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HOMESERVICE MANUALSFORD1985THUNDERBIRD BASE, 2.3 W, AUTOMATICREPAIR AND DIAGNOSISENGINE PERFORMANCETESTING & DIAGNOSIS1.6L & 2.3L EFI/TURBO TESTSTESTINGTEST F - EGR VALVE POSITION SENSOR (EVP) CONTROL/VENT EGRC/EGRV
1985 Ford Thunderbird Base, 2.3 W, Automatic

Test F - EGR Valve Position Sensor (EVP) Control/Vent EGRC/EGRV

1985 Ford Thunderbird Base, 2.3 W, AutomaticSECTION Test F - EGR Valve Position Sensor (EVP) Control/Vent EGRC/EGRV
  1. Code 31 Displayed. Turn key off and wait 10 seconds. Disconnect and plug vacuum line at EGR valve. Perform KEY ON/ENGINE RUNNING (KOER) SELF-TEST PROCEDURE  . If code 31 is displayed go to next step. If code 31 is not displayed but codes 32 and 34 are, go to step 8).
  2. Turn key off and wait 10 seconds. Leave EGR vacuum line disconnected and plugged. Disconnect EVP sensor harness. Set DVOM on 200,000 ohm scale and connect vacuum pump to EGR valve. Measure resistance between EVP signal and VREF at EVP connector while vacuum is slowly increased to 10 in. Hg. If reading is less than 100 ohms or more than 5500 ohms, replace EVP sensor, connect vacuum signal line and harness. Repeat QUICK TEST  . If reading does not decrease or valve does not hold vacuum, go to step 13). If reading gradually decreases from a maximum of 5500 ohms to a minimum of 100 ohms, go to next step.
  3. Turn key on, leaving engine off. Disconnect and plug vacuum signal line and disconnect EVP sensor harness. Set DVOM on 20-volt scale. Measure voltage between VREF and signal return at EVP connector. If reading is less than 4.0-volts or higher than 6.0 volts, go to TEST C, Step 1). If reading is between 4.0 and 6.0 volts, go to next step.
  4. Turn key off and wait 10 seconds. Disconnect 60-pins connector at ECA and harness at EVP sensor harness. Set DVOM to 20 damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin 27 and EVP signal at EVP connector. If reading is 5 ohms or higher, repair open in circuit. Remove breakout box, connect ECA and EVP sensor, then repeat QUICK TEST  . If reading is less than 5 ohms, go to next step.
  5. Turn key off and disconnect harness at EVP sensor. Install breakout box, leaving ECA disconnected. Set DVOM on 200,000 ohm scale. Measure resistance between test pin 27 and test pins 26, and 46. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, connect ECA and EVP sensor, then repeat QUICK TEST  . If all readings are 10,000 ohms or higher, go to next step.
  6. Turn key off and wait 10 seconds. Connect known good EVP sensor and EGR valve assembly to harness and vacuum lines. Remove breakout box and connect ECA. Perform KEY ON/ENGINE OFF (KOEO) SELF-TEST PROCEDURE  . If code 31 is displayed, replace ECA. Connect original EVP sensor and EGR valve assembly. Repeat QUICK TEST  . If code 31 is not displayed, go to next step.
  7. Turn key off and wait 10 seconds. Install original EVP sensor to known good EGR valve. Connect EVP sensor and perform KEY ON/ENGINE OFF (KOEO) SELF-TEST PROCEDURE  . If code 31 is displayed, replace EVP sensor and repeat QUICK TEST  . If code 31 is not displayed, service EGR system.
  8. Codes 32, 33, or 34 Displayed. Use DVOM for this step, DO NOT  use STAR tester. Turn key off and wait 10 seconds. Set DVOM on 20-volt scale. Connect DVOM negative test lead to STO and positive lead to battery positive post. Connect jumper wire between STI and signal return. Perform KEY ON/ENGINE OFF (KOEO) SELF-TEST PROCEDURE  until end of CONTINUOUS SELF-TEST codes (DVOM reads 0-volts). Depress and release throttle. If reading does not change to high voltage, depress throttle to WOT and release. If STO voltage does not go high, go to TEST NN  , Step 13). If DVOM reading does go high, stay in OUTPUT STATE CHECK and go to next step.
  9. Turn key on, leaving engine off. Stay in OUTPUT STATE CHECK with DVOM set to 20-volt scale. Connect DVOM between EGRV solenoid, VPWR and EGRV signal. Depress and release throttle several times to cycle output on and off while observing DVOM. Repeat check for EGRC solenoid, VPWR and EGRC signal. If either solenoid does not cycle on and off, exit OUTPUT STATE CHECK and go to step 15). If both solenoids cycle on and off, stay in OUTPUT STATE CHECK and go to next step.
