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Test KA - EGR On/Off Control

NOTE: Perform this test only when directed here by a driveability symptom.
NOTE: This test is intended to diagnose only the following components and circuits:
  • Harness circuits (EGR and VPWR)
  • EGR solenoid
  • Presence of manifold vacuum
  • ECA
    NOTE: To prevent replacement of good components, be aware that the following non-EEC related areas may be at fault:
  • Air or vacuum leaks
  • EGR flow restrictions
  • EGR valve
Fig 1: EGR On/Off Circuit
G90H13133
  1. Enter Output State Check  Possible causes for this fault are:
    • Faulty EGR On/Off control solenoid
    • Faulty EGR solenoid
    • Faulty EGR vent solenoid
    • Faulty EVP sensor
    • Faulty wiring harness
    • Faulty ECA
    • Manifold vacuum line blocked or leaking

    Use only VOM/DVOM, not diagnostic tester, for this step. Turn key off and wait 10 seconds. Disconnect electrical connector on speed control servo (if equipped). Set DVOM on 20-volt scale. Connect negative DVOM lead to STO at Self-Test connector and positive lead to positive battery terminal. Jumper STI to SIG RTN at Self-Test connector. Rerun KOEO SELF-TEST  until end of Continuous Memory Codes display (DVOM will read less than one volt). Depress and release throttle and observe DVOM reading. If DVOM reading changes to a higher voltage, stay in OUTPUT STATE CHECK and go to next step. If DVOM did not show high voltage, depress throttle to WOT and release. If STO voltage does not increase, go to TEST QC, step 1. Leave test equipment hooked up.

  2. Check EGR Solenoid Electrical Operation  Disconnect EGR solenoid. Set DVOM on 20-volt scale. Connect DVOM positive lead to VPWR circuit at EGR solenoid and negative lead to EGR output circuit. While observing DVOM, depress and release throttle several times to cycle output on and off. If output does not cycle on and off, remove STI jumper wire and go to step 5. If output cycles on and off, go to next step.
  3. Check EGR Solenoid For Vacuum Cycling  Reconnect EGR solenoid. Connect vacuum pump to solenoid vacuum supply port and vacuum gauge to output port of solenoid. Apply minimum vacuum of 6 in. Hg. Depress and release throttle several times to cycle EGR solenoid output while maintaining vacuum at supply port. Note gauge reading. If vacuum output does not cycle, replace EGR solenoid and repeat QUICK TEST PROCEDURES . If vacuum output cycles, go to next step.
  4. Check Manifold Vacuum Lines For Blockage or Leaks  With vacuum lines disconnected at EGR solenoid, start engine. If vacuum is present, EEC-IV system is not cause of problem. Check EGR system for mechanical faults. If vacuum is not present, correct vacuum source blockage or leak and repeat QUICK TEST PROCEDURES .
  5. Measure EGR Solenoid Resistance  Turn key off and wait 10 seconds. Disconnect EGR solenoid. Set DVOM on 200-ohm scale. Measure resistance between EGR circuit and VPWR circuit at the EGR solenoid. If reading is less than 65 ohms or more than 110 ohms, replace EGR solenoid and repeat QUICK TEST PROCEDURES . If reading is between 65 and 110 ohms, go to next step.
  6. Check VPWR Circuit Voltage  With KOEO and EGR solenoid disconnected, set DVOM on 20-volt scale. Measure voltage between VPWR circuit at EGR solenoid vehicle harness connector and battery ground. If reading is less than 10.5 volts, repair open in harness, reconnect EGR solenoid and repeat QUICK TEST PROCEDURES . If reading is 10.5 volts or more, go to next step.
  7. Check Continuity of EGR Circuit  Turn key off and wait 10 seconds. Disconnect EGR solenoid. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 35 at the breakout box and EGR circuit at EGR solenoid vehicle harness connector. If reading is 5 ohms or more, repair open circuit and repeat QUICK TEST PROCEDURES . If reading is less than 5 ohms, go to next step.
  8. Check EGR Circuit For Short to Ground  Turn key off and wait 10 seconds. Leave breakout box installed and ECA disconnected. Disconnect EGR solenoid. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 35 and test pins No. 40, 46, and 60. If any reading is less than 10 k/ohms, repair short to ground and reconnect all components. Repeat QUICK TEST PROCEDURES . If all readings are 10 k/ohms or more, go to next step.
  9. Check EGR Circuit For Short to Power  Turn key off and wait 10 seconds. Leave breakout box installed. Disconnect ECA and EGR solenoid. With DVOM on 200-k/ohm scale, measure resistance between test pin No. 35 and test pins No. 37 and 57. If any reading is less than 10 k/ohms, repair short to power and repeat QUICK TEST PROCEDURES . If fault is still present, replace ECA. If all readings are 10 k/ohms or more, replace ECA and repeat QUICK TEST.
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