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Circuit Test B11

NOTE: Perform this test when Service Code 31, 32, 33, 34, 35, 38 or 84 is displayed during QUICK TESTS or when directed here by other test procedures.
Fig 1: EGR Valve Position (EVP) Sensor & EGR Valve Regulator (EVR) Solenoid Circuits
G54783
  1. Code 31: Generate Code 35. Code 31 indicates that EVP signal is less than the Self-Test minimum of 0.2 volt. Turn key off and wait 10 seconds. Disconnect EVP harness at sensor. Install a jumper wire between VREF and EVP SIGNAL at sensor harness connector. Perform KOEO SELF-TEST. Check for code 35. Ignore all other codes at this time. If Code 35 is displayed, remove jumper and replace EVP sensor. Repeat QUICK TEST. If Code 35 is not displayed, remove jumper wire and go to next step.
  2. Checking VREF to SIG RTN Voltage. With KOEO and EVP disconnected, set DVOM on 20-volt scale. Measure voltage at EVP connector between VREF and SIG RTN. If reading is less than 4 or more than 6 volts, go to CIRCUIT TEST A3 , step 1). If reading is between 4 and 6 volts, go to next step.
  3. Checking EVP SIGNAL Continuity. With key off, wait 10 seconds. Disconnect EVP sensor, set DVOM on 200-ohm scale. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, and connect ECA to box. Measure resistance between EVP SIGNAL at connector and test pin No. 27. If reading is 5 ohms or more, repair open circuit. Connect EVP sensor and remove breakout box. Repeat QUICK TEST. If reading is less than 5 ohms, go to next step.
  4. Checking EVP SIGNAL For Shorts To Ground. With key off and EVP harness disconnected, leave breakout box installed and ECA disconnected. Set DVOM on 200K-ohm scale. Measure resistance between EVP signal at EVP connector and ground. Measure resistance between test pin No. 27 and test pins No. 40, 46 and 60. If any reading is less than 10K ohms, repair short circuit. Connect EVP and remove breakout box. Repeat QUICK TEST. If both readings are 10K ohms or more, replace ECA. Connect EVP and remove breakout box. Repeat QUICK TEST.
  5. Code 35: Generate Code 31. Code 35 indicates EVP signal is greater than the Self-Test maximum of 4.81 volts. Turn key off and wait 10 seconds. Disconnect EVP sensor. Inspect for and repair any damaged wiring. Perform KOEO SELF-TEST. Check for Code 31. Ignore all other codes at this time. If code 31 is not displayed, go to step 7). If Code 31 is displayed, go to next step.
  6. Checking VREF To SIG RTN Voltage. With EVP harness disconnected, set DVOM on 20-volt scale. With KOEO, measure voltage at EVP harness connector between VREF and SIG RTN. If reading is between 4 and 6 volts, replace EVP sensor. Repeat QUICK TEST. If reading is less than 4 volts or more than 6 volts, go to CIRCUIT TEST A3 , step 1).
  7. Checking EVP SIGNAL For Short To Power. Turn key off and disconnect EVP from harness. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200K-ohm scale. Measure resistance between test pin No. 27 and test pins No. 26 and 57. If either reading is less than 10K ohms, repair short in harness. Connect EVP sensor and remove breakout box. Repeat QUICK TEST. If both readings are 10K ohms or more, replace ECA. Connect EVP sensor and remove breakout box. Repeat QUICK TEST.
  8. Code 84: EVR Solenoid Resistance. Code 84 indicates a faulty EVR circuit. Turn key off. Set DVOM on 200-ohm scale. Disconnect EVR solenoid connector and measure solenoid resistance. If reading is less than 30 ohms or more than 70 ohms, replace EVR solenoid assembly. Repeat QUICK TEST. If reading is between 30 and 70 ohms, go to next step.
  9. Checking VPWR at EVR Solenoid. Leave EVR solenoid disconnected and set DVOM on 20-volt scale. Turn key on, leaving engine off. Measure voltage between negative battery terminal and VPWR circuit at EVR solenoid harness connector. If reading is less than 10.5 volts, repair VPWR open circuit. Repeat QUICK TEST. If reading is 10.5 volts or more, go to next step.
  10. EVR Circuit Continuity. With key off and EVR solenoid 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 No. 33 and EVR SIGNAL at EVR solenoid connector. If reading is 5 ohms or more, repair open circuit. Connect EVR solenoid and remove breakout box. Repeat QUICK TEST. If reading is less than 5 ohms, go to next step.
  11. Checking EVR Circuit Shorts. With key off, breakout box installed, and ECA and EVR solenoid disconnected, set DVOM on 200K-ohm scale. Measure resistance between test pin No. 33 and test pins No. 37 and 57, 40, 60, and 46 at breakout box. If any reading is less than 10K ohms, repair short circuit. Remove breakout box, and connect ECA and EVR solenoid. Repeat QUICK TEST. If code is repeated, replace ECA. If all readings are 10K ohms or more, replace ECA. Remove breakout box, and connect ECA and EVR solenoid. Repeat QUICK TEST.
