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Test B4 - EVP, EGRC, EGRV

NOTE: Perform this test when Service Code 31, 32, 33, 34, 35, 83, or 84 is displayed during QUICK TESTS or when directed here by other test procedures.
Fig 1: EVP, EGRC & EGRV Solenoid Circuits
G120720
EVP SENSOR SPECIFICATIONS

EGR Valve Opening (%) EVP Sensor Voltage
0 0.40
10 0.75
20 1.10
30 1.45
40 1.80
50 2.15
60 2.50
70 2.85
80 3.20
90 3.55
100 3.90

To prevent replacement of good components, be aware that the following non-EEC related area may be at fault: damaged EGR valve.

  1. KOER Service Code 31: Perform Engine Running Self-Test With EGR Vacuum Signal Line Disconnected at EGR Valve. Code 31 indicates that during KOER SELF-TEST, EVP sensor signal to ECA is out of range with the EGR valve closed. Possible causes are: a faulty EGRC/EGRV solenoids or a clogged EGRV filter. Turn key off and wait 10 seconds. Disconnect and plug vacuum line at EGR valve. Repeat KOER SELF-TEST. If Code 31 is not displayed, reconnect vacuum and go to step 8). If Code 31 is displayed, go to next step. Ignore all other service codes at this time.
  2. KOEO Service Code 31: Checking EVP Resistance With Vacuum Applied To EGR Valve. Code 31 displayed during the KOEO SELF-TEST indicates that the EVP sensor signal to ECA is out of range with the EGR valve closed. Possible causes are: an open or shorted circuit, faulty EGR valve, faulty EVP sensor, or a faulty ECA. Turn key off and wait 10 seconds. Leave EGR vacuum line disconnected and plugged. Disconnect EVP sensor harness. Set DVOM on 200K-ohm scale and connect vacuum pump to EGR valve. Measure resistance at EVP sensor between EVP and VREF terminals while vacuum is slowly increased to 10 in. Hg. See Fig 1 . If reading is less than 100 ohms or more than 5500 ohms, replace EVP sensor. Connect vacuum line and harness. Repeat QUICK TEST. If reading does not decrease or valve does not hold vacuum, go to step 11). If reading gradually decreases from a maximum of 5500 ohms to a minimum of 100 ohms, go to next step.
  3. Checking for VREF At The EVP. With KOEO, disconnect harness from EVP sensor. Set DVOM on 20-volt scale. Measure voltage between VREF and SIG RTN at EVP harness connector. See Fig 1 . If reading is not 4-6 volts, go to TEST A3 - REF  . VOLTAGE, step 1). If reading is 4-6 volts, go to next step.
  4. Checking EVP Signal Circuit Continuity. Turn key off and wait 10 seconds. Disconnect harness at EVP sensor and ECA 60-pin connector. Inspect and repair as necessary. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 27 at breakout box and EVP SIG at EVP harness connector. See Fig 1 . If reading is 5 ohms or more, repair open in circuit. Remove breakout box, connect ECA and EVP sensor, and repeat QUICK TEST. If reading is less than 5 ohms, go to next step.
  5. Checking EVP Signal for Shorts To VREF And SIG RTN. Turn key off and disconnect EVP sensor. Install breakout box, leaving ECA disconnected. Set DVOM on 200K-ohm scale. Measure resistance between test pin No. 27 and test pins No. 26, 40, 46, and 60 at breakout box. If any reading is less than 10K ohms, repair short circuit. Remove breakout box, connect ECA and EVP sensor. Repeat QUICK TEST. If all readings are 10K ohms or more, go to next step.
