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Home >> Ford >> 1989 >> Bronco II RWD, Standard, M5OD-R1 >> Repair and Diagnosis >> Engine Performance >> System >> 2.9L CEC Tests W/Codes >> Circuit Test >> Test B11 - EVP, EVR

Test B11 - EVP, EVR

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: EVP Sensor & EVR Solenoid Circuits
G120726
  1. Service 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 EVP 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 harness connector between VREF and SIG RTN. If reading is less than 4 or more than 6 volts, go to TEST A3 - REF  . VOLTAGE, step 1). If reading is between 4 and 6 volts, go to next step.
  3. Checking EVP SIGNAL Continuity. Turn 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 harness connector and test pin No. 27 at breakout box. 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 test pin No. 27 and test pins No. 40, 46 and 60 at breakout box. If any reading is less than 10K ohms, repair short circuit(s). Remove breakout box, reconnect components and repeat QUICK TEST. If all readings are 10K ohms or more, replace ECA. Connect EVP and remove breakout box. Repeat QUICK TEST.
  5. Service Code 35: Attempt To Generate Code 31. Code 35 indicates EVP signal is greater than the Self-Test maximum of 4.81 volts. Possible causes are: faulty EVP sensor or short to power in harness. Turn key off and wait 10 seconds. Disconnect EVP sensor. 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. See Fig 1 . If reading is 4-6 volts, replace EVP sensor. Repeat QUICK TEST. If reading is not 4-6 volts, go to TEST A3 - REF  . VOLTAGE, step 1).
  7. Checking EVP SIGNAL For Short To Power. Turn key off and disconnect EVP. Disconnect ECA 60-pin connector. Inspect 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 at breakout box. If either reading is less than 10K ohms, repair short in harness. Remove breakout box, reconnect components and repeat QUICK TEST. If both readings are 10K ohms or more, replace ECA. Reconnect components and remove breakout box. Repeat QUICK TEST.
  8. Service Code 84: Checking EVR Solenoid Resistance. Code 84 indicates a faulty EVR circuit. Possible causes are: faulty EVR solenoid, open or shorted harness or faulty ECA. Turn key off and wait 10 seconds. Set DVOM on 200-ohm scale. Disconnect EVR solenoid and measure solenoid resistance. If reading is not between 30 and 70 ohms, replace EVR solenoid assembly. Repeat QUICK TEST. If reading is between 30 and 70 ohms, go to next step.
  9. Check For 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. See Fig 1 . 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. Check EVR Circuit Continuity. With key off and EVR solenoid disconnected, 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 and EVR SIGNAL at EVR solenoid harness connector. See Fig 1 . If reading is 5 ohms or more, repair open circuit. Remove breakout box, reconnect components and repeat QUICK TEST. If reading is less than 5 ohms, go to next step.
  11. Checking EVR Circuit For Short To Power And Ground. 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. 37/57, 40/60, and 46 at breakout box. If any reading is less than 10K ohms, repair short circuit(s). Remove breakout box, reconnect components and repeat QUICK TEST. If code is repeated, replace ECA. If all readings are 10K ohms or more, replace ECA. Remove breakout box, reconnect components and repeat QUICK TEST.
  12. KOEO Code 34: Check For Service 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 stem. Possible causes are: poor continuity at EVP sensor, non-seated EGR valve, faulty EGR valve or faulty EVP sensor. 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 to EGR and reconnect EVP sensor. 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 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 still 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 Sensor and EGR Valve. Code 32 indicates that EGR valve and/or EVP sensor lower than normal in the closed position. The EVP voltage is less than closed limit voltage 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 are: poor continuity at EVP sensor connector, non-seated or faulty EGR valve or faulty EVP sensor. Turn key off and wait 10 seconds. Disconnect EVP sensor. 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 to EGR and reconnect EVP sensor. Perform KOEO and KOER SELF-TEST. 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 Service Code 33: Checking Vacuum at EGR Valve. 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 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 vacuum source. Start engine. If vacuum 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 electrical 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 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, 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. Service Code 34: EGR Valve Operation, KOER SELF-TEST With EGR Vacuum disconnected. Code 34 indicates that EVP voltage is greater than closed limit voltage of 0.67 volts. Possible causes are: obstructed EVR solenoid filter, faulty EVR solenoid, faulty EGR valve or EVP sensor. 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 and replace if necessary. If filter is okay, replace EVR solenoid assembly. Reconnect 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 as 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 gradually 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 repeat QUICK TEST.
