HE: Exhaust Gas Recirculation (EGR) Systems

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

HE1 DTC P1400: DETERMINE PRESENT DPFEGR PID VOLTAGE

• Key on, engine off.
• Access DPFEGR PID.

Is DPFEGR PID voltage less than 0.2 volt?
Yes

• Fault is currently present. KEY OFF. GO to HE2

.

No

• Fault is intermittent. GO to HE5

.

HE2 ATTEMPT TO INDUCE OPPOSITE D.P.F. EGR SENSOR VOLTAGE

• Disconnect D.P.F. EGR sensor.
• Key on, engine off.

Is DPFEGR PID value between 4.0 and 6.0 volts?
Yes

• REPLACE D.P.F. EGR sensor.

No

• GO to HE3

.

HE3 CHECK VREF AND SIG RTN CIRCUITS FOR OPEN IN HARNESS TO D.P.F. EGR SENSOR

• Measure voltage between VREF and SIG RTN circuits at the D.P.F. EGR sensor harness connector.

Is VREF voltage between 4.0 and 6.0 volts?
Yes

• KEY OFF. GO to HE4

.

No

• GO to C1 See: C: Reference Voltage - Pinpoint Test

.

HE4 CHECK DPFEGR CIRCUIT FOR SHORT TO GROUND AND SIG RTN IN HARNESS

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

• Disconnect scan tool from DLC.
• Disconnect PCM.
• Measure resistance between DPFEGR and SIG. RTN circuits at the PCM harness connector.
• Measure resistance between DPFEGR circuit at the PCM harness connector and battery negative post.

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.

HE5 PERFORM WIGGLE TEST ON D.P.F. EGR SENSOR AND CIRCUIT WHILE MONITORING DPFEGR PID FOR A SUDDEN CHANGE

• While monitoring DPFEGR PID, tap on the D.P.F. EGR sensor and wiggle the wiring while looking for a sudden change in value as an indication of an intermittent.

Is intermittent fault found?
Yes

• 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

.

HE10 DTC P1401: DETERMINE PRESENT DPFEGR PID VOLTAGE

• Key on, engine off.
• Access DPFEGR PID with a scan tool.

Is DPFEGR PID voltage greater than 4.0 volts?
Yes

• Fault is currently present. KEY OFF. GO to HE11

.

No

• Fault is intermittent. GO to HE19

.

HE11 CHECK DPFEGR CIRCUIT FOR SHORT TO PWR

• Disconnect D.P.F. EGR sensor.
• Key on, engine off.
• Measure voltage between DPFEGR circuit at the D.P.F. EGR sensor harness connector and chassis ground.

Is voltage greater than 10.5 volts?
Yes

• KEY OFF. GO to HE12

.

No

• GO to HE13

.

HE12 CHECK DPFEGR 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 DPFEGR circuit at the PCM harness connector and the battery negative post.

Is voltage greater than 10.5 volts?
Yes

• REPAIR short circuit.

No

• REPLACE damaged PCM.

HE13 INDUCE OPPOSITE D.P.F. EGR SENSOR VOLTAGE

• Connect a jumper wire between DPFEGR and SIG RTN circuits at the D.P.F. EGR sensor harness connector.

-
Note: If a scan tool communication concern exists, key off, remove jumper immediately and GO to HE18.

• Access DPFEGR PID.

Is DPFEGR PID voltage less than 0.05 volt?
Yes

• REMOVE jumper. GO to HE14

.

No

• Unable to induce opposite signal. KEY OFF. GO to HE16

.

HE14 CHECK VREF VOLTAGE TO D.P.F. EGR SENSOR

• Measure voltage between VREF and SIG RTN circuits at the D.P.F. EGR sensor harness connector.

Is VREF voltage between 4.0 and 6.0 volts?
Yes

• GO to HE15

.

No

• GO to C1 See: C: Reference Voltage - Pinpoint Test

.

HE15 CHECK DPFEGR CIRCUIT FOR SHORT TO VREF IN HARNESS

• Disconnect PCM.
• Measure resistance between DPFEGR and VREF circuits at the PCM harness connector. (For LS6/LS8 measure to both VREF pins.)

Is resistance greater than 10 K ohms?
Yes

• REPLACE D.P.F. EGR sensor.

No

• REPAIR short circuit.

HE16 CHECK DPFEGR CIRCUIT FOR OPEN IN HARNESS

• Disconnect PCM.
• Measure resistance of DPFEGR circuit between PCM harness connector pin and D.P.F. EGR sensor harness connector.

Is resistance less than 5.0 ohms?
Yes

• GO to HE17

.

No

• REPAIR open circuit.

HE17 CHECK SIG RTN CIRCUIT FOR OPEN IN HARNESS

• Measure resistance of SIG RTN circuit between PCM harness connector pin and D.P.F. EGR sensor harness connector.

Is resistance less than 5.0 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 open circuit.

HE18 CHECK DPFEGR CIRCUIT FOR SHORT TO VREF IN HARNESS

• Disconnect PCM.
• Measure resistance between DPFEGR and VREF circuits at the PCM harness connector. (For LS6/LS8 measure to both VREF pins.)

Is 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.

