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Ivan
Ivan, ASE Certified Master Technician
Category: Car
Satisfied Customers: 4867
Experience:  ASE Master Tech w/ 20+ years in the field. Self employed for 9 years. Member of AUTOLAB radio show.
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Sierra 1500: CKP..changing..the crankshaft position sensor..chev

Resolved Question:

Do you have to do the CKP learn procedure after changing the crankshaft position sensor in a 2001 chev sierra 1500?
Submitted: 3 years ago.
Category: Car
Expert:  Ivan replied 3 years ago.

Ivan :

Hello and good evening. You will need a scan tool to enable the relearn mode. Here is the procedure once you get that far.

IMPORTANT: While the learn procedure is in progress, release the throttle immediately when the engine starts to decelerate. The engine control is returned to the operator and the engine responds to throttle position after the learn procedure is complete.

  1. Connect the scan tool.
  2. Apply the vehicles parking brake.
  3. Block the drive wheels.
  4. Close the vehicles hood.
  5. Place the vehicles transmission in Park (A/T) or Neutral (M/T).
  6. Idle the engine until the engine coolant temperature reaches 65°C (150°F) .
  7. Turn OFF all the accessories.
  8. Apply the brakes for the duration of the procedure.

IMPORTANT: If the crankshaft position (CKP) system variation learn procedure cannot be completed successfully, refer to DTC P1336 for additional diagnostic information.

  1. Use the scan tool in order to enable the CKP system variation learn procedure.
  2. Slowly accelerate the engine speed to 4,000 RPM .
  3. Immediately release the throttle when the engine speed decreases.
  4. Turn OFF the ignition for 15 seconds after the learn procedure is completed successfully.

Idle Learn Procedure
Anytime the powertrain control module (PCM) or the battery is disconnected, the PCM loses power, or the PCM is reprogrammed, the PCMs learned idle position is lost. The engine idle is unstable when the learned idle position is lost.

Perform the following procedure in order to return the learned idle to the correct position:

Automatic Transmission

  1. Turn OFF the ignition.
  2. Restore the PCM battery feed.
  3. Turn OFF the A/C controls.
  4. Set the parking brake and block the drive wheels.
  5. Start the engine.
  6. Ensure that the engine coolant temperature is more than 80°C (176°F) .
  7. Shift the transmission into Drive.
  8. Allow the engine to idle for 5 minutes .
  9. Shift the transmission into Park.
  10. Allow the engine to idle for 5 minutes .
  11. Turn OFF the engine for 30 seconds .

Manual Transmission

  1. Turn OFF the ignition.
  2. Restore the PCM battery feed.
  3. Turn OFF the A/C controls.
  4. Set the parking brake and block the drive wheels.
  5. Place the transmission in Neutral.
  6. Start the engine.
  7. Ensure that the engine coolant temperature is more than 80°C (176°F) .
  8. Allow the engine to idle for 5 minutes .
  9. Turn OFF the engine for 30 seconds .

Your JA Expert,

Ivan :

Ivan

Customer :

So the vehicle will not run correctly until this is done? And basically only the GM dealer has a scanner that does this procedure right?

Ivan :

Snap on Scanners will allow this procedure. I am sure most of the upper scale scanners like OTC will do it as well. It will not run to its optimum until it is completed and it will set a code in memory as well until its done.

Customer :

At first the truck ran extremely rough until it just wouldn't start. Bought scanner and had o2 codes as well as the crankshaft sensor. Replaced crankshaft sensor truck now starts but runs extremely rough and keeps stalling - won't idle. Assuming that is because of what u said above. Scanner is not getting the crankshaft code or any codes now, however have not ran the vehicle for more than a minute at most as it keeps stalling

Ivan :

You may have to use 2 feet to keep it running until this gets done. It is basically the procedure to sync the cam and crank sensors.

Ivan :

Also, Make sure you are not dealing with a dirty throttle plate as well. That can affect idle quality

Customer :

Guess we may have to find a scanner with this capability, since ours does not seem to have the relearn function. Thanks

Ivan :

You are welcome. Once you find one, it may take 2 or 3 times for the vehicle to accept the procedure, so just be patient

40635.8475253819
Ivan, ASE Certified Master Technician
Category: Car
Satisfied Customers: 4867
Experience: ASE Master Tech w/ 20+ years in the field. Self employed for 9 years. Member of AUTOLAB radio show.
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