  12. KOEO Code 34: Check For Code 84. KOEO Code 34 indicates EGR valve and/or EVP is not fully seated in the closed position. EVP voltage signal, in the closed position, is greater than the Self-Test maximum of 0.67 volt. Because of the preload on the installed EVP sensor it is very difficult to determine if the EGR valve is seated or the EVP sensor is in contact with the EGR valve. Turn key off and wait 10 seconds. Check for Code 84 in KOEO SELF-TEST. If Code 84 is present, go to step 8). If Code 84 is not displayed, go to next step.
  13. Functional Test of EVP Sensor and EGR Valve. Turn key off and wait 10 seconds. Disconnect EVP sensor. Inspect harness and connector, service as necessary. Remove vacuum line from EGR valve. Test EGR valve operation by applying and releasing vacuum to valve, using a vacuum pump. Reconnect vacuum line. Repeat KOEO and KOER SELF-TEST. If Code 34 is still displayed, go to next step. If Code 34 is not displayed, the original code was set by a faulty connection or a sticking EGR valve. Testing of EGR valve is complete.
  14. Substitute EVP Sensor on Original EGR Valve. Turn key off and wait 10 seconds. Install a good known EVP sensor on original EGR valve. Perform KOEO SELF-TEST. If Code 34 is present, check EGR valve for mechanical malfunction. If Code 34 is not present, replace original EVP sensor. Repeat QUICK TEST.
  15. KOEO and KOER Code 32 Checking EVP and EGR. Code 32 indicates that EGR valve and/or EVP sensor signal voltage is less than closed position minimum of 0.29 volt. Preload on EVP sensor makes it difficult to determine whether the EGR valve has malfunctioned or if the EVP sensor has abnormally high resistance. Possible causes for this fault are: poor continuity at EVP sensor connector, non-seated or faulty EGR valve or faulty EVP sensor. Turn key off and wait 10 seconds. Inspect connector and harness for damage and service as necessary. Remove vacuum line from EGR valve. Test EGR valve operation by applying and releasing vacuum to valve, using a vacuum pump. Reconnect vacuum line. If Code 32 is still present, go to next step. If Code 34 is not displayed, the original code was set by a faulty connection or a sticking EGR valve. Testing of EGR valve is complete.
  16. Substitute EVP Sensor On Original EGR Valve. Turn key off and wait 10 seconds. Install a known good EVP sensor on original EGR valve. Perform KOEO SELF-TEST. If Code 32 is present, check EGR valve for mechanical malfunction. If Code 32 is not present, replace original EVP sensor. Repeat QUICK TEST.
  17. KOER Code 33: Checking Vacuum at EGR. KOER Code 33 indicates that EVP sensor input did not change after ECA signaled EGR operation. Because a Code 84 was not received in the KOEO SELF-TEST, the EVR solenoid electrical function is okay. The lack of Code 32 or 34 indicate the EVP sensor is within the closed position specifications. Possible causes for this fault are; leaking vacuum hose, restricted vacuum hose, restricted EVR solenoid filter, or a faulty EGR valve. Turn key off. Using vacuum "T", connect vacuum gauge at EGR valve. Perform KOER SELF-TEST and observe vacuum gauge. If reading is 1.5 in. Hg or greater, go to step 20). If reading is less than 1.5 in. Hg, remove vacuum gauge and reconnect EGR valve, or go to next step.
  18. Checking Vacuum Supply to EVR Solenoid. Turn key off. Disconnect vacuum source to EVR solenoid. Install vacuum gauge at source vacuum hose. Start engine. If reading is 10 in. Hg or more, go to next step. If reading is less than 10 in. Hg, check vacuum hose to EVR solenoid. Replace if necessary. Repeat QUICK TEST.
  19. Checking Vacuum Hoses. Carefully check vacuum line for cracks, loose connections, blockage, kinks, and leaks. If vacuum hose is not okay, replace hose. Connect new vacuum hose and repeat QUICK TEST. If vacuum hose is okay, check EVR solenoid filter for obstructions. Replace if necessary. If filter is okay, replace EVR solenoid. Connect all vacuum hoses and repeat QUICK TEST.
  20. Checking EVP Sensor and EGR Valve. Turn key off and wait 10 seconds. Disconnect EVP sensor. Inspect connector and harness or damage and service as necessary. Remove vacuum line from EGR valve. Test EGR valve operation by manually depressing and releasing the diaphragm. Reconnect vacuum line to EGR valve and connector to EVP sensor. Repeat KOEO and KOER SELF-TEST. If Code 33 is still present, go to next step. If Code 33 is not displayed, the original code was set by poor continuity or a sticking EGR valve. Testing of EGR valve is complete.
  21. Checking EGR Valve Vacuum Control. With key off, disconnect EGR valve vacuum supply. Connect a vacuum gauge to EGR valve and apply 2-3 in. Hg for 2 minutes. If EGR holds vacuum, reconnect supply line and go to next step. If EGR valve will not hold vacuum, service or replace EGR valve.