  6. EVP Sensor and EGR Valve Substitution Test. Turn key off and wait 10 seconds. Connect known good EVP sensor and EGR valve assembly to harness and vacuum lines. Connect ECA to breakout box. Perform KOEO SELF-TEST. 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. Testing EVP Sensor. Turn key off and wait 10 seconds. Ensure breakout box is installed and ECA connected to it. Use original EVP sensor on a known good EGR valve. Connect harness to EVP sensor and perform KOEO SELF-TEST. If Code 31 is displayed, replace EVP sensor and repeat QUICK TEST. If Code 31 is not displayed, remove breakout box, connect ECA and service EGR system.
  8. Codes 32, 33, or 34 Displayed. Codes 32, 33 or 34 indicate that the EGR valve did not open when instructed to by the ECA. Code 34 indicates the valve would not open. Code 32 indicates unable to hold valve open. Code 33 indicates unable to close valve correctly. Possible causes are: faulty vacuum lines, clogged EGRV filter, faulty EVP sensor, EGR valve, EGRC/EGRV solenoid or ECA. With key off, disconnect vacuum line at EGR valve. Connect a vacuum gauge to the vacuum line, leaving the EGR valve disconnected. Observe vacuum gauge while running KOER SELF-TEST. Disregard all other codes produced during this test. If vacuum reading increased from less than one in. Hg to greater than 5 in. Hg, within 10 seconds and returned to less than one in. Hg, go to step 10). If vacuum did not increase, remove vacuum gauge and go to next step. If vacuum increased but did not return to less than one in. Hg within 10 seconds, check EGRV filter for obstructions and replace as necessary. If filter is okay, replace solenoid assembly. Reconnect all vacuum lines and repeat QUICK TEST.
  9. Checking Vacuum Supply to EGRC/EGRV Solenoids. With key off, disconnect vacuum source to EGRC/EGRV solenoids. Install a vacuum gauge at the source vacuum line. Start engine and check vacuum. If vacuum is greater than 10 in. Hg, check vacuum line from EGRC/EGRV solenoids to EGR valve for blockage, leaks or damage, repair or replace as necessary. If supply line is okay, replace solenoid assembly and repeat QUICK TEST. If vacuum was less than 10 in. Hg, check vacuum source to EGRC/EGRV solenoids and repair as necessary. Reconnect vacuum lines and repeat quick test.
  10. Checking EVP Resistance. With key off, disconnect EVP sensor harness. Inspect for and repair any damaged wiring. Set DVOM on 200K-ohm scale. Disconnect vacuum line at EGR valve and connect vacuum pump to valve. Measure resistance of EVP sensor between EVP and VREF terminals while increasing vacuum to 10 in. Hg If resistance gradually changes between 5500 ohms and 100 ohms, replace ECA. Reconnect EVP sensor and EGR vacuum line. Repeat QUICK TEST. If reading does not change as specified, go to next step.
  11. Manual Test of EVP Sensor. With key off, disconnect EVP sensor harness. Remove EVP sensor and vacuum line from EGR valve. Measure resistance of EVP sensor at EVP and VREF terminal while sensor shaft is slowly pushed and slowly released. If resistance changes gradually between 5500 and 100 ohms, service EGR system. Reconnect EVP sensor and EGR vacuum line. Repeat QUICK TEST. If resistance did not change as specified, replace EVP sensor. Reconnect harness and EGR vacuum line. Repeat QUICK TEST.
    NOTE: It is normal for EVP sensor total resistance to drop to less than 100 ohms when disconnected from EGR valve. A defective sensor will change resistance suddenly between 5500 and 100 ohms.
  12. Service Code 83 or 84: Checking EGRV/EGRC Solenoid Resistance. A Code 83 indicates an EGRC circuit failure. A Code 84 indicates an EGRV circuit failure. Possible causes are: an open or shorted circuit, faulty EGRC/EGRV solenoid or ECA. Turn key off and wait 10 seconds. Set DVOM on 200-ohm scale. Disconnect EGRV and EGRC solenoids from harness. Inspect 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, go to next step.
  13. Check For VPWR At EGRC/EGRV Solenoids. 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 on both EGR solenoid harness connectors. See Fig 1 . If either reading is less than 10.5 volts, repair open circuit, reconnect solenoids and repeat QUICK TEST. If both readings are 10.5 volts or more, go to next step.
