HE: Exhaust Gas Recirculation (EGR) Systems

HE: Introduction See: HE: Exhaust Gas Recirculation (EGR) Systems - Introduction

Continued from: See: HE1 - HE30

HE31 CHECK D.P.F. EGR SENSOR VOLTAGE WHILE EXERCISING EGR VALVE

• Key on, engine off.
• View DPFEGR PID and make note of voltage.
• Typical D.P.F. EGR sensor voltage with no EGR flow is between 0.2 and 1.3 volt.
• Disconnect vacuum hose at EGR valve and plug hose.
• Connect a hand vacuum pump to EGR valve.
• Start engine and bring to idle.
• Observe DPFEGR PID at idle and compare to the key on engine off voltage. (A higher voltage at idle could be due to a non-seating EGR valve.)
• Apply just enough vacuum to EGR valve to open it 7-10 kPa (2-3 in-Hg) without stalling engine and release vacuum. Repeat several times while observing DPFEGR PID. (DPFEGR PID voltage must increase as valve begins to open and return to initial value as vacuum is released. A slow to return voltage could be an indication of a binding or a slow-closing EGR valve.)

Does the DPFEGR PID voltage indicate an open, binding or slow-closing EGR valve?
Yes

• REMOVE and INSPECT the EGR valve for signs of contamination,

unusual wear, carbon deposits, binding and other damage. REPAIR as necessary.

No

• KEY OFF. GO to HE32

.

HE32 MONITOR EGR VALVE VACUUM WHILE WIGGLING EGRVR CIRCUIT

Note: An intermittent short to GND in the EGRVR circuit will cause the vacuum applied to the EGR valve to be higher than normal while the short is present. The vacuum available at the EGR valve at idle is normally below 3.4 kPa (1.0 in-Hg) and it takes about 5.4 kPa (1.6 in-Hg) for the valve to begin to open.

• Remove hand vacuum pump.
• Connect vacuum gauge to EGR valve vacuum hose.
• Key on, engine running.
• Observe vacuum gauge for an indication of a fault while performing the following:
• Lightly tap on the EGR vacuum regulator solenoid; wiggle the EGR vacuum regulator solenoid connector and vehicle harness between solenoid and PCM. A fault is indicated by a sudden jump in vacuum reading.

Is intermittent fault found?
Yes

• ISOLATE fault and REPAIR as necessary.

No

• RECONNECT vacuum hose. KEY OFF. GO to HE33

.

HE33 INSPECT EGR VACUUM REGULATOR SOLENOID AND VACUUM HOSES FOR POTENTIAL PLUGGING

• Remove EGR vacuum regulator solenoid vent filter and inspect for contamination and excessive water absorption. (In cold climate, excessive water in filter could freeze and plug the EGR vacuum regulator solenoid vent.)
• Inspect EGR vacuum hose for possible blockage or pinching.

Is EGR vacuum regulator solenoid vent or filter contaminated or vacuum hose plugged?
Yes

• REPAIR EGR vacuum regulator solenoid or EGR vacuum hose as necessary.

No

• Unable to duplicate or identify fault at this time. GO to Z1 See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 5: Pinpoint Tests\Z: Intermittent - Pinpoint Test

.

HE50 DTC P1405: INSPECT UPSTREAM PRESSURE HOSE CONNECTIONS

• Inspect upstream hose at D.P.F. EGR sensor and orifice tube assembly for disconnect or poor connection.

Is hose off or poorly connected?

• REPAIR as necessary. COMPLETE EGR Monitor Repair Verification

Drive Cycle (REFER to Section 2, Drive Cycles See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 2: Diagnostic Methods\Drive Cycles).

No

• GO to HE51

.

HE51 INSPECT UPSTREAM PRESSURE HOSE FOR PLUGGING

Note: It is essential that the D.P.F. EGR pressure hose used is the correct repair part and not a substitute.

• Visually inspect upstream pressure hose routing. Hose must not be pinched or have dips in it where water could settle or freeze.
• Remove upstream pressure hose and carefully inspect for plugging, water or leaks.

Is there a fault detected in the hose?
Yes

• REPAIR or REPLACE upstream pressure hose as necessary. COMPLETE

EGR Monitor Repair Verification Drive Cycle (REFER to Section 2, Drive Cycles See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 2: Diagnostic Methods\Drive Cycles).

