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Test I - EGR Valve Position (EVP) Sensor

  1. Code 31. Turn ignition off and wait 10 seconds. Disconnect and plug EGR vacuum line at EGR valve. Perform KEY ON-ENGINE RUNNING (KOER) SELF-TEST  . If code 31, go to next step. If no code 31, but codes 32 and/or 34 present, go to step  9 .
  2. Turn ignition off and wait 10 seconds. EGR vacuum line disconnected and plugged at EGR valve. Disconnect harness connector at EGR valve position (EVP) sensor and inspect terminals for damage. Repair as required. With DVOM on 200,000 ohm scale, measure resistance from EVP signal circuit to voltage reference circuit at EVP sensor. Then measure resistance from signal return circuit to voltage reference circuit at sensor. If both readings are 100-5500 ohms, go to next step. If either reading is less than 100 ohms or more than 5500 ohms, replace sensor and repeat QUICK TEST  .
  3. Ignition off, EGR vacuum line disconnected and plugged and harness disconnected at EVP sensor. Connect vacuum pump to EGR valve. With DVOM on 200,000 ohm scale, measure resistance from EVP signal circuit to voltage reference circuit at EVP sensor while gradually increasing vacuum to 10 in. Hg. If reading gradually decreases from no more than 5500 ohms to no less than 100 ohms as vacuum is increased, go to next step. If reading is less than 100 ohms or more than 5500 ohms as vacuum is increased, replace sensor and repeat QUICK TEST  . If reading does not decrease or sensor does not hold vacuum, go to step  12 .
  4. Turn ignition on (engine off). EGR vacuum line disconnected and plugged and harness disconnected at EVP sensor. With DVOM on 20 volt scale, measure voltage from voltage reference circuit to signal return circuit at sensor harness. If reading is 4-6 volts, go to next step. If reading is less than 4 volts, go to step  7 . If reading is greater than 6 volts, go to TEST C  .
  5. Ignition on (engine off). Reconnect EGR vacuum line at EGR valve and leave harness disconnected. With DVOM on 20 volt scale, measure voltage from voltage reference circuit to EVP signal circuit at sensor harness. If reading is 4-6 volts, go to next step. If reading is less than 4 volts, go to step  7 .
  6. Turn ignition off and wait 10 seconds. Harness disconnected at EVP sensor. Disconnect 60-pin connector at ECA and inspect for damaged terminals. Repair as required. Reconnect 60-pin connector before checking resistance of the EVP Sensor. With DVOM on 200,000 ohm scale, measure resistance from EVP signal circuit to signal return circuit at sensor harness and from EVP signal circuit to battery negative terminal. If either reading is less than 10,000 ohms, repair short circuit and repeat QUICK TEST  . If both readings are 10,000 ohms or more, replace ECA and repeat QUICK TEST  .
  7. Turn ignition off and wait 10 seconds. Harness disconnected at EVP and ECA. Connect breakout box and leave ECA disconnected. With DVOM on 200 ohm scale, measure continuity from box pin 46 to signal return circuit of EVP harness; from box pin 26 to voltage reference circuit of EVP harness and from box pin 27 to EVP signal circuit of EVP harness. If all readings less than 5 ohms, go to next step. If any reading 5 ohms or more, repair open circuit and repeat QUICK TEST  .
  8. Ignition off, EVP harness disconnected, breakout box installed and ECA disconnected. With DVOM on 200,000 ohm scale, measure resistance from box pin 27 to pins 37 and 57. If either reading is less than 10,000 ohms, repair short circuit and repeat QUICK TEST  . If both readings are 10,000 ohms or more, replace ECA and repeat QUICK TEST  .
  9. Codes 32, 33 and 34. Turn ignition off and wait 10 seconds. Enter Output State Check and perform KEY ON-ENGINE OFF (KOEO) SELF-TEST  until end of Continuous code display. DVOM will indicate zero volts. Depress and release throttle and observe DVOM. If DVOM registered high voltage, remain in Output State Check and go to next step. If DVOM did not register high voltage, depress throttle to wide open position and release. If voltage still does not register high reading, go to TEST D  , step 13).
  10. Turn ignition on (engine off). Remain in Output State Check. Disconnect and plug vacuum line at bottom port of EGR control solenoid and connect vacuum pump. Using a "Tee", connect vacuum gauge in top line at EGR valve. Disconnect but DO NOT  plug vacuum vent line at EGR vent solenoid. Apply vacuum and observe vacuum gauge while depressing and releasing throttle (cycling outputs on and off). If vacuum output cycles on and off in less than 2 seconds, reconnect vacuum lines and go to next step. If vacuum output does not cycle on and off in less than 2 seconds, replace solenoid assembly and repeat QUICK TEST  .
  11. Turn ignition off and wait 10 seconds. Remove all test equipment and reconnect all vacuum lines. Check EEC system vacuum lines for proper routing, leaks and obstructions. Repair as required. If vacuum lines are okay, service EGR system.
  12. Ignition off and harness disconnected at EVP sensor. Remove EVP sensor from EGR valve. With DVOM on 200,000 ohm scale, measure resistance from signal return circuit to voltage reference circuit at EVP sensor. Observe DVOM while slowly pushing EVP sensor shaft inward. If reading smoothly decreases from no more than 5500 ohms to no less than 100 ohms, replace EGR valve assembly and repeat QUICK TEST  . If reading does not decrease smoothly or changes suddenly, replace EVP sensor and repeat QUICK TEST  .
