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Home >> Ford >> 1996 >> Aerostar Van Window >> Repair and Diagnosis >> External Pages >> Different car >> Section 121 (Engine Controls - Tests W/Codes - EEC-IV (4.0L)) >> Circuit Tests >> Circuit Test DN - EVP Sensor & EVR Solenoid >> Diagnostic Aids

Diagnostic Aids

WARNING: This page is about a different car, the 1995 Ford Explorer and 1995 Ford Aerostar. However, it is still accessible from the selected car via links, so may be relevant.

EVR solenoid receives variable input from PCM, which allows it to control vacuum level to EGR valve. Vacuum not used by EGR is routed to EVR solenoid and vented to atmosphere.

Perform this test when instructed by QUICK TEST or if directed by other test procedures. To prevent replacement of good components, be aware a damaged EGR valve may be cause of problem. This CIRCUIT TEST is intended to diagnose the following:

Fig 1: EVP Sensor & EVR Solenoid Connector Terminal ID (4.0L)
G93H40524
TEST PIN NO. 26 (VREF) WIRE COLOR IDENTIFICATION

Application Wire Color
All Models Brown/White
TEST PIN NO. 27 (EVP) WIRE COLOR IDENTIFICATION

Application Wire Color
All Models Brown/Light Green
TEST PIN NO. 33 (EVR) WIRE COLOR IDENTIFICATION

Application Wire Color
All Models Brown/Pink
TEST PIN NO. 46 (SIG RTN) WIRE COLOR IDENTIFICATION

Application Wire Color
All Models Gray/Red
NOTE: EVR sensor is preloaded when attached to EGR valve. Valve failure causing EVR sensor to lose preload may set Code 327.

1) Code 327: Generate Code 337  Code 327 indicates EVP sensor signal is less than self-test minimum of 0.2 volt. Possible causes for this fault are:

Turn ignition off. Disconnect EVP wiring harness connector at sensor. Install a jumper wire between VREF terminal and EVP terminal at EVP sensor wiring harness connector. Repeat KOEO SELF-TEST and KOER SELF-TEST. Check for Code 337. Ignore all other codes at this time. If Code 337 is present, replace EVP sensor and repeat QUICK TEST. If Code 337 is not present, remove jumper wire and go to next step. If no codes are present, remove jumper wire and go to step 4).

2) Check VREF Circuit Voltage  Disconnect EVP sensor. Turn ignition on. Measure voltage between VREF terminal and SIG RTN terminal at EVP sensor wiring harness connector. If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, go to CIRCUIT TEST C.

3) Check EVP Circuit Resistance  Turn ignition off. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between EVP terminal at EVP sensor wiring harness connector and test pin No. 27. If resistance is 5 ohms or more, repair open circuit and repeat QUICK TEST. If reading is less than 5 ohms, go to next step.

4) Check EVP Circuit For Short To Ground  Ensure ignition is off and EVP sensor is disconnected. Measure resistance between test pin No. 27 and test pins No. 40, 46 and 60. If any reading is less than 10,000 ohms, repair short circuit and repeat QUICK TEST. If all readings are 10,000 ohms or more, replace PCM and repeat QUICK TEST.

5) Code 337: Generate Code 327  Code 337 indicates EVP sensor signal is greater than self-test maximum of 4.81 volts. Possible causes for this fault are:

Turn ignition off. Disconnect EVP sensor. Perform KOEO SELF-TEST and KOER SELF-TEST. Check for Code 327. Ignore all other codes at this time. If Code 327 is present, go to next step. If Code 327 is not present, go to step 7).

6) Check VREF Circuit Voltage  Turn ignition on. Measure voltage between VREF terminal and SIG RTN terminal at EVP sensor wiring harness connector. If reading is 4-6 volts, replace EVP sensor. Repeat QUICK TEST. If reading is not 4-6 volts, go to CIRCUIT TEST C.

7) Check EVP Circuit For Short To Power  Turn ignition off. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 27 and test pins No. 26 and 57 at breakout box. 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 PCM and repeat QUICK TEST.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 7) to step 10). No test procedures have been omitted.