No

• GO to HE52

.

HE52 CHECK ORIFICE TUBE ASSEMBLY AND D.P.F. EGR SENSOR

• Inspect the upstream connection on the D.P.F. EGR sensor for plugging or damage at the sensor.
• Inspect the exhaust manifold side pressure pickup tube at the orifice tube assembly for plugging or damage.

Is the D.P.F. EGR sensor or orifice tube assembly plugged or damaged?
Yes

• REPAIR or REPLACE D.P.F. EGR sensor or orifice tube assembly

as necessary. COMPLETE EGR Monitor Repair Verification Drive Cycle (REFER
to Section 2, Drive Cycles See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 2: Diagnostic Methods\Drive Cycles).

No

• GO to HE53

.

HE53 CHECK D.P.F. EGR SENSOR OUTPUT BY APPLYING VACUUM WITH HAND PUMP

• Disconnect pressure hoses at D.P.F. EGR sensor.
• Connect a hand vacuum pump to the downstream connection at sensor (intake manifold side of sensor or the smaller diameter pickup tube).
• Key on, engine off.
• Access DPFEGR PID and note PID value.
• Apply 27 to 30 kPa (8 to 9 in-Hg) vacuum to the D.P.F. EGR sensor and hold for a few seconds.
• Quickly release vacuum.
• The DPFEGR PID voltage must be between 0.2 and 1.3 volt with the key on and no vacuum applied.
• The DPFEGR PID voltage must increase to greater than 4.0 volts with the vacuum applied.
• The DPFEGR PID must drop to less than 1.5 volts in less than 3 seconds when vacuum is released.

Does the DPFEGR PID voltage indicate a fault in the D.P.F. EGR sensor?
Yes

• REPLACE D.P.F. EGR sensor. COMPLETE an EGR Monitor Repair Verification

Drive Cycle (REFER to Section 2, Drive Cycles See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 2: Diagnostic Methods\Drive Cycles).

No

• Unable to duplicate or identify fault at this time. GO to Z1 See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 5: Pinpoint Tests\Z: Intermittent - Pinpoint Test

.

HE60 DTC P1406: INSPECT DOWNSTREAM PRESSURE HOSE CONNECTIONS

Note: If the fault is currently present, DTC P1408 will be output in Key On Engine Running (KOER) Self-Test.

• Inspect downstream hose at D.P.F. EGR sensor and orifice tube assembly for disconnect or poor connection.

Is hose OFF or poorly connected?

• REPAIR as necessary.

No

• GO to HE61

.

HE61 INSPECT DOWNSTREAM PRESSURE HOSE FOR PLUGGING

Note: It is essential that the D.P.F. EGR sensor pressure hose is the correct repair part and not a substitute.

• Visually inspect downstream pressure hose routing. Hose must not be pinched or have dips in it where water can settle or freeze.
• Remove downstream pressure hose and carefully inspect for plugging, water or leaks.

Is there a fault detected in the hose?
Yes

• REPAIR or REPLACE as necessary.

No

• GO to HE62

.

HE62 CHECK ORIFICE TUBE ASSEMBLY AND D.P.F. EGR SENSOR

• Inspect the connections at the D.P.F. EGR sensor for plugging or damage.
• Inspect the intake manifold side pressure pickup tube and orifice tube assembly for plugging, loose connection or damage.

Is the D.P.F. EGR sensor or orifice tube assembly plugged, loose or damaged?
Yes

• REPAIR or REPLACE D.P.F. EGR sensor or orifice tube assembly

as necessary.

No

• GO to HE63

.

HE63 CHECK EGR SENSOR OUTPUT BY APPLYING VACUUM WITH HAND PUMP

• Disconnect pressure hoses at D.P.F. EGR sensor.
• Connect a hand vacuum pump to the downstream connection at sensor (intake manifold side of sensor or the smaller diameter pickup tube).
• Key on, engine off.
• Access DPFEGR PID and note PID value.
• Apply 27 to 30 kPa (8 to 9 in-Hg) vacuum to the D.P.F. EGR sensor and hold for a few seconds.
• Quickly release vacuum.
• The DPFEGR PID voltage must be between 0.2 and 1.3 volt with the key on and no vacuum applied.
• The DPFEGR PID voltage must increase to greater than 4.0 volts with the vacuum applied.
• The DPFEGR PID must drop to less than 1.5 volts in less than 3 seconds when vacuum is released.

