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1984 K5 Computer

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Chevit, Sep 9, 2004.

  1. Chevit

    Chevit 1/2 ton status

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    O.K. here is a question is this a computer behind the glove box? and if so what does it control?
    1984 K5 Non-Computerized Carb
    I have replaced everything cannot find the original post but been having probs for 10 months now...
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    EST, ESC whatever, its for the electronic spark control system. Basically that, the distributor, and if I'm not mistaken, a knock sensor are the "system".

    Replacing it may not fix the problem if you didn't find it in everything else you did. I'm sure there is a test procedure for it.
     
  3. Chevit

    Chevit 1/2 ton status

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    Found this on the internet what do you think?

    GM issued a TSB is 1982 and again each year until EFI
    replaced the carburetors. The TSB authorized disabling the
    ESC system via cutting the green wire and the black wire in
    the 4 wire harness and jumpering them together on the
    distributor side of the harness.
    The reason for the TSB was numerous complaints due to the
    ESC system being over sensative to random mechanical noise
    in the engine causing the spark advance to retard to the
    point that the vehicles basically couldn't pull cotton out
    of a Kotex.

    http://www.totallychevys.com/chevy/chevy-archives/chevy-trucks/chevy-trucks-p-367.html
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    Dunno if thats the right procedure or not, but if you trust the source, I would go about it smartly.

    Don't cut anything. Pull the connectors, remove the wires they say to remove by *de-pinning the connnector*, jumper the positions they say jumper, and take it for a test drive.

    Problem solved, then thats your issue, and I would say permanently disable the ESC system. ESC isn't all that great, but (assuming you have a 305 here, since I believe ESC was only for those engines) with the compression they were running, the recommended octane, and the crappy heads, it was designed to keep the engine from killing itself.

    It does seem somewhat prone to failure, but since it's an electrical component, more likely blamed when it's not the cause. "Nothing else seems to work, must be the computer!" /forums/images/graemlins/frown.gif
     
  5. Chevit

    Chevit 1/2 ton status

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    [ QUOTE ]

    Problem solved, then thats your issue, and I would say permanently disable the ESC system. ESC isn't all that great, but (assuming you have a 305 here, since I believe ESC was only for those engines) with the compression they were running, the recommended octane, and the crappy heads, it was designed to keep the engine from killing itself.
    /forums/images/graemlins/frown.gif

    [/ QUOTE ]

    swapped out the 305 to a 350 a few years back
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    Does your truck have a knock sensor?

    If it does, dump the ESC system, the knock sensors aren't interchangeable 305 to 350.
     
  7. TruckNutzDude

    TruckNutzDude 1/2 ton status

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    If you fubar your distributor I have one sitting in a drawer waiting for you to have it shipped... It's free if you pick up the shipping. It's the ESC type with the wires on it. /forums/images/graemlins/wink.gif I just swapped in an HEI dist. when I swapped in my 350. I couldn't get the carb. to dial in right even after the swap though... not the distributor's fault. I sold the truck a few months after the swap ( a few years ago) for $800 /forums/images/graemlins/mad.gif I miss that truck.

    Oh yeah, you can jump those two wires and it will run fine. I think it's a purple wire you cut though, not a black one. I forgot so just do what they tell you to. /forums/images/graemlins/screwy.gif
     
  8. Chevit

    Chevit 1/2 ton status

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    [ QUOTE ]
    Does your truck have a knock sensor?

    If it does, dump the ESC system, the knock sensors aren't interchangeable 305 to 350.

    [/ QUOTE ]

    Is that the sensor next to the starter? if so yes
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    Yep, thats it. Dump ESC. 305 knock sensor on a 350 just doesn't work right.
     
  10. Chevit

    Chevit 1/2 ton status

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    Just disconnect it (knock sensor)? what about the dist. cutting the wire deal?
     
  11. dyeager535

    dyeager535 1 ton status Premium Member

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    No. I mean disable the whole ESC system. Not sure what failure mode is, or if the system self diagnoses, but you need to disable the whole thing.
     
  12. Chevit

    Chevit 1/2 ton status

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    Thanks much for your help... /forums/images/graemlins/thumb.gif
     
  13. Chevit

    Chevit 1/2 ton status

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    [ QUOTE ]
    Pull the connectors, remove the wires they say to remove by *de-pinning the connnector*, jumper the positions they say jumper, and take it for a test drive.

