Mechanics

WHAT TO CHECK NEXT?

1997 Chevrolet Lumina • 157,000 miles

3.1L/Automatic. Car had been running okay, cooling fans only worked when (new)coolant temp sensor was disconnected, and also the car delayed re-engaging gears after slowing down or downshifting. Trans works fine if downshifting manually. Anyways, I was getting off the highway and the car stalled; Started fine, and stalled again when slowing down close to a stop, then started again. Did the same thing again, but would not start. The next day it started rough, and I drove it home a few blocks. Now the car won't start. Checked fuel/spark and both seem good to me. Spark side gapped. Had code for TCC solenoid, but I cleared it and have not drove it to the point it would reset. Has p1406 pintle potions circuit. Pintle works good and voltage changes when pushing it with a screwdriver. The pintle voltage should be.9 volts when closed and 4.5 when open, mine shows 2.5v closed and 4.5 open. Resistance for EGR valve solenoid is good. Carbon build up in plenum that Ive cleaned the best I can(still a little dirty). Wont start with EGR valve off engine. I checked compression on two cylinders and it was at 30lbs, but not sure if I check it correctly. Car had been driving hot for a short period of time. Recently replaced water pump and a/c compressor.

Any suggestion will help.

Thank you!
Avatar
JohnNC
December 30, 2011.



ENGINE CONTROLS - TESTS W/CODES - 3.1L ENGINE -1997 Chevrolet Lumina
Page 1 of 3
DTC P1406 - EGR VALVE PINTLE POSITION CIRCUIT

NOTE: For circuit reference, see the appropriate WIRING DIAGRAMS article. For
connector and terminal identification, see CONNECTOR
IDENTIFICATION.
Circuit Description

Powertrain Control Module (PCM) monitors EGR valve pintle position. If PCM detects a pintle position signal voltage that is out of normal range, or a signal voltage that is not acceptable for proper EGR
system operation, DTC P1406 will set.
Conditions for setting DTC: ? EGR feedback is less than 0.14 volt at any time.
? EGR feedback is 0.4 volt greater or less than the EGR closed valve pintle position when desired EGR position is commanded to zero percent.
? Actual EGR position is 10 percent greater or less than the desired EGR position. ? Any of the above conditions present for longer than 20 seconds.
Diagnostic Procedures

Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the BASIC TESTING 3.1L article. After performing OBD system check, go to next step.
Start engine and allow it to idle. Using scan tool, select EGR data list. Observe EGR ACTUAL POS display. If reading is zero percent, go to next step. If reading is not zero percent, go to step
11).
Turn ignition off. Turn ignition on, with engine off. Using scan tool, select MISC TESTS. Select EGR CONTROL function. Command EGR valve open from 10-100 percent positions while
comparing EGR DESIRED POS to EGR ACTUAL POS. If EGR DESIRED POS remain close to EGR ACTUAL POS at all commanded positions, go to next step. If EGR DESIRED POS does
not remain close to EGR ACTUAL POS at all commanded positions, go to step 6).
Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Using a test light connected to ground, probe EGR ignition filter circuit at PCM harness connector. If test light
illuminates, go to next step. If test light does not illuminate, go to step 32).
Turn ignition off. Reconnect PCM harness connector. Turn ignition on. Using scan tool, review and record scan tool FAIL RECORDS data. Operate vehicle within the FAIL RECORDS
conditions as noted. Using scan tool, monitor SPECIFIC DTC INFO for DTC P1406 until the DTC test runs. If scan tool indicates that DTC P1406 failed this ignition, go to step 22). If scan
tool does not indicate that DTC P1406 failed this ignition, see DIAGNOSTIC AIDS. Disconnect EGR valve harness connector. Connect DVOM between ignition feed circuit and
control circuit terminals at EGR valve harness connector. Observe scan tool and command EGR valve commanded to 100 percent position. If voltage reading is near battery voltage, go to step
17). If voltage reading is not near battery voltage, go to next step.
With test light connected to ground, probe EGR valve ignition feed circuit terminal at harness connector. If test light illuminates, go to step 9). If test light does not illuminate, go to next step.