Does the DPFEGR PID voltage indicate a fault in the D.P.F. EGR sensor?
Yes

• REPLACE D.P.F. EGR sensor.

No

• Unable to duplicate or identify fault at this time. GO to Z1 See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 5: Pinpoint Tests\Z: Intermittent - Pinpoint Test

.

HE70 DTC P0401: RUN KOER SELF-TEST

• Run KOER Self-Test.

Is KOER DTC P1408 output?
Yes

• Fault is currently present. GO to HE71

.

No

• GO to HE90

.

HE71 DTC P1408: RETRIEVE CONTINUOUS MEMORY DTCS

Note: If any DTC other than DTC P1406 is output, record DTC and refer to Diagnostic Trouble Code (DTC) Charts See: A L L Diagnostic Trouble Codes ( DTC )\Testing and Inspection\Diagnostic Trouble Code Descriptions in Section 4 after completing this Pinpoint Test.

• Retrieve all Continuous Memory DTCs.

Is DTC P1406 output?
Yes

• GO to HE60

.

No

• GO to HE72

.

HE72 RUN KOER SELF-TEST WHILE MONITORING EGR VACUUM

• Disconnect vacuum hose at EGR valve and connect hose to a vacuum gauge.

Note: Since the EGR vacuum hose is disconnected, ignore DTCs during this KOER Self-Test.

• Run Key On Engine Running (KOER) Self-Test while monitoring gauge. Approximately 30 seconds into test, EGR flow will be requested for a few seconds. The vacuum at this time should increase above 5.4 kPa (1.6 in-Hg) to open the valve.

Does the vacuum increase to 10 kPa (3.0 in-Hg) or greater at any time during KOER Self-Test?
Yes

• The vacuum indicated is sufficient to open the EGR valve. Fault

is unlikely to be in EGR vacuum control system. KEY OFF. GO to HE73
.

No

• The vacuum indicated is insufficient to open the EGR valve.

KEY OFF. GO to HE80
.

HE73 INSPECT D.P.F. EGR SENSOR PRESSURE HOSES

• Visually inspect both pressure hoses for reversed connection at D.P.F. EGR sensor or at orifice tube assembly.
• Inspect both hoses for improper routing. Hoses should not be pinched or have dips where water could settle or freeze.
• Inspect both hoses for leaks and blockage.
• Inspect D.P.F. EGR sensor and orifice tube assembly for blockage or damage at the pickup tubes.

Is a fault detected?

• REPAIR pressure hoses as necessary.

No

• GO to HE74

.

HE74 CHECK D.P.F. EGR SENSOR OUTPUT BY APPLYING VACUUM WITH HAND PUMP

• Disconnect pressure hoses at D.P.F. EGR sensor.
• Connect a hand vacuum pump to the downstream connection at sensor (intake manifold side of sensor or the smaller diameter pickup tube.)
• Key on, engine off.
• Access DPFEGR PID and note PID value.
• Apply 27-30 kPa (8-9 in-Hg) vacuum to the D.P.F. EGR sensor and hold for a few seconds.
• Quickly release vacuum.
• The DPFEGR PID voltage must be between 0.2 and 1.3 volt with the key on and no vacuum applied.
• The DPFEGR PID voltage must increase to greater than 4.0 volts with the vacuum applied.
• The DPFEGR PID must drop to less than 1.5 volts in less than 3 seconds when vacuum is released.

Does the DPFEGR PID voltage indicate a fault in the D.P.F. EGR sensor?
Yes

• REPLACE D.P.F. EGR sensor.

No

• RECONNECT pressure hoses. GO to HE76

.