10) Code 558: Check EVR Solenoid Resistance  Code 558 indicates fault in EVR solenoid circuit. Possible causes for this fault are:

Turn ignition off. Disconnect EVR solenoid connector. Measure resistance across EVR solenoid terminals. If reading is not 20-70 ohms, replace EVR solenoid assembly and repeat QUICK TEST. If reading is 20-70 ohms, go to next step.

11) Check VPWR Circuit Voltage  Disconnect EVR solenoid. Turn ignition on. Measure voltage between negative battery terminal and VPWR terminal at EVR solenoid wiring harness connector. If reading is less than 10.5 volts, repair open VPWR circuit and repeat QUICK TEST. If reading is 10.5 volts or more, go to next step.

12) Check EVR Circuit Continuity  Turn ignition off. Disconnect EVR solenoid. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between EVR terminal at EVR solenoid wiring harness connector and test pin No. 33. If reading is less than 5 ohms, go to next step. If reading is 5 ohms or more, repair open circuit and repeat QUICK TEST.

13) Check EVR Circuit For Short To Power Or Ground  Measure resistance between test pin No. 33 and pins No. 37, 40, 46, 57 and 60 at breakout box with ignition off. If any reading is less than 10,000 ohms, repair short circuit and repeat QUICK TEST. If code is repeated, replace EVR solenoid. If all readings are 10,000 ohms or more, replace PCM. Remove breakout box, and repeat QUICK TEST.

NOTE: A break in step numbering sequence occurs at this point.Procedure skips from step 13) to step 20). No test procedures have been omitted.

20) Code 334: Check For Code 558  Code 334 indicates EGR valve and/or EVP is not fully seated in closed position. EVP voltage signal, in closed position, is greater than self-test maximum of 0.67 volt. Because of EVP sensor preload, determining whether EGR valve is seated or EVP sensor contacts EGR valve stem is difficult. Possible causes for this fault are:

Perform KOEO SELF-TEST. If Code 558 is present, return to step 10). If Code 558 is not present, go to next step.

21) Perform SELF-TEST Without EGR  Remove and plug vacuum line to EGR valve. Perform KOEO SELF-TEST and KOER SELF-TEST. If Code 334 is still present, go to next step. If Code 334 is not present, check EVR solenoid for obstructions. If no obstructions are present, replace EVR solenoid.

22) Check EGR Valve & EVP Sensor Operation  Turn ignition off. Disconnect EVP sensor. Inspect harness and connector, and service if necessary. Remove and plug vacuum hose to EGR valve. Install vacuum gauge at EGR valve vacuum hose. Operate EGR valve by applying and releasing vacuum. Install vacuum hose to EGR valve and wiring harness connector to EVP sensor. Repeat KOEO SELF-TEST and KOER SELF-TEST. If Code 334 is present, go to next step. If Code 334 is not present, original fault was caused by poor continuity at EVP sensor connector or binding/sticking of EGR valve stem.

23) Check EVP Signal Voltage  Turn ignition off. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Turn ignition on. Measure voltage between test pin No. 27 and test pin No. 46 at breakout box. If voltage is less than 0.67 volt, replace PCM and repeat QUICK TEST. If voltage is greater than 0.67 volt, go to next step.

24) EGR Valve/EVP Sensor Fault Isolation  Remove EGR valve and EVP sensor. Inspect valve and sensor for binding, carbon deposits, excessive wear and damage. Repair or replace as necessary. Install EGR valve and EVP sensor. Perform KOEO SELF-TEST and KOER SELF-TEST. If Code 334 is still present, replace EGR valve. If Code 334 is not present, testing is complete.

25) Service Code 328  Service Code 328 indicates EVP sensor is lower than normal (0.24 volt) in closed position. Possible causes for this fault are:

Turn ignition off. Disconnect EVP sensor wiring harness connector. Inspect harness and connector, and service as necessary. Remove EGR valve vacuum hose. Attach vacuum pump to EGR valve. Operate EGR valve by applying and releasing vacuum. Install vacuum hose to EGR valve and wiring harness connector to EVP sensor. Repeat KOEO SELF-TEST and KOER SELF-TEST. If Code 328 is not present, original fault was caused by poor continuity at EVP sensor connector or binding/sticking of EGR valve stem. If Code 328 is present, go to next step.