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12/30/2011
ENGINE CONTROLS - TESTS W/CODES - 3.1L ENGINE -1997 Chevrolet Lumina
Page 2 of 3
8.
Remove and inspect fuse for EGR valve ignition feed circuit. If fuse is blown, locate and repair short to ground in ignition feed circuit. Replace fuse. After repairs, go to step 33). If fuse is okay,
go to step 24).
Turn ignition off. Disconnect PCM harness connector. Check for an open in EGR control circuit. Repair as necessary. After repairs, go to step 33). If circuit is okay, go to next step.
Check EGR control circuit for poor terminal connection at PCM connector. Repair as necessary. After repairs, go to step 33). If connection is okay, go to step 30).
Disconnect EGR valve harness connector. Using scan tool, observe EGR ACTUAL POS display. If reading is zero percent, go to step 13). If reading is not zero percent, go to next step.
Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Check voltage between ground and EGR pintle position circuit terminal at PCM connector. If voltage is about zero volts,
to step 31). If voltage is not about zero volts, go to step 26).
With test light connected to battery voltage, probe sensor ground circuit terminal at EGR valve harness connector. If test light illuminates, go to step 15). If test light does not illuminate, go to
next step.
Check sensor ground circuit for poor terminal connection at PCM. Repair as necessary. If terminal connection is okay, check for an open in sensor ground circuit between PCM and EGR valve
connector. Repair as necessary. After repairs, go to step 33). If connection is okay, go to step 31). With test light connected to battery voltage, probe control circuit at EGR valve terminal harness
connector. If test light illuminates, go step 16). If test light does not illuminate, go to step 22). Turn ignition off. Disconnect PCM harness connector. Turn ignition on. With test light connected
to battery voltage, probe EGR control circuit terminal at PCM harness connector. If test light illuminates, go to step 28). If test light does not illuminate, go to step 30).
Connect DVOM between sensor ground circuit and 5-volt reference circuit terminals at EGR valve harness connector. If voltage is 5 volts, go to next step. If voltage is not 5 volts, go to step
23).
With test light connected to battery voltage, probe EGR pintle position circuit terminal at EGR valve harness connector. If test light illuminates, go to step 21). If test light is off, go to next step.
Connect a jumper wire between 5-volt reference "A" circuit and pintle position circuit terminals at EGR valve harness connector. Using scan tool, observe EGR ACTUAL POS display. If reading is
100 percent, go to step 22). If reading is not 100 percent, go to next step.
Turn ignition off. Disconnect PCM harness connector. Check pintle position circuit for an open circuit or poor terminal connection at PCM connector. Repair as necessary. After repairs, go to
step 33). If circuit is okay, go to step 31).
21. Turn ignition off. Disconnect PCM connector. With test light connected to battery voltage, probe pintle position circuit terminal at PCM connector. If test light illuminates, go to step 29). If test
light does not illuminate, go to step 30).
22. Check for poor terminal connections at EGR valve harness connector. Repair as necessary. After repairs, go to step 33). If connections are okay, go to step 27).
23. Check for an open or short to ground in 5-volt reference "A" circuit. Repair as necessary. After repairs, go to step 33). If circuit is okay, go to step 25).
Locate and repair open in ignition feed circuit. After repairs, go to step 33).
Check EGR 5-volt reference "A" circuit for poor terminal connection at PCM. Repair as necessary. After repairs, go to step 33). If connection is okay, go to step 31).
Locate and repair short to voltag
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24. 25.
E in EGR pintle
position circuit. After repairs,
g
o to step 33).
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ENGINE CONTROLS - TESTS W/CODES - 3.1L ENGINE -1997 Chevrolet Lumina
Page 3 of 3
27. 28.
29.
Replace EGR valve. After replacing EGR valve, go to step 33).
Locate and repair short to ground in EGR control circuit. After repairs, go to step 33).
Locate and repair short to ground in EGR pintle position circuit. After repair is completed, go to step 31).
Check EGR pintle position circuit or EGR control circuit for short to sensor ground circuit. Repair as necessary. After repairs, go to step 33). If circuit is okay, go to step 31).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 33).
Locate and repair open in EGR ignition filter circuit to PCM. After repairs, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to
with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions
recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1406 until DTC P1406 test runs. If scan tool indicates FAILED THIS IGN, repeat step 3). If scan tool does
not indicate FAILED THIS IGN, repair is complete.
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32. 33.
Clear DTCs. Turn ignition on,
Diagnostic Aids

Check for deposits that may interfere with EGR valve pintle extending completely or cause pintle to stick. Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An
intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help
determine how often condition that caused DTC to be set occurs.

Checking engine compression: Remove spark plug. Thread compression tester hose into plug opening completely. Make sure it is tight by hand (no wrench needed). Make sure O-ring is good. Crank engine for 5-10 seconds.
Compression should be at least 100PSI. Maximum variance of 20%. My book says 30%, but that's too much.

Rivermikerat
Dec 30, 2011.