  25. Continuous Memory Code 32: Check EVP Signal Voltage While Operating EVP Sensor. Code 32 indicates that EGR valve closed further than normal with engine at idle and at normal operating temperature or that EVP sensor has failed with an intermittent low voltage spike symptom. 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. Disconnect EGR valve vacuum hose and connect vacuum pump to EGR valve. Set DVOM on 20-volt scale and connect between test pins No. 27 and 46 at breakout box. With KOEO, observe DVOM readings. Slowly apply 6 in. Hg vacuum to EGR valve. Slowly bleed vacuum off EGR valve while lightly tapping on EVP sensor (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 and repair or replace as necessary. If voltage does not drop to less than .29 volt, Code 32 fault cannot be duplicated at this time. Testing is complete.
  26. Continuous Memory Code 32/31: Check EVP Sensor While In Continuous Monitor Mode. Code 31 indicates sometime during vehicle operation, EVP signal was out of SELF-TEST range. Possible causes are: open or shorted circuit or faulty EVP sensor. Enter KOEO CONTINUOUS MONITOR (WIGGLE) TEST. Observe VOM or diagnostic tester for fault indication while very slowly applying 6 in. Hg vacuum to EGR valve. Slowly bleed vacuum off EGR valve and lightly tap EVP sensor (simulate road shock). Wiggle EVP sensor connector. If fault is indicated, go to next step. If no fault is indicated, go to step 28).
  27. Measure EVP Signal Voltage While Operating EVP Sensor. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector and terminals for obvious damage and repair as necessary. Install breakout box and connect ECA to it. Set DVOM on 20 volt scale. Connect DVOM between test pin 27 and 46 at breakout box. Enter KOEO CONTINUOUS MONITOR test. While observing DVOM, repeat step 26). If fault occurs below 4.25 volts, disconnect and check connectors. If connectors are okay, replace EVP sensor. Clear continuous memory and repeat quick test. If fault did not occur below 4.25 volts, go to next step.
  28. Continuous Memory Code 31 and/or 35: EEC-IV Harness Check. Code 31 indicates an open in the EVP SIG or VREF, or a short to SIG RTN with engine at normal operating temperature and at idle. Code 35 indicates a short to VREF and/or VPWR, or an open in SIG RTN with engine at normal operating temperature and at idle. Enter KOEO CONTINUOUS MONITOR Mode. Observe VOM or test indicator for a fault indication while grasping harness close to sensor connector. Wiggle, shake and bend a small section of EEC-IV harness and work toward dash panel. Also check harness from dash panel to ECA. If a fault is indicated, isolate and repair or replace as necessary. Clear continuous memory and repeat quick test. If no fault is indicated, go to next step.
  29. Check ECA And Harness Connectors. Turn key off and wait 10 seconds. Disconnect 60-pin ECA connector. Check and repair pins and wiring if necessary. Clear continuous memory and repeat quick test. If connector, pin and wiring are okay, check for intermittent faults, clear continuous memory and check EGR valve diagnosis.
  30. Continuous Memory Code 33: Leak Test. Code 33 indicates EGR valve did not open with engine at normal operating temperature and with an EVR solenoid duty cycle present. Turn key off and wait 10 seconds. Disconnect vacuum hose at EGR valve and connect a vacuum pump to the vale. Apply 20 in. Hg to EGR valve. If EGR valve opens and holds vacuum, remove vacuum pump, reconnect EGR valve and go to next step. If EGR valve did not open or hold vacuum, remove pump, reconnect EGR valve. Clear continuous memory Code 33 and diagnosis EGR valve malfunction.
  31. EVR Check. Use Continuous Monitor Mode. Observe VOM or diagnostic tester for indication of a fault . Grasp harness close to EVR solenoid connector. Wiggle, shake and bend a small section of the harness, working toward ECA. Inspect connectors and terminals for obvious damage and repair as necessary. If any faults are indicated, isolate and repair. Clear Continuous Memory and repeat quick test. If no fault is indicated, fault cannot be duplicated at this time. Testing is complete.
  32. Continuous Memory Code 34: Check EVP Resistance While Applying Vacuum To EGR Valve. EVP circuit indicated that EGR valve was open with engine at normal operating temperature and at idle. Turn key off. Disconnect harness from EVP sensor. Disconnect vacuum hose at EGR valve an attach vacuum pump to EGR valve. Set DVOM on 200K-ohm scale. Measure resistance between EVP SIGNAL and VREF at the EVP sensor. Observe DVOM reading while increasing vacuum to 10 in. Hg. See Fig 1 . If resistance gradually changes from no more than 5500 ohms to no less than 100 ohms, remove vacuum pump and reconnect EGR valve. Clear Continuous Memory Code 34 and go to next step. If resistance did not change as specified, remove vacuum pump and reconnect EGR valve. Clear Continuous Memory Code 34. Check for EGR valve mechanical malfunction.
  33. 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 and replace if necessary. If filter is okay, replace EVR solenoid. Connect all vacuum hoses, clear Continuous Memory and repeat QUICK TEST. If Code 34 is not present, fault cannot be duplicated at this time. Testing is completed.
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