HE76 CHECK EGR VALVE FUNCTION BY APPLYING VACUUM WITH HAND PUMP

• Disconnect vacuum hose at EGR valve and plug hose.
• Connect a hand vacuum pump to EGR valve.
• Start engine and bring to idle.
• Access DPFEGR and rpm PIDs.
• Slowly apply 27 to 34 kPa (8 to 10 in-Hg) of vacuum to the EGR valve and hold it for 10 seconds. If engine wants to stall, increase rpm with throttle to maintain a minimum of 1000 rpm.
• Look for the following:
• EGR valve starts opening at about 5.4 kPa (1.6 in-Hg) vacuum indicated by increasing DPFEGR PID voltage.
• DPFEGR PID voltage increasing until EGR valve is fully open. DPFEGR PID must read 2.5 volts minimum with full vacuum applied.
• DPFEGR PID voltage steady when vacuum is held. If voltage drops within a few seconds, the EGR valve or vacuum source can be leaking.

Does the DPFEGR PID voltage indicate that the EGR valve is operating as described in this test?
Yes

• GO to HE85

.

No

• REMOVE and INSPECT the EGR valve for signs of contamination,

unusual wear, carbon deposits, binding, leaking diaphragm and other damage.
If EGR valve is OK, look for an obstructed EGR port in the intake manifold
or plugged orifice tube assembly. REPAIR as necessary.

HE80 CHECK VACUUM SOURCE AND VACUUM HOSES TO AND FROM EGR VACUUM REGULATOR SOLENOID

• Inspect vacuum lines between vacuum source and EGR vacuum regulator solenoid and between EGR vacuum regulator solenoid and EGR valve for leaks, kinks, disconnects, blockage, routing or any damage.
• Disconnect vacuum hoses at EGR vacuum regulator solenoid.
• Connect EGR vacuum regulator solenoid vacuum source hose to a vacuum gauge.
• With engine warm and at idle, take vacuum gauge reading.

Is the vacuum gauge reading a minimum of 51 kPa (15 in-Hg) at idle and vacuum lines OK?
Yes

• KEY OFF. GO to HE81

.

No

• ISOLATE fault and REPAIR as necessary.

HE81 CHECK VPWR VOLTAGE TO EGR VACUUM REGULATOR SOLENOID

• Disconnect EGR vacuum regulator solenoid.
• Key on, engine off.
• Measure VPWR circuit voltage at EGR vacuum regulator solenoid harness connector.

Is EGR vacuum regulator solenoid VPWR voltage greater than 10.5 volts?
Yes

• KEY OFF. GO to HE82

.

No

• REPAIR open circuit.

HE82 CHECK EGR VACUUM REGULATOR SOLENOID RESISTANCE

• Measure EGR vacuum regulator solenoid resistance.

Is solenoid resistance between 26 and 40 ohms?
Yes

• GO to HE83

.

No

• REPLACE EGR vacuum regulator solenoid.

HE83 CHECK EGRVR CIRCUIT FOR SHORT TO PWR IN HARNESS

Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

• Disconnect PCM.
• Key on, engine off.
• Measure voltage between EGRVR circuit at the PCM harness connector and battery negative post.

Is voltage greater than 1.0 volt?
Yes

• REPAIR short circuit.

No

• KEY OFF. GO to HE84

.

HE84 CHECK EGRVR CIRCUIT FOR OPEN IN HARNESS

• Measure resistance of EGRVR circuit between PCM harness connector pin and EGR vacuum regulator solenoid harness connector.

Is resistance less than 5.0 ohms?
Yes

• RECONNECT PCM and EGR vacuum regulator solenoid. GO to HE85

.

No

• REPAIR open in EGRVR circuit.

HE85 CHECK EGR VACUUM REGULATOR SOLENOID VACUUM OUTPUT CAPABILITY BY GROUNDING EGRVR CIRCUIT

• Disconnect vacuum hose at the EGR valve and connect to a vacuum gauge.
• Key on, engine running.
• With engine at idle, jumper PCM EGRVR circuit to chassis ground.

Is vacuum gauge reading 13.5 kPa (4.0 in-Hg) or greater?
Yes

• REPLACE PCM (refer to section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) See: Programming and Relearning\Flash Electrically Eraseable Programmable Read Only Memory - Flash EEPROM).

No

• REPLACE EGR vacuum regulator solenoid.

HE90 INSPECT EGR SYSTEM FOR AN INTERMITTENT FAILURE

• Visually inspect the EGR system for signs of intermittent failure.

Is a fault found?
Yes

• REPAIR fault as necessary.

