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Engine code 42

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by KILLERK5, Sep 3, 2002.

  1. KILLERK5

    KILLERK5 1/2 ton status

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    Alright I have been dealing with this for a while now. I have been getting a code 42. I had the dist. module tested and replaced. Now the light doesn't come on as often, but it still comes on. How hard is a pick coil to replace? I don't even know what one looks like. Is there anything else that could be causing a code 42?

    Thanks once again, I dont know what I would do without you guys' help!!
     
  2. zcarczar

    zcarczar 1/2 ton status

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    FYI, Code 42 Electronic Spark Timing Failure or Bypass. I had this one my car when my headers fried a bunch of wires. It was acompanied with Code 43 which is Electronic Spark Control Failure.
     
  3. Kyle89K5

    Kyle89K5 1/2 ton status

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    I'll try and help, but my truck is kinda toast right now too with the same problems. First thing, go pick up a Haynes AND a Chiltons manual, they both do a pretty good job of helping and explaining the problem.

    The EST system includes the knock sensor, so you may want to look at replacing that. If the EST system is not sending the proper voltage signals back to the ECM or the system is grounded, then you will get a code 42. The EST system is set up to retard the spark timing as much as 20 deg during knock conditions. Check the wiring going to the knock sensor. It runs awful close to the exhaust and starter and may have gotten a little scorched and be grounding itself every now and again.

    The one thing that I have found that is your BEST BET is to take the truck to a shop with an honest to goodness diagnostic machine, not a code reader. This will determine EXACTLY what is wrong and keep you from blindly chasing things like I've been doing for the last 3 weeks.
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    Gets expensive throwing parts at a problem doesn't it : ) If you guys keep your eyes open, you can pick up an OBD1 scanner (like my autoxray 240) for less than $150 from Ebay and various other places.

    Already saved a fair amount of money on my friends Ford Ranger. (although you still have to guess with Fords EEC-IV system, as there is apparently no live data stream, or the 240 can't "see" it) Showed both bad MAF and O2, replacing the O2 alone fixed everything. The MAF alone would have cost more than my scanner probably.
     
  5. Kyle89K5

    Kyle89K5 1/2 ton status

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    If only I could call you a liar to make myself feel better. /forums/images/icons/frown.gif

    You got it right. I'm in the process of making my own scanner /forums/images/icons/laugh.gif Found some really interesting software and sites here in the last couple of days, looking to snag something and use my laptop to help things out. I was able to drive my truck today, but not well. Still running rich. I'm pretty much at a loss.
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    winALDL looks like fun. If only I could get deals on laptops like I can on used truck parts... /forums/images/icons/smile.gif

    Once you get a scanner (or winALDL, just a lot more data with winALDL) running though, you will see the voltage the O2 sensor is putting out, knock count, all that good stuff. And the routine stuff too, but it makes everything else asy too! RPM, Alt output, baro pressure, vehicle speed (I think) etc. And thats just with the scanner!

    Eventually I'll probably try it out, but I think I'll worry about making one of my vehicles actually run and NEED it first : )
     
  7. Kyle89K5

    Kyle89K5 1/2 ton status

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    I'm sitting here right now trying to figure out how to wire up a cable to run winaldl. Got it downloaded. We'll see how it goes.

    BTW, my laptop was a birthday present /forums/images/icons/laugh.gif
     
  8. zcarczar

    zcarczar 1/2 ton status

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    Let us know how this works, i gotta couple laptops sittin around at my house.
     
  9. Thunder

    Thunder 3/4 ton status

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    Getting back to the subjet. I think you may be on the right track in replacing the pickup coil. When they go bad they will throw a intermitint code 42. usually comes on after it warms up. The engine may seem to stumble when in high gear.
    To replace it you have to pull the distributor.
    remove the drive gear and pull out the shaft.
    The pickup coil is the thing in the middle of the dist that looks like a doughnut.
    if you have a ohm meeter you can test the pickup coil to see if it is bad before you remove it.
    Hook the ohm meeter between the white and green leads on the wires that come off the coil and go to the module.. resistance should be between 500 and 1500 ohms. anything out of that range and the coil is bad.
     
  10. Kyle89K5

    Kyle89K5 1/2 ton status

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    I tell ya, other than making the cable, which cost me a total of about $5 in resistors and Transistors, THIS PROGRAM ROCKS!!!! It's a little tricky to get the wires into the ALDL, but once they are there, you're getting TONS of information. TONS!!!!
     
  11. zcarczar

    zcarczar 1/2 ton status

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    Well how did ya do it?
     
  12. dremu

    dremu Officious Thread Derailer Premium Member

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    Another observation ... I know nothing of this personally, as my TBI truck has been well-behaved since I bought it and I've only had troubles with my older Blazers ;-)

    I remember reading a thread on Usenet recently about a guy with a hot engine (ie hopped up, fancy cam etc) who got all kinds of ESC codes because his base timing was off for his engine. He had it right on for factory, but with his powerplant he ended up advancing it a coupla degrees and lo and behold, all went away.

    I can dig up the thread, or look on Google Groups for "Doc" and "ESC Code 42", oughta come up with something.

    Point being that, depending on your engine, you might just need to tweak the base timing. I guess the computer is supposed to adjust it for you, but I think it has a limited adjustment range.

    -- A
     
  13. Kyle89K5

    Kyle89K5 1/2 ton status

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    I downloaded WinALDL then used the diagram on their site to make my own cable. I had to buy a new solder gun so my grand cash outlay has been less than $25. The hardest part has been keeping the wires in the ALDL plug while I drive. Other than that, the software just sits there and logs info CONSTANTLY including speed and RPM. Kinda nice, I was able to check my speed against the Speedo to see how far off I was. Looks like the voltage on my O2 sensor is out of wack, so I've got to look into that this weekend.

    WinALDL ROCKS!!!!!!!!!!!
    It is a TON cheaper than a scanner (if you have a laptop or access to one) and gets a TON of information. Also, the only limit to how much data you log is dependent on the harddrive space you have left. I went to this site Custom EFIS to get the software. He also has the cables premade for about $30 if you don't want to do the work yourself.
     
  14. zcarczar

    zcarczar 1/2 ton status

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    Where did you get the parts to make the connector? I was looking at Radioshack.com and i couldnt find the transistor that is needed. Also, what ECM mode did you set youirs up to use? It seems like the 10 Ohm ALDL mode would be the one to get. One more thing do you have the actual name of the parts you got? It would be Extremly helpful if you could pass on the info. Thanks in Advance
     

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