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Why isn't my cruise control working with my new SM-465???

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by KrebsATM02, Mar 8, 2003.

  1. KrebsATM02

    KrebsATM02 1/2 ton status

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    Why isn\'t my cruise control working with my new SM-465???

    I just swapped in a sm-465 into the blazer and now my cruise control doesn't work. It had a 700-R4 and worked fine. Does it have to do with the plug that went into the 700-R4?? Got a 700 mile road trip tommorow~!!! HELP! - Doug
     
  2. HarryH3

    HarryH3 1 ton status Author

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    Re: Why isn\'t my cruise control working with my new SM-465???

    Did you put the cruise control shutoff switch onto the new brake pedal correctly? It has wires and a vacuum line going to it. If that isn't setup right, then the cruise will think the brake is pressed and won't engage.
     
  3. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: Why isn\'t my cruise control working with my new SM-465???

    What's cruise control?
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: Why isn\'t my cruise control working with my new SM-465???

    Not sure how integrated Cruise Control is with the TBI systems (it's not at all on the early carbed setups) but if it is, and you swapped the 465 for 700, *and* the vehicle still thinks its in park all the time, you'd have problems. (you *didn't* ground the park/neutral switch for the swap did you?)

    Since apparently the TBI/465 trucks didn't use the VSS either, at least for some years, and cruise needs it, that could be another source for your problem.
     
  5. HarryH3

    HarryH3 1 ton status Author

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    Re: Why isn\'t my cruise control working with my new SM-465???

    If it's a 4WD, the VSS should be on the transfer case. /forums/images/graemlins/cool.gif
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: Why isn\'t my cruise control working with my new SM-465???

    But where does the VSS go? Through the DRAC and into the buffer, or how else is it routed? Earlier VSS got the signal from the speedo head and that went straight to the cruise control box, later on, that may have been an ECM output (cruise/VSS signal) and if it is, screwing the ECM up by making it think the vehicle isn't moving all the time, would be a sure fire way to disable cruise.

    If the cruise box is still seperate (over the accelerator pedal) AND the VSS signal still goes directly to it BEFORE the ECM, he'd be ok.
     
  7. HarryH3

    HarryH3 1 ton status Author

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    Re: Why isn\'t my cruise control working with my new SM-465???

    Being an '88, it should get the signal from the buffer. The park/neutral switch may be part of the setup, to prevent the cruise from blowing the engine if the trans gets shifted into neutral on the highway. The fact that he had to swap out the pedal assembly to go from auto to manual is what made me wonder if the cruise "brake switch" is out of whack.
     
  8. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: Why isn\'t my cruise control working with my new SM-465???

    I'm really surprised how the TBI trucks are wired, you would think that they would more closely have mirrored the earlier cars, but such is not the case as we know.

    I think you are right about the buffer though, the DRAC was electric speedo only, so not applicable in this case. Not sure on the cruise, I can't believe it wasn't integral with the ECM by then (no seperate box), along with TCC, but maybe not.

    You are more than likely correct with the switch (not adjusted correctly for the new pedal setup, or not plugged in at all) but going from 700 to 465 makes me wonder if the ECM was changed out too /forums/images/graemlins/smile.gif May or may not have something to do with this instance, but there can certainly be problems if the original ECM is used.
     

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