No

• GO to HE91

.

HE91 INSPECT D.P.F. EGR SENSOR PRESSURE HOSES

• Visually inspect both pressure hoses for reversed connection at D.P.F. EGR sensor or at orifice tube assembly.
• Inspect both hoses for improper routing. Hoses should not be pinched or have dips where water could settle or freeze.
• Inspect both hoses for leaks and blockage.
• Inspect D.P.F. EGR sensor and orifice tube assembly for blockage or damage at the pickup tubes.

Is a fault detected?

• REPAIR pressure hoses as necessary.

No

• GO to HE92

.

HE92 CHECK D.P.F. EGR SENSOR OUTPUT BY APPLYING VACUUM WITH HAND PUMP

• Disconnect pressure hoses at D.P.F. EGR sensor.
• Connect a hand vacuum pump to the downstream connection at sensor (intake manifold side of sensor or the smaller diameter pickup tube.)
• Key on, engine off.
• Access DPFEGR PID and note PID value.
• Apply 27-30 kPa (8-9 in-Hg) vacuum to the D.P.F. EGR sensor and hold for a few seconds.
• Quickly release vacuum.
• The DPFEGR PID voltage must be between 0.2 and 1.3 volt with the key on and no vacuum applied.
• The DPFEGR PID voltage must increase to greater than 4.0 volts with the vacuum applied.
• The DPFEGR PID must drop to less than 1.5 volts in less than 3 seconds when vacuum is released.

Does the DPFEGR PID voltage indicate a fault in the D.P.F. EGR sensor?
Yes

• REPLACE D.P.F. EGR sensor.

No

• RECONNECT pressure hoses. GO to HE93

.

HE93 CHECK EGR VALVE FUNCTION BY APPLYING VACUUM WITH HAND PUMP

• Disconnect vacuum hose at EGR valve and plug hose.
• Connect a hand vacuum pump to EGR valve.
• Start engine and bring to idle.
• Access DPFEGR and RPM PIDs.
• Slowly apply 17 to 34 kPa (5 to 10 in-Hg) of vacuum to the EGR valve and hold it for 10 seconds. If engine wants to stall, increase rpm with throttle to maintain a minimum of 800 rpm.
• Look for the following:
• EGR valve starts opening at about 5.4 kPa (1.6 in-Hg) vacuum indicated by increasing DPFEGR PID voltage.
• DPFEGR PID voltage increasing until EGR valve is fully open. DPFEGR PID should read 2.5 volts minimum with full vacuum applied.
• DPFEGR PID voltage steady when vacuum is held. If voltage drops within a few seconds, the EGR valve or vacuum source could be leaking.

Does the DPFEGR PID voltage indicate that the EGR valve is operating as described in this test?
Yes

• GO to HE94

.

No

• REMOVE and INSPECT the EGR valve for signs of contamination,

unusual wear, carbon deposits, binding, leaking diaphragm and other damage.
If EGR valve is OK, look for an obstructed EGR port in the intake manifold.
REPAIR as necessary.

HE94 INSPECT EGR VACUUM SIGNAL SUPPLY FOR INTERMITTENT FAILURE

• Disconnect plugged hose at EGR valve and connect to a vacuum gauge.
• Key on, engine running.
• Connect a jumper wire between EGRVR circuit and ground to activate the solenoid to full on. At idle, the vacuum gauge should read above 13.5 kPa (4.0 in-Hg).
• Observe vacuum gauge for an indication of a fault while performing the following:
• Lightly tap on the EGR vacuum regulator solenoid and wiggle the EGR vacuum regulator solenoid connector, vacuum lines and vehicle harness between the solenoid and PCM. A fault is indicated by a sudden drop in vacuum reading.

Is a fault indicated?
Yes

• ISOLATE fault and REPAIR as necessary.

No

• Unable to duplicate or identify fault at this time. (In cold

climates, the EGR valve may temporarily freeze shut and thaw when the engine
warms up causing the intermittent DTC.) GO to Z1 See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 5: Pinpoint Tests\Z: Intermittent - Pinpoint Test
.