  10. Turn key on, leaving engine off. Stay in OUTPUT STATE CHECK. Disconnect and plug vacuum line from bottom port of EGRC solenoid. Connect vacuum pump to open port. Connect vacuum gauge in common output (upper) vacuum line to EGR valve. Disconnect, and leave open, vacuum vent line from EGRV solenoid. Maintain source vacuum and cycle output on and off by depressing and releasing throttle. If vacuum cycles ON and OFF in less than 2 seconds, reconnect all vacuum lines and go to step 12). If vacuum does not cycle ON and OFF in less than 2 seconds, go to next step.
  11. Stay in Output State mode. Repeat procedures in step 10). If vacuum output cycles ON and OFF in less than 2 seconds, replace filter (if equipped) and/or check vent line for blockage. After repairs, reconnect all vacuum lines. Repeat QUICK TEST  . If vacuum does not cycle ON and OFF in less than 2 seconds, replace solenoid assembly. Reconnect all vacuum lines. Repeat QUICK TEST  .
  12. Turn key OFF and wait 10 seconds. After reconnecting all vacuum lines, check ENTIRE EEC-IV vacuum line system for blockage or damage. Use VECI decal for emission schematic. If any lines are bad, repair and repeat QUICK TEST  . If lines are good, go to next step.
  13. With key off, disconnect EVP sensor harness. Inspect for and repair any damaged wiring. Set DVOM on 200,000 ohm scale. Disconnect vacuum line at EGR valve and connect vacuum pump to valve. Measure resistance of EVP sensor between EVP signal and VREF terminals while increasing vacuum to 10 in. Hg. If reading slowly decreases from maximum of 5500 ohms to minimum of 100 ohms, replace ECA. Connect EVP sensor and EGR vacuum line. Repeat QUICK TEST  . If reading does not slowly decrease, go to next step.
  14. With key off and harness disconnected from EVP sensor. Remove EVP sensor and vacuum line from EGR valve. Measure resistance of EVP sensor between EVP signal and VREF terminals. Observe resistance changes as EVP sensor shaft is slowly pushed in and slowly released. If both readings increase and decrease smoothly in range of 100-5500 ohms, replace EGR valve assembly. Connect EVP sensor and EGR vacuum line. Repeat QUICK TEST  . If either reading changes abruptly during range of 100-5500 ohms, replace EVP sensor. Reconnect harness and EGR vacuum line. Repeat QUICK TEST  .
  15. Turn key off and wait 10 seconds. Set DVOM on 200-ohm scale. Disconnect EGRC and EGRV solenoids from harness. Inspect for and repair any damaged wiring. Measure resistance of both solenoids. If either reading is less than 30 ohms or more than 70 ohms, replace EGRC/EGRV solenoid assembly. Repeat QUICK TEST  . If both readings are between 30 and 70 ohms, reconnect solenoids and go to next step.
  16. Disconnect EGRC and EGRV solenoids from harness. Turn key on, leaving engine off. Set DVOM on 20-volt scale. Measure voltage between battery negative terminal and VPWR circuit for both solenoids. If either reading is less than 10.5-volts, repair open circuit and repeat QUICK TEST  . If both readings are 10.5-volts or more, go to next step.
  17. Turn key off and wait 10 seconds. Leave EGRC and EGRV solenoids disconnected. 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 33 and EGRV signal at EGRV solenoid connector. Measure resistance between test pin 52 and EGRC signal at EGRC solenoid connector. If either reading is 5 ohms or more, repair open circuit. Remove breakout box, connect ECA and solenoids, then repeat QUICK TEST  . If both readings are less than 5 ohms, go to next step.
  18. Turn key off and wait 10 seconds. Set DVOM on 200,000 ohm scale. Install breakout box, leaving ECA disconnected. Disconnect EGRC and EGRV solenoids. Measure resistance between test pin 33 and/or 52 and test pins 40, 46, and 60. If readings are less than 10,000 ohms, repair short to ground. Repeat QUICK TEST  . If readings are 10,000 ohms or more, go to next step.
  19. With key off, disconnect EGRC and EGRV solenoids from harness. Install breakout box, leaving ECA disconnected. Set DVOM on 200,000 ohm scale. Measure resistance between test pin 33 and test pins 37 and 57. Measure resistance between test pin 52 and test pins 37 and 57. If any reading is less than 10,000 ohms, repair short in circuit. Remove breakout box and connect ECA. Repeat QUICK TEST  . If code is repeated, replace ECA. If all readings are 10,000 ohms or more, replace ECA. Remove breakout box and connect ECA. Repeat QUICK TEST  .
  20. Code 35 Displayed. This code indicates that engine RPM is too low for correct EGR testing. If code 12 is also displayed, go to:
    • TEST Z, step 1) - for EFI models with air by-pass.
    • TEST AA, step 1) - for models with DC motor control.
    • TEST BB, Step 1) - for models with throttle kicker.

