Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

electronic spark timing question

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by rh88k5, Dec 22, 2002.

  1. rh88k5

    rh88k5 Registered Member

    Joined:
    Sep 11, 2002
    Posts:
    94
    Likes Received:
    0
    Location:
    Burlington, N.J.
    I've been getting a trouble code 42 lately, which points to the EST. I do not own a scanner and am not up on troubleshooting the computer controlled systems,can anybody steer me in the right direction as to what to check? '88 350 blazer /forums/images/graemlins/1zhelp.gif
     
  2. rh88k5

    rh88k5 Registered Member

    Joined:
    Sep 11, 2002
    Posts:
    94
    Likes Received:
    0
    Location:
    Burlington, N.J.
    Know that I've thought about it, do I even have EST? Did'nt that come in 1989?
     
  3. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

    Joined:
    Jan 21, 2001
    Posts:
    20,716
    Likes Received:
    2
    Location:
    Undisclosed Location
    Yes, you do. I believe EST is on all the computer controlled vehicles. I have it on my '87.
     
  4. manyblazers

    manyblazers Registered Member

    Joined:
    Dec 13, 2002
    Posts:
    33
    Likes Received:
    0
    Location:
    toronto, Canada
    Have you done any timing work recently? I may be wrong here but the last time I got that code it was because I had unplugged the brown/tan wire that goes to the computer to set the timing and forgot to replug it back together. On your truck it should be either next to the brake booster or by the heater core.
     
  5. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

    Joined:
    Jan 21, 2001
    Posts:
    20,716
    Likes Received:
    2
    Location:
    Undisclosed Location
    Nope, not recently, but yeah, you hit it on the head. Mine's near the brake booster.
     
  6. Thunder

    Thunder 3/4 ton status

    Joined:
    Jul 20, 2000
    Posts:
    8,946
    Likes Received:
    1
    Location:
    Northeast Nevada
    The magnetic pick up coil in the distributor going bad will give a code 42.The check engine will come on then go off after a while.
    Also there may be a slight miss when you are in high gear when going down the road if it is bad.

    Sometimes the dist module can throw a code 42 too.
    Check these two first before you go replacing expensive parts.
     
  7. rh88k5

    rh88k5 Registered Member

    Joined:
    Sep 11, 2002
    Posts:
    94
    Likes Received:
    0
    Location:
    Burlington, N.J.
    Both the pickup coil and dist. module were replaced in Sept. I've been thinking about putting the old module back in to see if it goes away. The miss at high speed sounds like what I have, but not just at high speed, sometimes on decelleration the light comes on (code 42) also.
     
  8. Thunder

    Thunder 3/4 ton status

    Joined:
    Jul 20, 2000
    Posts:
    8,946
    Likes Received:
    1
    Location:
    Northeast Nevada
    A code 42 is set by: the ECM applys bypass voltage to the dist module.
    This should change the timing. The ECM sees this and everything is ok
    If the timing does not change then it sets a code 42.
    I would check the old module out. Many auto parts stores will test then for free. Take them both down and have them checked.
    Check all the wires and connections too for breaks and corrosion.

    A short or open ground in the mag pickup coil or dist mod will set the code.
    Those are the only two parts that I know of that will set a 42
    There is a square box on a mount ( along with the EGR solonoid and MAP sensor, both these have vacume lines to them) on the passenger side of the Throttle body. It is the box without any vacume line to it.
    It is also part of the circut but its main function is to retard the timing when the knock sensor detects pinging. These are pretty much trouble free and usually that side of the timing circut sets code 43.
     
  9. R72K5

    R72K5 Banned

    Joined:
    Mar 5, 2001
    Posts:
    8,905
    Likes Received:
    0
    Location:
    central IL
    1980 was first year for ESC system
     

Share This Page