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Got a code reader for x-mas and need help deciphering readings

Discussion in 'The Garage' started by afroman006, Dec 27, 2003.

  1. afroman006

    afroman006 1/2 ton status

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    Mom got me a code reader for x-mas and I hooked it up to the burb this morning and got 3 codes. While I have a general idea of what they mean and what to do I need a little help. The codes are as follows, word for word from the scanner.

    Code 39: Torque Converter clutch (TCC) is off
    Code 43: Elec Spark control (ESC) module or sensor problem
    Code 68: Overdrive ratio error eng RPM above input speed (I think this is related to the Code 39)

    When I first started it up the idle speed was 1200 RPM! but it dropped down to 850 after a few minutes...

    The 02 sensor reading kept flashing back and forth between lean rich lean rich lean rich I dont know if that means its normal or something's wrong?
    And finally it said my spark advance was 18* This sounded a little high to me but I'm not sure.
    These were the only readings that I knew what they were or caught my eye but I figure these are a good place to start.

    Thx for the help my new scanner is tite!
     
  2. btolenti

    btolenti 1/2 ton status

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    May I ask what code reader you got? I am looking to get one too.
     
  3. HarryH3

    HarryH3 1 ton status Author

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    [ QUOTE ]
    Code 39: Torque Converter clutch (TCC) is off
    Code 43: Elec Spark control (ESC) module or sensor problem
    Code 68: Overdrive ratio error eng RPM above input speed (I think this is related to the Code 39)

    [/ QUOTE ]
    Do you ever feel the torque converter cluth engage? If not, then that is the source of 39 and 68. Code 43 can be a bad knock sensor, bad ESC module, or a bad connection in the circuit. A failed ignition module can also cause this error, as the ESC circuitry is separate from the part of the module that generates the spark. A factory service manual is VERY useful for tracking this one down.

    [ QUOTE ]
    When I first started it up the idle speed was 1200 RPM! but it dropped down to 850 after a few minutes...

    [/ QUOTE ]
    This is normal if the engine is started in cold weather.

    [ QUOTE ]
    The 02 sensor reading kept flashing back and forth between lean rich lean rich lean rich I dont know if that means its normal or something's wrong?

    [/ QUOTE ]
    That's exactly what it is supposed to do.

    [ QUOTE ]
    And finally it said my spark advance was 18* This sounded a little high to me but I'm not sure.

    [/ QUOTE ]
    That number may be skewed by the Code 43 error. I'm pretty sure that would cause the timing to go into a limp-home mode, using a non-ESC-corrected timing map. Does that number change as you drive? In normal operation it will be constantly changing as RPM, load, throttle, etc. change.
     
  4. afroman006

    afroman006 1/2 ton status

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    The scanner is an Actron. Its badass /forums/images/graemlins/thumb.gif It can scan any GM, Chrysler, or Ford car or truck (not sure of years but I think its ALOT). How does the TC clutch engaging feel? If its not engaging I assume that means I need a new one? If it makes any difference it seems to run well when the engine is cold but it sporadicaly starts running horribly once warm. I'm going to replace the whole distributor as I think its bushings are worn out but I'm thinkin there's something going on with the TC/tranny too. 200k miles original tranny and I assume TC. Thx for the help.
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    You can force lockup in the OBD1 system by shorting the pin for TCC (ALDL pinout available free online in about a million places) to ground with a paperclip. Dunno what the min/max speed/gear is for your year vehicle, but 35MPH+ cruise conditions would likely be ideal.

    Easiest though is to have someone watch RPM on the scanner while you are in 3rd or 4th gear. Cruising, anything over about 35MPH should do. Constant throttle, no acceleration, keep gas pedal in same position, and LIGHTLY tap the brake pedal. (just enough to get brake lights to light, not to decrease engine speed) Engine RPM should jump (climb) by a fair amount (I think up to about 500RPM, depends on the converter etc.) then shortly drop down by the same amount as constant throttle/vehicle speed with no brake apply is continued.
     
  6. HarryH3

    HarryH3 1 ton status Author

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    If you pay close attention while taking off somewhat gently from a standing start you'll feel the tranny shift 3 times, then you should fell a 4th, smaller "shift" as the torque converter locks up. Mine drop the RPM about 250 RPM when it happens.
     
  7. Thunder

    Thunder 3/4 ton status

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    18 degrees is about right if you are idling with the engine warm. Its right about where mine runs( 16-18 degrees at idle).

    The code 43 is usually the knock sensor or related circut as said above. Fixing it may also clear the other codes. I am not sure. But if I rember right. If the timing is not with in specs for a certain rpm the TC wont lock. Possibly throwing the other codes.
    Repair the code 43 first. Then worry about the TC lock up issues.
     
  8. dyeager535

    dyeager535 1 ton status Premium Member

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    Scanner should be telling you knock count as well. May or may not help, but you should be seeing SOME knock counts, and some timing retard as the knock sensor detects it.

    From the "good old days" (GM manual from the 80's) you are supposed to be able to check the knock sensor for operation by hitting an exhaust manifold with a hammer and watching the timing.
     
  9. afroman006

    afroman006 1/2 ton status

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    HHMMMM /forums/images/graemlins/thinking.gif So knock sensor it is. I'll go ahead and replace it too. Uhhhhhh... where is it and what does it look like? I've heard that the larger tires and stock gears can mess with a TC. Is this true? Right now I'm rolin on 36's and 3.73s. 4.56's on the way though. Thx
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    Knock sensor on a 350 (and 305 too I assume) is on the block just forward of the starter. (towards front of truck) Screwed into the block, kind of mushroom shaped.


    The point of having a scanner is diagnosing the actual component instead of replacing all the things that are related part of the system having a problem. If you wanted something to spit out the codes for you, a paperclip would have been a lot cheaper. /forums/images/graemlins/smile.gif

    As to the TC, I assume you mean torque converter? That shouldn't have anything to do with any codes, the ECM only knows if it's been commanded to engage or not. It can't monitor whether the clutch is actually applied. However, it could be *possible* that if you haven't corrected the speed reading (whether cable driven or electronic speedo, done different ways) it may be so out of whack that the ECM is seeing the wrong vehicle speed for engine RPM/engine load/driving conditions.
     

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