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HEI Module swap...

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Greg72, Jul 29, 2003.

  1. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    OK guys I'm swapping out the HEI ignition module in my '88....

    Pretty simple, except for the two wires under the rotor area (one yellow, one green)...they pulled off before I could notice which one went where.

    The module is labelled "P" and "N" where the wires go..... any chance that "P" = positive (yellow wire?) and "N" = neutral (green wire)?????

    Any quick responses would be great....since I'm covered in grease and trying to get this right! /forums/images/graemlins/cool.gif
     
  2. mike reeh

    mike reeh 1/2 ton status

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    Arent the spade connectors different sizes?

    If they will fit either way and theres nothing obvious that says which way they go, then in my opinion that means hook em up any way you want and fire it up. if it dont work, swap em. no harm done

    YMMV, as mj says.


    mike
     
  3. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Well one of the things I discovered, is that the two wires are supposed to be mounted in a small plastic Molex connector......mine are NOT.

    When I looked at the setup, it seemed odd that there would be two non-insulated connectors so close to each other, especially with so much metal in the surrounding area... as far as I can tell the plastic insulator has broken off and is now long gone (or is taking up residence in other parts of the distributor)!!!

    In any case, with those two wires exposed there may now be a blown fuse in the fuse block to replace, and this may explain why the truck suddenly "konked out" the other day.

    I already swapped out the fuel pump relay (a quick and cheap test).... when that didn't work, the ignition module seemed like another common area to check.


    Hmmmmm...... /forums/images/graemlins/thinking.gif
     
  4. Thunder

    Thunder 3/4 ton status

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    I think Those are the wires to the pick up coil.(mine are green and white in my 89) They really should be insulated.
    If they short out the module will see no spark signal and not give spark.
    I dont think they will blow a fuse if they short to ground they are not fed 12v as far as i know. They feed a small voltage induced in the pickup coil to the dist mod telling it when the cylinder is at TDC.
    The only way to fix it right is to get a new pick up coil 20-30 dollars. But you have to pull the dist to put it on. /forums/images/graemlins/frown.gif
    If you have a ohm meeter the reading between the wires is 500 to 1500 ohms if out of those specs the pickup coil is bad.
    Replace the module too.
     
  5. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Thunder,

    Thanks for the info.....I was already warned about having to pull the dist to fix that broken connector ( /forums/images/graemlins/frown.gif)

    The spec on the module resistance is great though....I can check that on the one I pulled out, as well as the new one that's in there.


    /forums/images/graemlins/thumb.gif
     

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