26) Check EVP Signal Voltage  Turn ignition off. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Remove and plug EGR valve vacuum hose. Connect vacuum pump to EGR valve vacuum hose. Turn ignition on. Measure voltage between test pin No. 27 and test pin No. 46 at breakout box while performing following: apply 6 in. Hg to EGR valve and slowly bleed vacuum completely off. If voltage does not drop to less than 0.24 volt, replace PCM and repeat QUICK TEST. If voltage drops to less than 0.24 volt, go to next step.

27) Substitute EVP Sensor On Original EGR Valve  Turn ignition off. Install a known-good EVP sensor on original EGR valve. Ensure all hoses and electrical connectors are attached. Perform KOEO SELF-TEST and KOER SELF-TEST. If Code 328 is present, check EGR valve for mechanical malfunction. If Code 328 is not present, replace original EVP sensor. Repeat QUICK TEST.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 27) to step 40). No test procedures have been omitted.

40) KOER Code 332: Check Vacuum At EGR  KOER Code 332 indicates EVP sensor input did not change after PCM signaled operation of EGR. Possible causes for this fault are:

Turn ignition off. Disconnect vacuum hose from EGR valve. Connect a vacuum gauge at open end of hose. Perform KOER SELF-TEST while observing vacuum gauge. If vacuum reading is more than one in. Hg, remove vacuum gauge and go to step 43). If reading is one in. Hg or less, go to next step.

41) Verify Vacuum Supply To EVR Solenoid  Turn ignition off. Disconnect EVR solenoid vacuum hose. Install vacuum gauge at vacuum hose. Start engine and check vacuum. If reading is 10 in. Hg or more, go to next step. If reading is less than 10 in. Hg, check vacuum line to EVR solenoid. Repair if necessary. Repeat QUICK TEST.

42) Check Vacuum Between EVR Solenoid & EGR Valve  Check vacuum hose for cracks, loose connections, blockage and kinks. Repair or replace vacuum hose if necessary, 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. After repairs are made, repeat QUICK TEST.

43) Check EVP Sensor & EGR Valve Operation  Turn ignition off. Disconnect EVP sensor. Inspect connector and harness for damage, and service as necessary. Remove vacuum hose from EGR valve. Connect vacuum pump to EGR valve. Operate EGR valve operation by applying and releasing vacuum. Connect vacuum line to EGR valve. Connect wiring harness connector to EVP sensor. Repeat KOER SELF-TEST. If Code 332 is still present, go to next step. If Code 332 is not present, original code was set either by poor continuity at EVP sensor connector or sticking EGR valve. Test is complete.

44) Verify EGR Valve Vacuum Control  Turn ignition off. Install tachometer. Remove Idle Air Control (IAC) wiring harness connector. Remove and plug vacuum hose from EGR valve. Start engine, and allow it to idle with transmission in Neutral. Ensure idle speed is adjusted correctly. Connect vacuum pump to EGR valve. Slowly apply 5-10 in. Hg. If engine idle decreases more than 100 RPM with vacuum applied and returns to correct idle with vacuum released, replace EVP sensor. Repeat QUICK TEST. If vacuum does not drop more than 100 RPM with vacuum applied, repair or replace EGR valve. Repeat QUICK TEST.

NOTE: A break in step numbering sequence occurs at this point.Procedure skips from step 44) to step 90). No test procedures have been omitted.

90) Continuous Memory Code 327, 328 Or 337  Continuous Memory Code 327 or 328 indicates EGR valve closed further than normal or EVP circuit failed with intermittent low voltage sometime during engine operation. Code 337 indicates EVP signal to PCM was above maximum self-test limit sometime during engine operation. Possible causes for these faults are:

Turn ignition off, and wait 10 seconds. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Turn ignition on. Connect DVOM between test pins No. 27 and 46 at breakout box. Wiggle wiring harness and lightly tap on EVP sensor. If voltage remains steady at .24-.67 volt, go to next step. If voltage is erratic or not within .24-.67 volt range, remove and inspect EVP sensor wiring harness connector. Repair or replace if necessary. Repeat QUICK TEST. If sensor connector is okay, replace EVP sensor. Repeat QUICK TEST.

