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Circuit Test HH - Turbo Boost

  1. Use only VOM/DVOM, not STAR tester for this step. Turn key off and wait 10 seconds. Set DVOM on 20-volt scale. Connect DVOM negative test lead to STO at SELF-TEST connector and positive test lead to positive battery terminal. Install a jumper wire between STI and signal return at SELF-TEST connector. Perform KEY ON/ENGINE OFF SELF-TEST  until end of CONTINUOUS SELF-TEST  codes (DVOM reads zero volts). Depress and release throttle while watching DVOM reading. If reading did not change to a high voltage, depress throttle to WOT position and release. If STO voltage does not go to high reading, go to CIRCUIT TEST NN  step 17). Leave test equipment hooked up. If reading changes to high voltage, remain in OUTPUT STATE CHECK  and go to next step.
  2. Turn key on, leave engine off. Set DVOM on 20-volt scale. Connect DVOM positive test lead to VPWR circuit at boost solenoid connector and negative test lead to boost output on boost solenoid connector. Depress and release throttle several times while reading DVOM. If boost solenoid does not cycle, remove jumper wire and go to step 4). If boost solenoid cycles, go to next step.
  3. Remain in OUTPUT STATE CHECK  . Disconnect plain Black (not Black/Yellow) solenoid vacuum hose from turbocharger end. Attach vacuum pump to hose. Depress throttle once to cycle solenoid to closed position. Apply vacuum to solenoid, then depress throttle to cycle solenoid to open position and release vacuum. If solenoid does not hold and release vacuum properly, replace solenoid and repeat QUICK TEST  . If solenoid works correctly, EEC-IV is okay. Check turbocharger boost system.
  4. Turn key off and wait 10 seconds. Disconnect boost solenoid connector. With DVOM on 200-ohm scale, measure resistance of boost solenoid. If reading is less than 65 ohms or more than 110 ohms, replace boost solenoid and repeat QUICK TEST  . If reading is between 65 and 110 ohms, connect boost solenoid and go to next step.
  5. Turn key on, leaving engine off. Set DVOM on 20-volt scale. Measure voltage between VPWR circuit at solenoid connector and battery ground. If reading is less than 10.5 volts, repair open in harness and repeat QUICK TEST  . If reading is 10.5 volts or more, go to next step.
  6. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 32 and boost circuit at harness connector. If reading is 5 ohms or more, repair open and repeat QUICK TEST  . If reading is less than 5 ohms, go to next step.
  7. Turn key off and wait 10 seconds. Leave breakout box installed and ECA disconnected. Disconnect boost solenoid and set DVOM on 200,000-ohm scale. Measure resistance between test pin No. 32 and test pins No. 40, 46, and 60. If any reading is less than 10,000 ohms, repair short to ground and repeat QUICK TEST  . If all readings are 10,000 ohms or more, go to next step.
  8. Turn key off and wait 10 seconds. Leave breakout box installed, ECA disconnected, and DVOM on 200,000-ohm scale. With boost solenoid disconnected, measure resistance between test pin No. 32 and test pins No. 37 and 57. If any reading is less than 10,000 ohms, repair short to power and repeat QUICK TEST  . If symptom is still present, replace ECA. If all readings are 10,000 ohms or more, replace ECA and repeat QUICK TEST  .
Fig 1: Turbo Boost Circuit
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