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Test BB - 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. Check for correct vacuum hose routing to TAB/TAD solenoids and by-pass diverter valve. Use vehicle emissions label as a guide. Check for kinked or blocked vacuum hoses. Check for kinked or blocked air hoses. Check for disconnected vacuum hoses. 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 step checks TAD solenoid only. Disconnect and plug vacuum hose at diverter valve. Turn key off and wait 10 seconds. Repeat KEY ON/ENGINE RUNNING (KOER) SELF-TEST and record codes. If code 45 (95) is displayed, EEC 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 step checks TAB solenoid only. Disconnect and plug vacuum hose at by-pass valve. Turn key off and wait 10 seconds. Repeat KOER SELF-TEST and record codes. If code 46 (96) is displayed, EEC system is okay. Check by-pass valve for problem. If code 46 (96) is not displayed, go to next step.
  4. Use only DVOM, not diagnostic tester, for this step. Turn key off and wait 10 seconds. With DVOM on 20-volt scale, connect DVOM negative test lead to STO circuit at SELF-TEST connector and positive test lead to battery positive terminal. Using jumper wire, connect STI circuit to signal return at SELF-TEST connector. Perform KEY ON/ENGINE OFF (KOEO) 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 changed, remain in OUTPUT STATE CHECK and go to next step. If reading did not change, depress throttle to WOT and release. If STO voltage does not go high, go to TEST PP - NO CODES/CODES NOT LISTED  , step 14). Leave test equipment hooked up.
  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 output does not cycle on and off, replace TAB/TAD solenoid assembly and repeat QUICK TEST  . If both outputs cycle on and off, go to next step.
  7. With vacuum hoses disconnected at TAB/TAD solenoid assembly, start engine and check for vacuum. If vacuum is present, EEC system is okay. Check thermactor valve and air pump for problems. If no vacuum is present, repair blockage 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 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 harness circuit open 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 connector for damaged pins, corrosion, or loose wires. Install breakout box, leaving ECA disconnected. With DVOM on 200-ohm scale, measure resistance between test pin No. 51 and TAB circuit at harness connector. Measure resistance between test pin No. 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 solenoids, and measure resistance between test pin No. 51 and test pins No. 40, 46 and 60. Also measure resistance between test pin No. 11 and test pins No. 40, 46 and 60. If any reading is less than 10,000 ohms, repair short to ground. Remove breakout box, connect harness to ECA, and repeat QUICK TEST  . If all readings are 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 solenoids, and measure resistance between test pin No. 51 and test pins No. 37 and 57 and between test pin No. 11 and test pins No. 37 and 57. If any reading is less than 10,000 ohms, repair short to power. Remove breakout box, connect harness to ECA and repeat QUICK TEST  . If code is repeated, replace ECA. If all readings are 10,000 ohms or more, replace ECA and repeat QUICK TEST  .
Fig 1: Air Management Circuits
G6050
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