Silverado 2008

PCM Learn Procedure

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Specific to:

Chevrolet Silverado 1500 2008


NOTE
This procedure is performed after the PCM is flashed or replaced. Do not perform this procedure if DTC-s are set.


NOTE
Using the GM diagnostic scan tool, or equivalent, refer to the on-screen reprogramming directions and perform the PCM learn procedure.

  1. Start and idle the engine for three minutes.
  2.  
  3. Using the scan tool, monitor the desired idle speed and the actual idle speed.
  4.  
  5. The PCM will start to learn the new idle cells and the desired idle speed should start to decrease.
  6.  
  7. Turn the engine off for sixty seconds.
  8.  
  9. Start and idle the engine for three minutes.
  10.  
  11. After three minutes, the engine should be idling normally.
    NOTE
    During the drive cycle the check engine light may come on with the idle speed DTC-s. If idle speed codes are set, clear them so the PCM can continue to learn.


    NOTE
    If the idle speed has not been learned the vehicle will need to be driven at speeds above 44 miles per hour with several decelerations and extended idles.

  12.  
  13. After the drive cycle, the engine should be idling normally.
  14.  
  15. If the engine speed has not been learned, turn the engine off for sixty seconds. Repeat the above step.
  16.  
  17. Once the engine speed has returned to normal, clear the DTC-s.
  18.  

 
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