  22. Substitute Known Good EVP Sensor. Turn key off and wait 10 seconds. Install a known good EVP sensor on original EGR valve. Perform KOER SELF-TEST. If Code 33 is present, check EGR valve and/or system for mechanical malfunction. If Code 33 is not present, service or replace original EVP sensor. Repeat QUICK TEST.
  23. Code 34: EGR Valve Operation. Code 34 indicates that EVP voltage is greater than closed position Self-Test minimum of 0.67 volts. Turn key off. Disconnect and plug EGR valve vacuum hose. Perform KOER SELF-TEST. If Code 34 is not present, check EVR filter for obstructions. Replace if necessary. If filter is okay, replace EVR solenoid. Connect all vacuum hoses and repeat QUICK TEST. If Code 34 is present, go to next step.
  24. Checking EVP Resistance, While Applying Vacuum to EGR. Turn key off and wait 10 seconds. Disconnect harness from EVP sensor. Inspect connectors for damaged pins or corrosion. Repair if necessary. Set DVOM on 200K-ohm scale. Disconnect vacuum hose to EGR valve and connect vacuum pump to valve. Measure resistance at EVP sensor between EVP SIGNAL and VREF while gradually increasing vacuum to 10 in. Hg. If reading decreases from no more than 5500 ohms to no less than 100 ohms, check EGR valve for mechanical malfunction and service or replace as necessary. If reading does not change as indicated, replace EVP sensor. Reconnect vacuum hose and rerun QUICK TEST.
  25. Continuous Memory Code 32: Check EVP Signal Voltage While Operating EGR. Code 32 indicates that EGR valve closed further than normal with engine at idle and at normal operating temperature. 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. Connect vacuum pump to EGR valve. Place DVOM on 20-volt scale and connect between test pins No. 27 and 46. With KOEO, observe DVOM readings. Slowly apply 6 in. Hg vacuum to EGR valve. Slowly bleed vacuum off EGR valve and lightly tap on EVP sensor to simulate road shock. If voltage drops to less than .29 volt, the EGR valve may have caused Code 32. Clear Continuous Memory Codes. Check EGR valve for mechanical malfunction. If all readings are more than .29 volt, Code 32 fault cannot be duplicated at this time. Testing is complete.
  26. Continuous Memory Code 31 and/or 35: Check Harness. Code 31 indicates an open in the EVP SIGNAL or VREF, or a short to SIG RTN with the engine at idle and at normal operating temperature. Code 35 indicates a short to VREF and/or VPWR, or an open in SIGNAL RETURN with the engine at idle and at normal operating temperature. Using KOEO CONTINUOUS MONITOR (WIGGLE) TEST, observe VOM or diagnostic tester for fault indication while grasping harness close to sensor and wiggling, shaking, or bending a small section of EEC-IV harness while working toward dash panel. Wiggle, shake or bend harness from firewall to ECA. If fault is indicated, isolate fault and repair wiring harness as required. Repeat QUICK TEST. If fault is not found, go to next step.
  27. Checking ECA and Harness Connectors. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector and terminals for obvious damage. If connector and terminals are damaged, repair as necessary. Repeat QUICK TEST. If connector and terminals are okay, fault cannot be duplicated at this time. Test is completed.
  28. Continuous Memory Code 33: Leak Test. Code 33 indicates that EGR valve did not open with the engine at normal operating temperature and with the EVR solenoid signal present. Turn key off and wait 10 seconds. Connect vacuum pump to EGR valve. Apply 20 in. Hg to EGR valve. If EGR valve opens and holds vacuum, go to next step. If not, service or replace EGR valve as necessary, clear codes and repeat QUICK TEST.
  29. EVR Check. Using CONTINUOUS MONITOR (WIGGLE) TEST, observe VOM or diagnostic tester for fault indication. Grasp harness close to EVR solenoid connector and wiggle, shake, or bend a small section of harness while working toward ECA. Inspect connectors and terminals for obvious damage. If fault is indicated, isolate fault and repair as necessary. Repeat QUICK TEST. If no fault is indicated, fault cannot be duplicated at this time. Testing is complete.
  30. Continuous Memory Code 34: EVP Resistance Check While Operating EGR Valve. Code 34 indicates EGR valve was open with the engine idling at normal operating temperature. Turn key off. Disconnect harness from EVP sensor. Inspect connector for obvious damage. Place DVOM on 200K-ohm scale. Disconnect vacuum hose to EGR valve and connect vacuum pump to valve. Measure resistance at EVP sensor between EVP SIGNAL and VREF at the sensor while increasing vacuum to 10 in. Hg. If reading does not decrease gradually from up to 5500 ohms to not less than 100 ohms, check EGR valve for mechanical malfunction. If reading gradually decreases from no more than 5500 ohms to no less than 100 ohms, go to next step.
  31. EVR Check. Turn key off. Disconnect vacuum hose from EGR valve and plug hose. Perform KOER SELF-TEST. If Code 34 is present, check EVR filter for obstructions. Replace if necessary. If filter is okay, replace EVR solenoid. Connect all vacuum hoses and repeat QUICK TEST. If Code 34 is not present, fault cannot be duplicated at this time. Testing is completed.
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