  13. Code 35 (RPM too low for EGR test). Before continuing, check for codes 12 and 13. If code 12 or 13 present, go to TEST K  . If no code 12 or 13, go to next step.
  14. Turn ignition off and wait 10 seconds. Install tachometer and perform KEY ON-ENGINE RUNNING (KOER) SELF-TEST  while maintaining engine speed at 1500 RPM. Record Key On-Engine Running service codes. If code 35 present, replace ECA and repeat QUICK TEST  . If no code 35, repeat QUICK TEST  and repair codes as required.
  15. Turn ignition off and wait 10 seconds. Disconnect EVP sensor and inspect harness and connector terminals. Repair as required. Turn ignition on (engine off). With DVOM on 20 volt scale, measure voltage from voltage reference circuit at sensor harness to battery ground. If reading is 4-6 volts, go to next step. If reading is less than 4 volts, go to step  7 . If reading is 6 volts or more, go to TEST C  .
  16. Ignition on and EVP sensor disconnected. With DVOM on 20 volt scale, measure voltage from voltage reference circuit to signal return circuit at sensor harness. If reading is 4-6 volts, go to next step. If reading is less than 4 volts, repair open circuit and repeat KEY ON-ENGINE OFF (KOEO) SELF-TEST  .
  17. Turn ignition off and wait 10 seconds. Disconnect 60-pin connector at ECA and inspect. Repair as required. Connect breakout box and reconnect ECA. Connect EVP sensor. Turn ignition on (engine off). With DVOM on 20 volt scale, measure voltage from box pin 27 to pin 46. If less than .5 volt, go to next step. If 1.25 volt or greater, go to step  21 .
  18. Turn ignition off and wait 10 seconds. Disconnect ECA and EVP sensor. Breakout box installed. With DVOM on 200 ohm scale, measure resistance from box pin 27 to pins 20, 40, 46 and 60 in turn. If 5 ohms or more, go to next step. If less than 5 ohms, repair short to ground in EVP signal circuit and repeat QUICK TEST  .
  19. Turn ignition off. Breakout box installed and ECA and EVP sensor disconnected. With DVOM on 200 ohm scale, measure resistance from box pin 27 to EVP signal circuit at sensor harness. If 5 ohms or more, repair open in EVP signal circuit and repeat QUICK TEST  . If less than 5 ohms, go to next step.
  20. Turn ignition off. Replace EVP sensor with known good sensor and reconnect harness. Remove breakout box and reconnect ECA. Perform KEY ON-ENGINE OFF (KOEO) SELF-TEST  . If code 31 present, replace ECA and reinstall original EVP sensor. If no code 31, testing is complete.
  21. Turn ignition off and wait 10 seconds. Disconnect 60-pin connector at ECA and connect breakout box. Leave ECA disconnected. Disconnect EVP sensor. With DVOM on 200 ohm scale, measure resistance from box pin 27 to pins 26, 37 and 57 in turn. If 5 ohms or more, go to next step. If less than 5 ohms, repair short to power and repeat KEY ON-ENGINE OFF (KOEO) SELF-TEST  .
  22. Turn ignition off and wait 10 seconds. Connect electrical harness to a known good EVP sensor and EGR valve assembly. Remove breakout box and reconnect ECA. Perform KEY ON-ENGINE OFF (KOEO) SELF-TEST  . If code 31, replace ECA, reconnect original EVP sensor and EGR valve assembly and repeat QUICK TEST  . If no code 31, go to next step.
  23. Turn ignition off and wait 10 seconds. Install original EVP sensor and connect harness. Perform KEY ON-ENGINE OFF (KOEO) SELF-TEST  . If code 31, install new EVP sensor. If no code 31, testing complete.
  24. Continuous Code 31. Disconnect vacuum line at EGR valve and install vacuum pump. Very slowly apply 6 in. Hg vacuum to sensor, then slowly bleed off vacuum. Enter Continuous Monitor mode and observe volt/ohmmeter for fault indication while doing the following: Lightly tap on EVP sensor to simulate road shock. Wiggle sensor connector. If fault is indicated, go to next step. If no fault indicated, go to step  26 .
  25. Turn ignition off and wait 10 seconds. Disconnect 60-pin connector at ECA and inspect. Repair as required. Connect breakout box and reconnect ECA. With volt/ohmmeter still connected to self-test output as in step  24 , connect DVOM between box pin 27 and pin 46. Turn ignition on (engine off). With DVOM on 20 volt scale, observe DVOM while repeating step  24 . If fault occurs below 4.25 volts, disconnect and inspect harness at EVP sensor. If connector and terminals are okay, replace EVP sensor and repeat QUICK TEST  . If fault does not occur below 4.25 volts, EGR valve "overshoot" may have caused code 31. Sensor service not required. Go to next step to verify harness integrity.
  26. Observe volt/ohmmeter while doing the following: Beginning at EVP, wiggle, shake or bend small sections of harness while working way to dash panel. Then repeating process from panel to ECA. If fault is indicated, isolate and repair problem and repeat QUICK TEST  . If no fault indicated, go to next step.
  27. Turn ignition off and wait 10 seconds. Disconnect 60-pin connector at ECA and inspect connector and terminals for damage. If damaged, service as required and repeat QUICK TEST  . If okay, fault cannot be duplicated at this time. Continuous Code 31 testing is complete.
Fig 1: EGR Valve Position (EVP) Sensor Circuit
G9343
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