  14. Continuity Check Of EGRC/EGRV Circuits. Turn key off and wait 10 seconds. Disconnect EGRC/EGRV solenoids. Disconnect ECA 60-pin connector. Inspect and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 33 of breakout box and EGRV circuit at EGRV solenoid harness connector. See Fig 1 . Measure resistance between test pin No. 52 and EGRC circuit at EGRC solenoid harness connector. If either reading is 5 ohms or more, repair open circuit. Remove breakout box, reconnect components, and repeat QUICK TEST. If both readings are less than 5 ohms, go to next step.
  15. Checking EGRC/EGRV Circuits For Short To Ground. Turn key off and wait 10 seconds. Set DVOM on 200K-ohm scale. Install breakout box, leaving ECA disconnected. Disconnect EGRC and EGRV solenoids. Measure resistance between test pin No. 33 and test pins No. 40, 46, and 60 of breakout box. Measure resistance between test pin No. 52 and test pins No. 40, 46, and 60. If any reading is less than 10K ohms, repair short to ground. Remove breakout box, reconnect components and repeat QUICK TEST. If all readings are 10K ohms or more, go to next step.
  16. Checking For Shorts To Power. With key off, disconnect EGRC and EGRV solenoids from harness. Install breakout box, leaving ECA disconnected. Set DVOM on 200K-ohm scale. Measure resistance between test pin No. 33 and test pins No. 37 and 57 at breakout box. Measure resistance between test pin No. 52 and test pins No. 37 and 57 at breakout box. If any reading is less than 10K ohms, repair short in circuit. Remove breakout box, reconnect components and repeat QUICK TEST. If all resistances are greater than 10K ohms, replace ECA. Remove breakout box, reconnect components and repeat QUICK TEST.
  17. Service Code 35: Check For Code 12. This code indicates that engine RPM was too low perform EGR test. Possible causes are: faulty ISC system or faulty ECA. If Code 12 is also displayed go to TEST D5 - ISC  , step 1). If Code 12 is not displayed with Code 35, go to next step.
  18. Retest at 1500 RPM. Turn key off and wait 10 seconds. Install tachometer. Perform KOER SELF-TEST at 1500 RPM. Ignore all other codes at this time. If code 35 is still displayed, replace ECA, clear codes and repeat QUICK TEST. If code 35 is not displayed, repeat QUICK TEST and repair any other codes as necessary.
  19. Continuous Memory Code 31. Continuous Code 31 indicates that sometime during vehicle operation the EVP signal was out of the Self-Test range. Possible causes are: an open or shorted circuit or a faulty EVP sensor. Using KOEO CONTINUOUS MONITOR (WIGGLE) TEST, observe VOM or diagnostic tester 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 21).
  20. EVP Signal Voltage During Operation Of EVP Sensor. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect and repair any damaged wiring. Install breakout box and connect ECA to it. Connect DVOM between test pins No. 27 and 46. Set DVOM on 20-volt scale. Re-enter KOEO CONTINUOUS MONITOR (WIGGLE) TEST. Monitor DVOM and repeat step 19). If fault occurs below 4.25 volts, disconnect EVP sensor from harness. Inspect for and repair any damaged wiring. If wiring is okay, replace EVP sensor. Clear continuous memory and repeat QUICK TEST. If fault does not occur below 4.25 volts, EGR valve overshoot may have caused Continuous Memory Code 31. Sensor test is complete. Go to next step for harness test.
  21. Checking EEC-IV Harness. While in KOEO 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. Clear codes and repeat QUICK TEST. If no fault is indicated, go to next step.
  22. Checking ECA and Harness Connectors. 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 and repeat QUICK TEST. If connector and terminals are okay, fault cannot be duplicated at this time. Continuous Code 31 testing is complete.
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