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Test V - Air Management System

To prevent replacement of good components, be aware that the following non-EEC related areas may be at fault: thermactor air system drive belt, air pump or valve.

  1. Codes 44 (94), 45 (95) & 46 (96) Displayed. Ensure correct vacuum line routing to TAB/TAD solenoids and by-pass diverter valve. Use vehicle emissions label as a guide. Check for kinked or blocked vacuum lines. Check for kinked or blocked air hoses. Check for disconnected vacuum lines. If problems are detected, correct hose routing, repair faults and repeat QUICK TEST . If hoses are good and code 44 (94) is displayed, go to step 4). If code 46 (96) is displayed, go to step 3). If code 45 (95) is displayed, go to next step.
  2. Code 45 (95) Displayed. This test applies to TAD equipped models only. Disconnect and plug vacuum line at diverter valve. Turn key off and wait 10 seconds. Repeat ENGINE RUNNING SELF-TEST and record codes. If code 45 (95) is displayed, EEC-IV system is okay. Check diverter valve and/or check valve for problem. If code 45 (95) is not displayed, go to step 4).
  3. Code 46 (96) Displayed. This test applies to TAB equipped models only. Disconnect and plug vacuum line at by-pass valve. Turn key off and wait 10 seconds. Repeat ENGINE RUNNING SELF-TEST and record codes. If code 46 (96) is displayed, EEC-IV system is okay. Check by-pass valve for problem. If code 46 (96) is not displayed, go to next step.
  4. Use only VOM/DVOM, not STAR tester, for this step. Turn key off and wait 10 seconds. With DVOM on 20-volt scale, connect DVOM negative test lead to STO at SELF-TEST connector and positive test lead to battery positive terminal. Using a jumper wire, connect STI circuit to 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. DVOM should change to a high voltage reading. If reading did not change, depress throttle to WOT and release. If STO voltage does not go high, go to TEST HH - NO CODES/CODES NOT LISTED , step 15). Leave test equipment hooked up. If reading changed, remain in OUTPUT STATE CHECK and go to next step.
  5. Set DVOM on 20-volt scale. Connect DVOM positive test lead to VPWR circuit and negative test lead to TAB circuit at TAB solenoid. While observing DVOM, depress and release throttle several times to cycle output on and off. Repeat for TAD solenoid. Connect positive test lead to VPWR circuit and negative test lead to TAD circuit at TAD solenoid. Cycle output on and off. If either solenoid does not cycle on and off, remove jumper and go to step 8). If both solenoids cycle on and off, go to next step.
  6. Connect vacuum pump to TAB solenoid vacuum supply port. Connect vacuum gauge to output port. Maintain vacuum at source while depressing and releasing throttle to cycle output on and off. Observe vacuum gauge. Repeat for TAD solenoid. If either vacuum output does not cycle on and off, replace solenoid assembly and repeat QUICK TEST . If both vacuum outputs cycle on and off, go to next step.
  7. With vacuum lines disconnected at TAB/TAD solenoid assembly, start engine and check for vacuum. If vacuum is present, EEC-IV system is okay. Check thermactor valve and air pump for problem. If no vacuum is present, repair blockage and/or leaks as required and repeat QUICK TEST .
  8. Turn key off and wait 10 seconds. Set DVOM on 200-ohm scale. Disconnect TAB and TAD solenoid connectors. Measure resistance of both solenoids. If either reading is less than 50 ohms or more than 100 ohms, replace TAB/TAD solenoid assembly and repeat QUICK TEST . If both readings are between 50 and 100 ohms, connect TAB and TAD solenoids. Go to next step.
  9. Turn key on, leaving engine off. Set DVOM on 20-volt scale. Measure voltage between TAB solenoid VPWR circuit and battery ground. Repeat for TAD solenoid. If either voltage reading is less than 10.5 volts, repair open circuit and repeat QUICK TEST . If both readings are higher than 10.5 volts, go to next step.
  10. 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. With DVOM on 200-ohm scale, measure resistance between test pin 51 and TAB circuit at harness connector. Measure resistance between test pin 11 and TAD circuit at harness connector. If either reading is 5 ohms or higher, repair harness open circuit and repeat QUICK TEST . If both readings are less than 5 ohms, go to next step.
  11. Turn key off and wait 10 seconds. Set DVOM on 200,000-ohm scale. Leave breakout box installed and ECA disconnected. Disconnect TAB and TAD solenoid, and measure resistance between test pins 51 and/or 11 and test pins 37 and 57. If any reading is less than 10,000 ohms, repair short to power and repeat QUICK TEST . If any reading is 10,000 ohms or more, go to next step.
  12. Turn key off and wait 10 seconds. Set DVOM on 200,000-ohm scale. Leave breakout box installed and ECA disconnected. Disconnect TAB and TAD solenoid, and measure resistance between test pins 51 and/or 11 and test pins 40, 46 and 60. If any reading is less than 10,000 ohms, repair circuit short to ground. Remove breakout box, connect harness to ECA and repeat QUICK TEST . If code is repeated, replace ECA. If any reading is 10,000 ohms or more, replace ECA. Remove breakout box, connect harness to ECA and repeat QUICK TEST .
Fig 1: Air Management Circuits
G11095
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