91) Check Wiring Harness  Turn ignition off. Connect DVOM between test pins No. 27 and 46 at breakout box. Observe DVOM for fault indication while wiggling and bending small sections of wiring harness near sensor, working from sensor toward dash panel. Wiggle and bend wiring harness from firewall to PCM. If fault is indicated, isolate fault and repair wiring harness. Clear codes, and repeat QUICK TEST. If fault is not found, go to next step.

92) Measure EVP Signal Voltage While Exercising EVP Sensor  Remove and plug vacuum hose to EGR valve. Install vacuum gauge at EGR valve vacuum hose. Turn ignition on. Measure voltage between test pins No. 27 and 46 at breakout box while performing following: apply 5-10 in. Hg to EGR valve and slowly bleed off vacuum completely. If voltage steadily fluctuates between 0.24-4.81 volts, problem is intermittent and cannot be duplicated at this time. If voltage does not fluctuate between 0.24-4.81 volts, replace EVP sensor and repeat QUICK TEST.

NOTE: A break in step numbering sequence occurs at this point.Procedure skips from step 92) to step 110). No test procedures have been omitted.

110) Continuous Memory Code 332  Code 332 indicates EGR valve did not open with engine at normal operating temperature and with EVR solenoid signal present sometime during engine operation. Possible causes of this fault are:

Turn ignition off. Disconnect vacuum hose at EGR valve. Connect vacuum pump to valve. Apply 10-20 in. Hg to EGR valve. If EGR valve opens and holds vacuum, go to next step. If EGR valve does not open and hold vacuum, service or replace EGR valve as necessary and repeat QUICK TEST.

111) EVR Solenoid & Wiring Harness Check  Turn ignition off. Disconnect vacuum hose from EGR valve. Connect EGR valve hose to vacuum gauge. Disconnect PCM 60-pin connector and inspect it for damaged terminals. Repair or replace as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box.

112)  Start engine and allow it to idle. Connect jumper wire between test pins No. 33 and 40. Tap on EVR sensor and wiggle wiring harness while observing vacuum gauge. If vacuum gauge shows a sudden drop in vacuum, isolate cause and repair as necessary. Repeat QUICK TEST. If vacuum gauge does not show a drop in vacuum, problem is intermittent and cannot be duplicated at this time.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 112) to step 115). No test procedures have been omitted.

115) Continuous Memory Code 334  Code 334 indicates EGR valve was open with engine idling at normal operating temperature. Possible causes for this fault are:

Turn ignition off. Disconnect vacuum hose from EGR valve. Connect EGR valve hose to vacuum gauge. Start engine, and allow it to idle. Tap EVR sensor and wiggle wiring harness while observing vacuum gauge. If vacuum gauge reading does not remain less than one in. Hg and/or has sudden vacuum increase, service or replace EVR solenoid. If vacuum gauge reading remains less than one in. Hg with no sudden increase, go to next step.

116) EVR Solenoid Check  Leave engine idling and vacuum gauge connected to EGR valve hose. Observe vacuum gauge while wiggling and bending small sections of wiring harness near EVR sensor, working from sensor toward dash panel. Wiggle and bend wiring harness from firewall to PCM. If vacuum gauge shows an increase in vacuum, isolate cause and repair as necessary. If vacuum gauge does not show an increase in vacuum, go to next step.

117) Check EVR Signal At PCM  Turn ignition off. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Start engine, and allow it to idle. Connect DVOM between test pins No. 27 and 46 at breakout box. Wiggle wiring harness and lightly tap EVP sensor. If voltage is 0.67 volt or less, problem is intermittent and cannot be duplicated at this time. If voltage increases to more than 0.67 volt, remove and service EGR valve. If voltage is still more than 0.67 volt, replace EVP sensor. Repeat QUICK TEST. Testing is complete.

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