HE100 EGR DIAGNOSIS BY SYMPTOM: CHECK FOR EGR FLOW WITH EGR VACUUM HOSE DISCONNECTED AND PLUGGED

Note: Perform KOER Self-Test and repair any DTCs before proceeding with this test.
The symptom charts have indicated possible EGR flow at idle with no EGR diagnostic trouble codes output.
Possible causes:

• EGR valve not fully seating.
• EGR vacuum regulator solenoid vent restricted.
• Damaged EGR vacuum regulator solenoid.
• Disconnect vacuum hose at EGR valve and plug hose.
• Key on, engine off.
• Access DPFEGR PID and note voltage.
• Start engine and bring to idle.
• With engine at idle, look at the DPFEGR PID voltage and compare to the engine off reading. An increase in the voltage at idle indicates that the differential pressure feedback EGR sensor is sensing EGR flow.

Is the DPFEGR PID voltage greater at idle by a minimum of 0.15 volt than with the engine off?
Yes

• The DPFEGR PID voltage is indicating EGR flow at idle. Since

the EGR vacuum hose is disconnected and plugged, the fault is most likely
in the EGR valve. REMOVE and INSPECT the EGR valve for signs of contamination,
unusual wear, carbon deposits, binding and other damage. REPAIR as necessary.

No

• This indicates a fault in the EGR valve vacuum supply. INSPECT

the EGR vacuum regulator solenoid vent and vent filter for restrictions. REPAIR
as necessary. If OK, REPLACE EGR vacuum regulator solenoid.

HE110 DTC P1409: CHECK EGR VACUUM REGULATOR SOLENOID RESISTANCE

• Disconnect EGR vacuum regulator solenoid.
• Measure EGR vacuum regulator solenoid resistance.

Is solenoid resistance between 26 and 40 ohms?
Yes

• GO to HE111

.

No

• REPLACE EGR vacuum regulator solenoid.

HE111 CHECK VPWR VOLTAGE TO EGR VACUUM REGULATOR SOLENOID

• Key on, engine off.
• Measure VPWR circuit voltage at EGR vacuum regulator solenoid harness connector.

Is voltage greater than 10.5 volts?
Yes

• KEY OFF. GO to HE112

.

No

• REPAIR open in VPWR circuit.

HE112 CHECK EGRVR CIRCUIT FOR OPEN IN HARNESS

Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

• Disconnect PCM.
• Measure resistance of EGRVR circuit between PCM Pin and EGR vacuum regulator solenoid harness connector.

Is resistance less than 5.0 ohms?
Yes

• GO to HE113

.

No

• REPAIR open in EGRVR circuit.

HE113 CHECK EGRVR CIRCUIT FOR SHORT TO POWER IN HARNESS

• Key on, engine off.
• Measure voltage between EGRVR at the PCM harness connector and battery negative post.

Is voltage less than 1.0 volt?
Yes

• KEY OFF. GO to HE114

.

No

• REPAIR short circuit.

HE114 CHECK EGRVR CIRCUIT FOR SHORT TO GROUND IN HARNESS

• Measure resistance between EGRVR and PWR GND circuits at the PCM harness connector.

Is each resistance greater than 10,000 ohms?
Yes

• REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) See: Programming and Relearning\Flash Electrically Eraseable Programmable Read Only Memory - Flash EEPROM).

No

• REPAIR short circuit.

HE120 CONTINUOUS MEMORY DTC P1409: WIGGLE EGR VACUUM REGULATOR SOLENOID WHILE MONITORING VPWR

Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.
Note: If DTC P1409 was output in Key On Engine Off (KOEO) or Key On Engine Running (KOER) Self-Test, GO to HE110 to diagnose present fault.

• Disconnect PCM.
• Key on.
• Measure voltage between EGRVR and PWR GND circuits at the PCM harness connector.
• Voltage must read greater than 10.5 volts. For an indication of a fault, look for this voltage to drop while performing the following:
• Lightly tap on the EGR vacuum regulator solenoid.
• Wiggle the EGR vacuum regulator solenoid connector.
• Grasp the EGR vacuum regulator solenoid harness connector and wiggle wires between solenoid and PCM.

Is a fault indicated?
Yes

• ISOLATE fault and REPAIR as necessary.

No

• Unable to duplicate or identify fault at this time. GO to Z1 See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 5: Pinpoint Tests\Z: Intermittent - Pinpoint Test

.