    If code 12 is not displayed with code 35, go to next step.

  21. Turn key off and wait 10 seconds. Install tachometer. Perform KEY ON/ENGINE RUNNING (KOER) SELF-TEST PROCEDURE  at 1500 RPM. Record ENGINE RUNNING service codes. If code 35 is displayed, replace ECA and repeat QUICK TEST  . If code 35 is not displayed, repeat the QUICK TEST  and repair codes as necessary.
  22. Continuous Code 31 Displayed. Using CONTINUOUS MONITOR (WIGGLE) TEST  , observe VOM or STAR tester LED for indication of fault while doing the following: connect vacuum pump to EGR valve. Very slowly apply 6 in. Hg vacuum to EGR valve. Bleed vacuum slowly and lightly tap on EVP sensor. Wiggle EVP sensor connector. If fault is indicated, go to next step. If no fault is indicated, go to step 24).
  23. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box and connect ECA. Stay in CONTINUOUS MONITOR (WIGGLE) TEST  . Connect DVOM between test pins 27 and 46. Set DVOM on 20-volt scale. Turn key on, leaving engine off. Repeat step 22) while watching voltage. If fault occurs below 4.25-volts, disconnect EVP sensor from harness. Inspect for and repair any damaged wiring. If wiring is good, replace EVP sensor. Repeat QUICK TEST  . If fault does not occur below 4.25-volts, EGR valve overshoot may have caused continuous code 31. Sensor test is complete. Go to next step for harness test.
  24. While in CONTINUOUS MONITOR (WIGGLE) TEST  , bend, shake, and wiggle small sections of EEC-IV harness from sensor to firewall and from firewall to ECA. If fault is indicated, isolate fault and repair as necessary. Repeat QUICK TEST  . If no fault is indicated, go to next step.
    Fig 1: EVP, EGRC & EGRV Solenoid Circuits
    G2545
  25. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect both connector and terminals for obvious damage. If connector and terminals are damaged, repair as necessary, then repeat QUICK TEST  . If connector and terminals are okay, fault cannot be duplicated at this time. Continuous code 31 testing is complete.
RENDER: 1.0x

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