    [/ QUOTE ]

    How do you go about depinning these to wires before I screw somthing up?
     
  14. dyeager535

    dyeager535 1 ton status Premium Member

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    Well, since you definitely need to remove the system, I wouldn't worry too much about testing.

    However, to make sure you don't CUT the wrong wires, de-pinning and testing first isn't too bad of an idea. At least right now the truck runs. Want to put it back that way if something isn't right with the wiring instructions.

    Not positive what the connectors look like, but there are probably multiple blades inside the connector, one for each wire. (if you look at the underside of the connector) On almost all of the GM connectors like that, your vintage, if you straighten a paperclip, and push it in from the blade side (as opposed to the wire side) right in the middle of the blade (on one side or the other, I believe typically the side that has the locking tab on it has a slot in the plastic of the connector) until the paperclip stops, then gently pull the wire, it should slip out. If it doesn't come easy, don't force it.

    A good trick is that before attempting to use the paperclip, push the wire into the connector, while holding the connector with your other hand. The wire has some "play" in the connector because of the locking tab. You "unload" the tension on that tab by doing this, which makes depressing it with the paperclip much easier.

    Then you can just stuff a wire with two bare ends into the two cavities you removed the wires from, to act as a jumper.
     
  15. 84_Chevy_K10

    84_Chevy_K10 Banned

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    I would seriously swap in a distributor without ESC. I'll look for the link, but there is definitely more involved with disconnecting it than simply removing the wires.

    Mine shorted and I had no spark. This as about 5 years ago when I first got my truck. Stumped the shi* out of me after replacing the module and still no spark, replaced the pickup coil, no spark (this is before I knew what I was doing) and finally I said screw it, dropped a different distributor in and she ran great.
     
  16. Chevit

    Chevit 1/2 ton status

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    It is a black connector with a green rubber seal, with four male connectors on the distributer side, do I want to jump the distrbuter side or the other side?
     
  17. dyeager535

    dyeager535 1 ton status Premium Member

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    I thought there was too...but isn't it basically a "standard" distributor with a module that somehow retards timing based on knock sensor feedback? Still has vacuum can and mechnical advance weights?

    I would think that with the proper wiring, you just end up "tricking" the module into thinking there is never any problem "seen" by the knock sensor, thus timing is never influenced by the retard function.

    If it's got a green rubber seal, that probably means it's a weatherpack connector, which requires (IMO) a special tool to depin, since they don't use blades. It might also be another style, can't remember the name, but I haven't tried to depin those. Could be wrong, but I've never seen a blade connector with a green seal on it.


    If the writeup you posted is correct, it APPEARS you want to screw with the wires near the distributor, with everything still connected.

    What Tim might be saying is that wherever those 4 wires go, they need to still get power somewhere, which means without some work to swap everything over, swapping in a non-ESC distributor is easier.

    If you can't depin the connector, I would probably lean towards just replacing the distributor. We already know it doesn't work right for a 350, so you have nothing to lose if you can get another working distributor to swap in.
     
  18. 84_Chevy_K10

    84_Chevy_K10 Banned

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    I searched and searched, but I can't find the write up I have seen before that shows you how to eliminate the ESC side of the module without the input.

    If you disconnect it, it will go to full retard all the time. In my case it shorted somewhere and I had no spark. I was 16, this was my daily driver, and I had no vehicle for a week while I chased down the problem. Really pissed me off. /forums/images/graemlins/angryfire.gif /forums/images/graemlins/angryfire.gif

    5 years later, had HEI, now have an MSD box, no problems with either.

    Those four wires go into the cab to a small computer module. I finally removed mine when I had the box out to put the heater core in.

    I hate ESC with a passion, really....get yourself a 4 pin distributor or buy an MSD box and eliminate that crap.
     
  19. cwn anwyn

    cwn anwyn 1/2 ton status Premium Member

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    I searched for it. Dont know if this is the one you saw, but it covers it pretty good. ESC/ HEI
    z /forums/images/graemlins/thumb.gif
     
  20. Chevit

    Chevit 1/2 ton status

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    First thing to do is unhook the spark control computer lead from the pink wire and hook the pink wire directly to the dist. cap.

    Which pink wire are they talking about? Or do I even need to mess with it?
     

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