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  1. #1

    Angry 1998 Chevrolet Silverado 5.7 Code p0340 code help

    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
    2007 Chevrolet Aveo 90K Miles

    1998 C1500 XCab 145K, Flowmaster Exhaust, Stock Engine, 4L60E trans, Amsoil thoughout.

  2. #2
    Jr. Engineer hundojoe's Avatar
    Join Date
    Feb 2010
    Elk River, Minnesota


    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 by hundojoe; 08-06-2010 at 11:38 AM.
    1999 Silverado Regular Cab Short Box
    Black on Black, Line-X sprayed in bed liner
    5.3 with K&N CAI, Texas Speed 220/220 cam with 112 deg LSA
    Texas Speed computer Tune
    American Racing Headers with Cats
    4.11 gears front and back, with Eaton rear posi
    Flowmaster 40series true duals
    16X8 American Racing Nitros with 305/70/16 Goodyear MTR's
    285's in the pic

    If it ain't broke...........Give me a minute!

    Im not completely useless, I can be used as a bad example...

  3. #3


    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. #4


    According to my wiring diagram (from Chiltons and downloaded free from the vehicle repair guides at, 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.
    '98 K1500 Suburban LS 5.7 L 4L60E NV246 ARB
    '92 Ford Explorer XLT 4x4 4.0 L A4LD BW13-54 Trac-loc rear
    "My toys were the greasy cogs and springs and pistons that lay around all over the place, and these, I can promise you, were far more fun to play with than most of the plastic rubbish children are given nowadays." Danny in Roald Dahl's Danny The Champion of the World

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