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PLEASE help me fix this!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by zcarczar, Aug 1, 2002.

  1. zcarczar

    zcarczar 1/2 ton status

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    Ok, i got a little problem with the ignition system on my 89, i keep getting a code 43 which is ESC bypass/failure. I dont really care about the check engine light or anything, but when it comes on my truck runs like a 305 and sucks gas. So far ive replaced the knock sensor twice, the knock sensor harness once, and the ESC from an 89 burban. Im going to try an ignition module this weekend. Anybody know whats wrong with it? If it helps i have access to a GM Tech 1, and i have the factory Fuel and Emmisions/Driveability manual for my truck.
    Thanks in advance.
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Whatever it is it is sending your motor into 'limp home' mode, basically the computer adjusts the fuel curve to full rich and retards the timing to prevent damage until the problem has been fixed.

    It could be a module...but I'm no GM tech by anyone's definition. Good luck!

    Rene
     
  3. Blue85

    Blue85 Troll Premium Member

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    I don't have any experience with this, but I would use the Tech 1 to look for counts of knock retard to see if the ESC is doing anything. Does this vehicle have a seperate ESC controller or does the knock sensor connect directly to the ECM? I don't see how it would see a problem with just the knock sensor, it would just never see knock, which is why I wonder if it's a seperate box. You might want to trace the wiring with an ohm meter.

    Is it possible that overall timing is just messed up and the ECM is getting confused? I think that you always set the distributor base timing to zero and let the ECM make all of the adjustments.

    Just a couple ideas
     
  4. zcarczar

    zcarczar 1/2 ton status

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    It does have the seperate ESC box, Im almost beginning to think that there is something wrong with the wiring or the ECM since whenever I drive with the Tech 1 to see if its getting a knock signal I wont get one, but as soon as I restart the car without the Tech 1 I will almost immediately get the check engine light on.
    The timing was the first thing that I checked and it is set at base timing. I also think that maybe some of the wires got fried because I did have to have some of the wire replaced because they melted together. I also tested to see if the sensor works by tapping on the block by the knock sensor, and I did get a signal from that.
    Thanks
     
  5. Blue85

    Blue85 Troll Premium Member

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    So just leave the Tech 1 connected at all times. /forums/images/icons/laugh.gif

    Sounds like you should look at the wiring from the ESC to the PCM, no?
     
  6. zcarczar

    zcarczar 1/2 ton status

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    I wish i could leave it connected all the time, but the dealership I work at uses it a lot. I think that the ESC i put in may have fixed it, I havent gotten a light since last night when i put it in. If this doesnt fix it im going after the ignition module and putting a GM one in it instead of the no name aftermarket one i have. Hopefully i wont have to deal with the wiring at all.
    Thanks
     
  7. Blue85

    Blue85 Troll Premium Member

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    </font><blockquote><font class="small">In reply to:</font><hr />
    im going after the ignition module and putting a GM one in it instead of the no name aftermarket one i have

    [/ QUOTE ]
    Maybe you have identified your problem?
     

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