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Any way to test the windshield wiper delay module?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by tungsten, Jan 6, 2004.

  1. tungsten

    tungsten 1/2 ton status

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    Vehicle is a 1985 K5 Blazer. The windshield wipers work fine in the "Full On" position but do not work at all in the delay positions.

    I figured it would just be a simple matter of replacing the delay module at the bottom of the steering column, but I read elsewhere that there is a "box" of some sort under the hood that might be bad instead.

    How can I check these two items to find the culprit without just blindly throwing money at the problem and replacing both items at once?

    Or is what I had read elsewhere totally incorrect and it's just a matter of the delay module beneath the steering column having gone bad?

    Thanks in advance.
     
  2. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    I have the exact same problem as you on my 85K5 blazer. Why can't it be up in the delay switch where you turn them on? Could it not be making contact in that switch on our trucks? /forums/images/graemlins/thinking.gif
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    I offered in another post to scan in the '88 camaro wiper troubleshooting section, which looks to be identical for to the truck, if you are interested.
     
  4. tungsten

    tungsten 1/2 ton status

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    [ QUOTE ]
    I offered in another post to scan in the '88 camaro wiper troubleshooting section, which looks to be identical for to the truck, if you are interested.

    [/ QUOTE ]

    That would be great! Thanks. /forums/images/graemlins/smile.gif
     
  5. redbeast

    redbeast Registered Member

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    Mine stoped working also. Here is what I found on mine. In the box that is under the steering column if you were to take it apart (real eazy to do) you will probably find that the diode has opened up (blown). You could proably find a replacement for it at any electronic store like radioshack and replace it yourself...good luck. /forums/images/graemlins/thumb.gif rdg
     
  6. tungsten

    tungsten 1/2 ton status

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    [ QUOTE ]
    Mine stoped working also. Here is what I found on mine. In the box that is under the steering column if you were to take it apart (real eazy to do) you will probably find that the diode has opened up (blown). You could proably find a replacement for it at any electronic store like radioshack and replace it yourself...good luck. /forums/images/graemlins/thumb.gif rdg

    [/ QUOTE ]

    Ah hell if that's it, I'm good to go. It'll make the parents proud that their son finally did something with his electrical engineering degree. /forums/images/graemlins/rotfl.gif
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    Sorry, no power for the last day or so. I'll see what I can do this evening or at latest, this weekend.
     
  8. dyeager535

    dyeager535 1 ton status Premium Member

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    Here you go.

    It looks like the later setups eliminated the inline "module" we have, so I'm not sure if this will even apply to any of our trucks up to 1991. I hope someone on here can get some use out of it. If not, maybe the Camaro guys could.

    '88 Camaro wiper diagnosis
     
  9. tungsten

    tungsten 1/2 ton status

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    [ QUOTE ]
    Here you go.

    It looks like the later setups eliminated the inline "module" we have, so I'm not sure if this will even apply to any of our trucks up to 1991.

    [/ QUOTE ]

    I wonder if the Helm manuals for our trucks cover this sort of thing. If so, I may invest in one soon and will scan/post whatever relevant pages exist.

    They're pretty pricey but it would be worth it to have a comprehensive guidebook for doing troubleshooting like this.
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    I've got an '86 "preliminary" shop manual for the truck around somewhere (what helms sells, except theirs are the real thing) and I can't recall if that is in there or not. It should be. Someone on the board HAS to have a manual for an '85 or later truck. (I *think* '85 is the first for column mounted wiper)
     
  11. tungsten

    tungsten 1/2 ton status

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    [ QUOTE ]
    I've got an '86 "preliminary" shop manual for the truck around somewhere (what helms sells, except theirs are the real thing) and I can't recall if that is in there or not. It should be. Someone on the board HAS to have a manual for an '85 or later truck. (I *think* '85 is the first for column mounted wiper)

    [/ QUOTE ]

    I made some calls and found a reprint of the genuine 1985 shop manual for $88. ChevyDuty sells them for $95. Will add that to my list of things I'd like to own and see if my wife will buy it for me.

    Valentines Day is coming up, ya know.
     
  12. dyeager535

    dyeager535 1 ton status Premium Member

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    Check ebay. May take awhile to find the one you need, but they don't go for that much on there.
     
  13. tungsten

    tungsten 1/2 ton status

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    Okay folks, I am going to take pics of the repair process and do a write-up on this but here is what I have found so far:

    I pulled the delay module out of the truck (found at the bottom of the steering column) and opened it up. Very easy to do.

    Inside is an old breadboard style circuit board. On this are a few common solid state components, one of which is a diode.

    The diode on mine is cooked. Literally. You can see it just by looking at it.

    I was told in this thread that this would be the case and it was -- so apparently it is a common problem with these delay boxes.

    I'm going to Radio Shack in a few minutes and will buy a $.20 diode to repair this $49.00 (ChevyDuty.com) delay box and will see what the results are. If that fixes it, expect a detailed writeup with photos in the next few days.

    /forums/images/graemlins/grin.gif
     
  14. tungsten

    tungsten 1/2 ton status

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    Well... bad news. The diode was indeed cooked and I replaced it, but apparently whatever surge blew the diode also blew some other component(s) in the delay box.

    Rather than try to get some bench time at work with an o-scope and try to troubleshoot this thing further -- especially not knowing what each of the in/out pins are in the connectors or what voltages they are supposed to see -- I will probably just buy another delay box and be done with it.

    Oh well. It was a fun idea while it lasted. /forums/images/graemlins/tongue.gif
     

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