1998 Chevrolet Silverado 5.7 Code p0340 code help

Discussion in 'GM Powertrain' started by campuscop2003, Aug 5, 2010.

  1. campuscop2003

    campuscop2003 New Member

    I started my truck today after having the battery disconnected for 3 day and got a CEL for P0102 and Camshaft position sensor circuit malfunction code. I checked all the wiring and it looks good can't find any issue. I also replace the camshaft position sensor to be safe. Cleared the codes, and boom. P0340 is right back. The truck is running find. It was missing badly prior to the sensor change but now runs great. I can't figure out why its still throwing that code. And to make matters worse next month my emissions inspection is due, and I'm flat broke. Please help. Thanks
  2. hundojoe

    hundojoe Rockstar 100 Posts

    This may sound strange but your alternator might be causing the problem, if the voltage regulator is going bad the stray voltage will cause weird $hit to happen to the computer.
    Last edited: Aug 6, 2010
  3. campuscop2003

    campuscop2003 New Member

    I found the 20 amp fuse labeled engine 1 blows as soon as the key is turned on. There is no voltage on the 12 v supply to both the cam sensor or maf. Are they on this fuse??
  4. MrShorty

    MrShorty Epic Member 5+ Years 1000 Posts

    According to my wiring diagram (from Chiltons and downloaded free from the vehicle repair guides at autozone.com), those are both powered by a 20 A fuse called ENG-1, along with the O2 sensor heaters and the CANP solenoid. I would suggest you get a wiring diagram, and then it's time to find the short.

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