go to next step. If code 68 is present, go to step  5 .
  2. Code 58. Turn ignition off and wait 10 seconds. Press on ISC motor shaft to simulate throttle contact. With pressure on ISC motor shaft, perform KEY ON-ENGINE OFF (KOEO) SELF-TEST  and note codes. If code 68 is present, go to TEST K  , step 4). If code 68 is not present, go to next step. Ignore all other codes at this time.
  3. Turn ignition off and wait 10 seconds. Disconnect harness at ISC motor. Perform KEY ON-ENGINE OFF (KOEO) SELF-TEST  . If code 68 is present, replace ISC DC motor and repeat QUICK TEST  . If code 68 is not present, go to next step.
  4. Turn ignition off and wait 10 seconds. Disconnect 60-pin connector at ECA and inspect. Connect breakout box and leave ECA disconnected. With harness disconnected at ISC, place DVOM on 200,000 ohm scale. Measure resistance from box pin 28 to pins 40, 46 and 60 in turn. If any resistance less than 10,000 ohms, service short to ground and repeat QUICK TEST  . If all are 10,000 ohms or more, replace ECA and repeat QUICK TEST  .
  5. Code 68. Turn ignition off and wait 10 seconds. Move throttle away from ISC DC motor shaft. Perform KEY ON-ENGINE OFF (KOEO) SELF-TEST  . If code 68 present, go to next step. If no code 68, go to TEST K  , step 4). Ignore all other codes at this time.
  6. Turn ignition off and wait 10 seconds. Disconnect harness at ISC motor. Connect jumper wire between pins 3 and 4 of ISC harness connector (signal return and idle tracking switch circuits). DO NOT  short any other pins. Perform KEY ON-ENGINE OFF (KOEO) SELF-TEST  . If code 68 is present, go to next step. If no code 68, replace ISC DC motor and repeat QUICK TEST  .
  7. Turn ignition off and wait 10 seconds. Disconnect 60-pin connector at ECA and inspect. Connect breakout box and leave ECA disconnected. With DVOM on 200 ohm scale, measure continuity from box pin 46 to pin 28. If either is 5 ohms or more, service faulty circuit and repeat QUICK TEST  . If both less than 5 ohms, replace ECA and repeat QUICK TEST  .
Fig 1: Idle Tracking Switch Circuit
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