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Thread: Wiper Interval Regulator hack?

  1. #1
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    Default Wiper Interval Regulator hack?

    My 88 Sport has occasionally over the years exhibited sudden loss of wiper function. Lately it is more common and getting worse. The problem seems to be common to cars w/ interval wipers. Symptoms are: Dead stop of wipers wherever the blade is at, no power at the Y/R #61 terminal at wiper motor. That 12V power to terminal #61 comes through the Interval Regulator via the Reset / Governor Relay. I have been examining the innards of that Interval Regulator and can see this much: The Reset / Governor Relay is controlled by switching transistor Q3, which can in turn be activated by either Q1 or Q2. One of these three transistors is the prime suspect, as when the power failure occurs I can correct it by touching the -coil terminal of the R / G Relay with a test lamp (relay function OK, trouble is in control ckt). I can see that Q1 and Q2 are flat-sided plastic body transistors with pins arranged CBE, and Q3 is layed out EBC. I could buy a new Regulator online but would rather fix the old one. I want to try replacing the three switching transistors and see if the intermittent loss of wipers is fixed, but am not sure how to select replacement transistors. What am I looking for? There are a Zillion transistors that all look the same... how do I select the correct ones?

  2. #2
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    if they are half round so to speak,,i have a lot of transistors,

    304 772 3411

    i was under the impression intermittant wipers was a ground wire up at the motor itself... i think Eric solved this a while back.

    id be interested in participating in this with you as a project,

    all you need is the pn on the side of the transistor , then cross ref it to another if its not available.

    i have no clue if there is a wiring diagram for the regulator or not but that would help us know which ones are common base/emitter or collector ,, darlingtons or whatever.

  3. #3
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    on my 20th i cant tell you if there is even one in my car,, there should be but its amazing how this setup offered such a difference in actual little black box options.

    one thing that we can do is with a known good unit, get live voltage readings on the board. im betting there are markings on the board call TP1, TP2 etc.

  4. #4
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    Every time ive had an issue, the motor itself died or the ground was dirty. Never had to replace the "black box", couldn't even tell ya where it is.
    Quote Originally Posted by jcassity
    I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
    Hooligans!
    1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
    1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
    1986 cougar.
    lilsammywasapunkrocker@yahoo.com

  5. #5
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    motor OK, park relay serviced. It's the Interval Regulator and I suspect the trouble lies with one of the 3 switching transistors. I can see that Q3 controls the suspect power relay and either Q1 or Q2 can trigger Q3. Beyond that is guess work. My enthusiasm wanes. I'll probably buy a NOS unit.

  6. #6
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    Here is a link to a SHO forum, where a guy fixes one of these modules. I didn't join the forum to look at the pictures.
    https://shoforum.com/index.php?threa...module.120313/

    An old EEC IV schematic I found uses a TIP121 transistor to drive the fuel pump relay pin 22. Provides the ground to pick the relay.
    For what it's worth, probably nothing.
    Attached Images Attached Images
    Last edited by softtouch; 09-07-2018 at 01:07 PM.

  7. #7
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    Here is a schematic where someone rewires the module to make it work?
    It shows Q1 is a 2N3055 Q2 is a 2N3904 Q3 is a 2N390?

    Save the pic and open it with something that you can zoom with.
    Attached Images Attached Images

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    thanks, softtouch, that is precisely the sort of info that I wanted. I have saved the image and will study it. But in the interim the symptoms have not exhibited and so I reinstalled the old unit. The likelihood that the unit would survive the surgery vs. the current price of a NOS replacement made up my mind; spend the $ now or spend it later. I voted for later.

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