Check engine light won't go off

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  #1  
Old 09-30-13, 11:27 AM
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Post Check engine light won't go off

I have a 2000 chevelot malibu and my car wont pass emission because it say's it's the knock sensor. My husband put a new knock sensor and a new fuel filter and the check engine light is still on. Plus the code still say's it's the knock sensor. Doe's anyone know what else it could be please help i need my car to pass so i can get my tag's
 
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  #2  
Old 09-30-13, 04:43 PM
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3.1(J)engine?what code?p0325?p0326?p0327?do you have a dc voltmeter?able to do voltage measurements?how many miles on car?mechanically sound engine?
 
  #3  
Old 09-30-13, 05:31 PM
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It's a 3.1 engine .The code is p0327 yes we have a dc volltmeter.yes. It has 199176 miles on it.yes
tried grounding the sensor. left it disconnected from the block and it still show that code
 
  #4  
Old 09-30-13, 06:54 PM
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Code P0327- The Knock sensor signal noise is above the expected average voltage 95% of a test cycle.
Enabling conditions: Engine running time was over 30 seconds. Coolant temperature was over 140 F.
Throttle angle was over 15%, indicating off idle operation with engine load over 45%. Engine speed was
between 1000 and 5000 RPM. The noise channel is a function of the PCM that calculates the average noise
in the knock signal, during a test period the signal was above the average calculated limit for 95% of the
test. No VSS, TPS or ECT codes present. Blocking conditions: None. Testing: Check for a noise source
such as alternator bearings, water pumps and other devices that could generate a false knock signal. Check
the voltage for the knock sensor while it is connected.backprobe connector.positive meter to wire and neg meter probe to battery negative terminal. The voltage should be 2.5 volts without spark knock. If the voltage is
wrong disconnect the sensor and measure the voltage with disconnected harness side.The voltage is 5 volts on the circuit back to the
PCM.positive meter to signal wire and neg meter probe to battery negative terminal.let me know results.
 
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Old 09-30-13, 07:16 PM
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Ok Thank's I'll Let You Know What He Find's.
 
  #6  
Old 10-01-13, 04:41 AM
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Did you try to clear the code? Some code readers do not let you clear the code. Most codes will clear on their own if the problem is fixed after 40 to 50 engine runs.
 
  #7  
Old 10-06-13, 10:18 AM
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got no voltage check the wire to pcm got continuity so wire checks out fine
 
  #8  
Old 10-08-13, 05:57 AM
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Signal Circuit Check;
Check for 4.6 to 5.0 volts on the signal circuit with the sensor disconnected, use battery negative as ground
reference.
If signal circuit voltage is low, check for a short to ground or poor contact at the PCM connector.
are you sure the negative meter had good ground at battery negative terminal?....test this by touching meter positive probe to battery positive terminal and see if meter reads battery voltage.with no voltage on wire at connector and no voltage at pcm.....check for a short to ground.....disconect pcm connector and with knock sensor connector disconnected take a digital ohmmeter and touch neg meter to negative battery terminal and positive to the knock sensor signal wire at pcm.....should read ol in the highest mega ohms setting.........if reading is low there is a short to ground.check pcm contact......if no short to ground and pcm contact is good and pcm is not putting out voltage would have to check for pcm power and grounds before replacing the pcm.....pcm would have to be flashed.......if you are unsure of your testing results with meter connections i would take to a reputable shop before replacing pcm....they are not cheap and have to be flashed.
 
  #9  
Old 10-08-13, 06:05 AM
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also wanted to add......make sure testing right wire at pcm.....pcm has 2 80 pin connectors....the knock sensor signal wire is pcm connector c1 pin 33 db wire.if you need the pin layout let me know and i can email it to you.
when you stated no voltage on wire.....was it with connector connected or disconnected?with connected you have to backprobe connector or use a piercing probe to get voltage reading and also have a good meter ground.
 
  #10  
Old 10-08-13, 12:36 PM
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yes can you email me the pin layout please i will let you know what happens my email is [email protected]
 

Last edited by the_tow_guy; 10-08-13 at 01:52 PM.
  #11  
Old 10-08-13, 04:10 PM
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He did bank 1 33 or 25 dark blue wire. checked connunity from lead connector to pin made sure itwas right wire.it shorted to ground
 
  #12  
Old 10-09-13, 05:54 PM
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Did you have the codes erased after replacement? Often times the codes have to be cleared before the light will go off. Try unhooking neg bat cable overnight. Sometime computer will reset itself with no power for so long
 
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Old 10-10-13, 05:40 AM
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trace wire and repair the wire that is shorted to ground.
 
  #14  
Old 10-11-13, 02:00 PM
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My check engine had been on for 2 years could not communicate with it (OBD1 scanner or jumper). A few days ago I purchased a ECM and PROM. I replaced the ECM and PROM... CEL was still on... however I could get codes (code 51, Bad PROM). I sent the PROM back to Cardone and got a replacement, Installed yesterday CEL went out. However my engine is really running rough and i'm not getting any codes (except 12)...
 
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