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Computer and tranny?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BrianK5, Dec 30, 2001.

  1. BrianK5

    BrianK5 Registered Member

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    First, where is the computer on an '85 Blazer?
    The previous owner swapped in a vaccuum advance distributor, so that's not hooked up to the computer anymore. If the computer is gone, the lock-up function on the 700-R4 won't function, correct? If the computer is still there, can it be hooked to the tranny, but not the distributor, and still function?

    Thanks,
    Brian

    1985 K5 Blazer
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    No ECM in an '85. TCC (lockup) is its own harness. VSS, engine vacuum, and, at least on cars, engine temp, are required input to control lockup converters.

    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     
  3. scavenger

    scavenger 1/2 ton status

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    Brian,
    I have a 1985 full size Blazer with the 305 motor and 700-R4 tranny. A while back my partially computer controlled Quadrajet took a dump and I replaced it with an Edelbrock Q-Jet. While doing this I also replaced the computerized distributor with a 1979 non-computerized one. I then finally located the ECM behind the glove box (or in that general area) and unplugged the harness. The tranny seems to be operating fine. Because Dorian responded to your post stating that the 85 model dosn't have an ECM (and he may very well be correct) I wonder if mine is really an 85, or what I believe is the ECM really isn't one. The thing I pulled the harness from is an aluminum box that is approx 6 inches wide and maybe 8 inches long........Hmmmm, now I wonder what I really have.
    Pat.
     
  4. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Sounds like the description of an ECM to me. I've got a book (Chilton) that says '83 up has ECM. I couldn't say for sure one way or the other, that book has not proven very usefull.

    Russ

    85 K30 CUCV, 350 TBI, TH400, 205, D60/C14, 4.56 Locked
    Some day: 4" lift, 44" tires, massive cutting, shorter wb and rear overhang.
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    Basically you have to look at how many electrical plugs there are on the carb. My '85/86 parts manual doesn't list a CCC (computer) carb, yet my somewhat incorrect 1986 "preliminary" service manual indicates there was. If the carb has two electrical connections, it would have to have an ECM. If just one plug, the only reference given for any kind of input to that (its a dual capacity pump GM says) is 170 degree coolant temp.

    Chiltons is wrong, my 1983 most certainly did not have an ECM.

    1985 likely has the "electronic" cruise control, but I don't know where that "box" is located for that.

    If the emissions sticker is still there, in the upper left corner is an 11 digit number/letter sequence. The 6th digit is the vehicle class, and if its a "T" the vehicle was a California model, and if any of the '85's got CCC, they would have been the ones.

    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     
  6. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Yeah, I kinda figured Chilton was wrong. Between you and Chilton, I'll go with you until I see it for myself. [​IMG] I only threw that out there because it sounds like he is describing an ECM. Of course, my '85 K30 has and ECM... [​IMG]

    Russ

    85 K30 CUCV, 350 TBI, TH400, 205, D60/C14, 4.56 Locked
    Some day: 4" lift, 44" tires, massive cutting, shorter wb and rear overhang.
     
  7. scavenger

    scavenger 1/2 ton status

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    I can't find the emissions sticker, but the original carb that I removed had a gray colored connector on the top front passenger side of the carb that 2 wires plugged into. It also had a wire for the electric choke, and 1 wire on the drivers side for the solenoid (I think that is what it is) that kicks the fast idle on. I just went out into the garage and dug up the old carb which has a part number of 17085226, and below this it says 1905 HLY. If it warms up I am curious enough to go out and remove the glove box to see if that aluminum box has any part numbers on it so I can figure out if it is an ECM or some other item I should not have unplugged.
     
  8. pcorssmit

    pcorssmit 1/2 ton status

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    The aluminum box above the glove box is the pluter.

    My '83 has the electronic cruise, the module is on a bracket behind the dash bolted to the right side of the steering column. Its red, maybe 3/4" x 3" x 5", and mounts vertically with the wires on the bottom. The VSS buffer kinda hangs under the dashboard, with a wire going to the back of the speedo. Just ripped out the cruise yesterday. I didn't have a pluter originally, but it was also a diesel.

    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  9. BrianK5

    BrianK5 Registered Member

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    Thanks for the replies, I'll have to take a look behind the glovebox tomorrow. I figured it has or had a computer b/c there is a disconnected 4 pin plug in the engine compartment near the distributor(and a few other electrical plugs that go to nothing). That same 4 pin plug runs from the distributor to the computer in my 85 Monte Carlo. It has to be unplugged to bypass the computer while setting the timing. I know that if it did have a computer and it was functioning, there would be a clicking noise coming from the carb when the key is turned forward, just before starting. Mine Blazer doesn't click. I'll have to compare the Q-jet on my Blazer to the CCC Q-jet on my Monte to see about the electrical connections.

    So, if the computer is gone, the TCC will still function b/c it is not part of the ECM?

    Maybe my Blazer's not really an 85, but I'll have to check the VIN to figure that out.

    Thanks,
    Brian



    1985 K5 Blazer
     

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