HE19 COMPLETE A WIGGLE TEST ON D.P.F. EGR SENSOR AND CIRCUIT WHILE MONITORING DPFEGR PID FOR A SUDDEN CHANGE

• While monitoring DPFEGR PID, tap on the D.P.F. EGR sensor and wiggle the wiring while looking for a sudden change in value as an indication of an intermittent.

Is intermittent fault found?
Yes

• 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

.

HE20 DTC P0402: CHECK FOR EGR FLOW AT IDLE WITH EGR VACUUM HOSE DISCONNECTED

Note: If DTC P1405 is in continuous memory, diagnose that first starting with HE50.

• Disconnect vacuum hose at EGR valve and plug hose.
• Run Key On Engine Running (KOER) Self-Test.

Is KOER DTC P0402 output or unable to run KOER Self-Test due to engine stall or no start?
Yes

• KEY OFF. INSPECT pressure hoses first for pinching and icing.

If OK, REMOVE and INSPECT the EGR valve and EGR tube for signs of contamination,
unusual wear, carbon deposits, binding and other damage. REPAIR as necessary.

No

• RECONNECT vacuum hose to EGR valve. GO to HE21

.

HE21 CHECK FOR EGR FLOW AT IDLE WITH EGR VACUUM HOSE CONNECTED

• EGR vacuum hose connected.
• Run KOER Self-Test.

Is KOER DTC P0402 output or unable to run KOER Self-Test due to engine stall or no start?
Yes

• There is possible EGR flow at idle. GO to HE22

.

No

• Fault is intermittent. INSPECT pressure hoses for pinching and

icing. REPAIR as necessary. If OK, GO to HE30
.

HE22 CHECK EGR SYSTEM VACUUM HOSES FOR INTEGRITY AND CONNECTION

Note: A pinched or plugged EGR vacuum hose can trap vacuum between the EGR vacuum regulator solenoid and EGR valve not allowing the EGR valve to close.

• Trace each vacuum hose from EGR vacuum regulator solenoid and verify that each hose is connected correctly. (Refer to vehicle vacuum diagram label.)
• Verify that the EGR valve vacuum hose is not pinched or plugged and routed properly.

Are vacuum hoses OK?
Yes

• RECONNECT vacuum hoses. GO to HE23

.

No

• REPAIR vacuum hoses as necessary.

HE23 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.

No

• RECONNECT D.P.F. EGR sensor. GO to HE24

.

HE24 CHECK FOR EGR FLOW AT IDLE WITH EGR VACUUM REGULATOR SOLENOID CONNECTOR OFF

• Disconnect vacuum hose at EGR valve and connect hose to vacuum gauge.
• Start engine and bring to an idle.
• While monitoring vacuum gauge, disconnect the EGR vacuum regulator solenoid harness connector.
• The EGR valve requires vacuum greater than 5.4 kPa (1.6 in-Hg) to begin to open. If the vacuum reading remains greater than 5.4 kPa (1.6 in-Hg) after the EGR vacuum regulator solenoid is electrically disconnected, this would indicate a mechanical fault in the EGR vacuum regulator solenoid.

Does the EGR vacuum remain greater than 5.4 kPa (1.6 in-Hg) at idle even after EGR vacuum regulator solenoid is electrically disconnected?
Yes

• This indicates a fault in the EGR vacuum regulator solenoid.

KEY OFF. GO to HE25
.

No

• KEY OFF. GO to HE26

.

HE25 INSPECT EGR VACUUM REGULATOR SOLENOID VENT FOR PLUGGING

Note: A plugged EGR vacuum regulator solenoid vent will not allow EGR vacuum to vent to atmosphere.

• Disconnect EGR vacuum regulator solenoid vacuum hoses.
• Remove EGR vacuum regulator solenoid vent cap (if removable).
• Remove filter and inspect for blockage or icing in some cases.
• With the EGR vacuum supply port plugged, apply 34 to 51 kPa (10 to 15 in-Hg) of vacuum directly to EGR vacuum regulator solenoid vacuum source port with a hand vacuum pump. If the vacuum holds or is slow to release to atmosphere, the EGR vacuum regulator solenoid vent could be plugged or restricted.

• REPAIR EGR vacuum regulator solenoid as necessary. If unable

to repair, REPLACE EGR vacuum regulator solenoid.

No

• REPLACE EGR vacuum regulator solenoid.

HE26 MEASURE EGR VACUUM REGULATOR SOLENOID COIL RESISTANCE

• Measure resistance across EGR vacuum regulator solenoid.

Is resistance between 26 and 40 ohms?
Yes

• GO to HE27

.

No

• REPLACE EGR vacuum regulator solenoid.

HE27 CHECK EGRVR CIRCUIT FOR SHORT TO GROUND IN HARNESS

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

• Disconnect scan tool from DLC.
• Disconnect PCM.
• Measure resistance between EGRVR circuit at the PCM harness connector and battery negative post.

Is resistance greater than 10,000 ohms?
Yes

• GO to HE28

.

No

• REPAIR short circuit.

HE28 CHECK EGRVR CIRCUIT FOR SHORT TO VREF

• Measure resistance between EGRVR and VREF circuits at the PCM harness connector. (For LS6/LS8 measure to both VREF pins.)

Is 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.

HE30 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.

No

• RECONNECT D.P.F. EGR sensor. GO to HE31.

Continued: See: HE31 - HE120