Intermittent wiper conundrum

I seem beset with weird issues lately. The rainy season has finally hit the Pacific Northwest. The intermittent wiper setting on my car works great when it isn't raining. 'Never fails! But as soon as there's any serious precip, no dice: the wipers just stop unless I turn them on full. Is there a logical explanation for this, or is it just bad "carma"? (BTW, the car was built in 1983, so no fancy digital/sensor-based logic: just analog timing, I'm sure.)

Anyway, although I was tempted to disassemble the wiper relay module to probe and possibly repair it (sketchy cap, perhaps?), I broke down and ordered a replacement online. But who knows, maybe I'll gut the module housing and build an optical-sensor-based Propeller system that automatically determines the correct wiper speed for conditions ...

-Phil
“Perfection is achieved not when there is nothing more to add, but when there is nothing left to take away. -Antoine de Saint-Exupery

Comments

  • 26 Comments sorted by Date Added Votes
  • So what's the problem - sounds like it works intermittently to me? >.>
  • Funny, one of my MBs has exactly the same problem, works fine when not raining, when raining just works on fast.

    My go to website www.benzworld.org claims that one needs to disassemble the wiper assembly and re-grease it.

    It looks like wiping off water is harder then just wiping over a dry window.

    Enjoy!

    Mike
    I am just another Code Monkey.

    A determined coder can write COBOL programs in any language. -- Author unknown.

    The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this post are to be interpreted as described in RFC 2119.
  • The intermittent wipers depend on a switch or contact in the wiper assembly to let the electronics know that a full wipe has been performed so that the delay can ensue. This is most likely a mechanical switch which is not shall we say IP69 sealed from the elements. It is this contact which is preventing the wiper circuit/controller from performing because it's not giving data the controller understands. It is almost certainly built into the wiper motor and needs to be cleaned and, possibly as msrobots suggests, greased to protect it from the elements.
  • localroger wrote:
    The intermittent wipers depend on a switch or contact in the wiper assembly to let the electronics know that a full wipe has been performed so that the delay can ensue. This is most likely a mechanical switch which is not shall we say IP69 sealed from the elements. It is this contact which is preventing the wiper circuit/controller from performing because it's not giving data the controller understands. It is almost certainly built into the wiper motor and needs to be cleaned and, possibly as msrobots suggests, greased to protect it from the elements.
    Hmm. This sounds right. It also explains my inability, at times, to turn the wipers off, since they don't know when they're in the down position.

    Thanks, guys!

    -Phil
    “Perfection is achieved not when there is nothing more to add, but when there is nothing left to take away. -Antoine de Saint-Exupery
  • What I can't understand is why the wiper control is so over engineered yet works so poorly. One push button and a 50 cent micro is all that is needed for dual speed and intermittent wiper control.
    In science there is no authority. There is only experiment.
    Life is unpredictable. Eat dessert first.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 21,240
    edited September 30 Vote Up0Vote Down
    kwinn wrote:
    One push button and a 50 cent micro is all that is needed for dual speed and intermittent wiper control.

    True, but my car was built in 1983. There weren't any fifty-cent micros back then. So, basically, it's a transistor circuit with a timing cap that drives a relay.

    But even the most reliable timer/pulser circuit has to rely upon a limit switch that tells the circuit when the wiper is in a rest position. And if that switch gets wet or wears out, the circuit -- no matter how sophisticated -- is at a loss to function properly.

    Based upon what msrobots and localroger have told me, I probably wasted my money on a new timer circuit, when the problem lies elsewhere.

    -Phil

    BTW, there's a movie well worth watching, Flash of Genius, about Robert Kearns, the inventor of the intermittent wiper system, who sued the auto industry for patent infringement when they usurped his invention. I saw the film on Netflix. It might still be available there.
    “Perfection is achieved not when there is nothing more to add, but when there is nothing left to take away. -Antoine de Saint-Exupery
  • I didn't know cars had wipers in 1983
  • Heater.Heater. Posts: 19,729
    edited September 30 Vote Up0Vote Down
    Sure they did Bob.

    When the guy at the gas station had finished filling your tank for you he would check your oil level and tire pressures and give the windscreen and headlamps a quick wipe down.

    All part of the service.

    He would then crank the starting handle to get the motor going and ones chauffeur could then continue the drive. One was hardly distracted from reading one's Financial Times in the back seat.

    Times were good in '83.

  • Cluso99Cluso99 Posts: 12,851
    edited September 30 Vote Up0Vote Down
    Even my 1958 VW had wipers, and a speedo. Reserve fuel tank operated by a foot lever saved having a fuel gauge.
    Mind you, the wipers were crap at much speed. But then again, in the wet you couldn't drive fast if you didn't want to slide out, or roll ! ;)
    My Prop boards: P8XBlade2, RamBlade, CpuBlade, TriBlade
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  • Heater. wrote: »
    Sure they did Bob.

    When the guy at the gas station had finished filling your tank for you he would check your oil level and tire pressures and give the windscreen and headlamps a quick wipe down.

    All part of the service.

    He would then crank the starting handle to get the motor going and ones chauffeur could then continue the drive. One was hardly distracted from reading one's Financial Times in the back seat.

    Times were good in '83.

    Hello!
    You're thinking of 1953, as in "Back to the Future". where our hero sees a crowd of station attendants surround one guy's car. Of course that continued into the middle 1960s, and eventually ended. Now the wipedowns are done by the driver.
  • PublisonPublison Posts: 9,736
    edited September 30 Vote Up0Vote Down
    Heater. wrote: »
    Sure they did Bob.

    Now the wipedowns are done by the driver.

    Or the uninvited on our city streets.


    350 x 240 - 87K
    Infernal Machine
  • Heater.Heater. Posts: 19,729
    edited September 30 Vote Up0Vote Down
    Buck,

    '53, '83? Bah! What's three decades when one is my age?

    I do miss the Bentley though. And old James could have taught these new fangled self-driving cars a thing or two about driving. If it's a choice between your master and the peasants in the street, save your master.
  • I ounce drove an International scout that had vacuum wipers. Every time you floored the gas the wipers would slowdown.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 21,240
    edited September 30 Vote Up0Vote Down
    DigitalBob wrote:
    I ounce drove an International scout that had vacuum wipers. Every time you floored the gas the wipers would slowdown.
    My first car, a '66 Rambler American, had those. The vacuum piston eventually lost its seal, and the wipers would only wipe in one direction and stop until the car was idling. I had to add a coil spring mounted to a right-angle bracket on one of the wiper arms to equalize the wiping forces so the car would pass inspection when I relicensed it in Washington.

    I'm surprised the Benz wipers aren't vacuum driven. Everything else in the car is, including door locks, gas cap lock, trunk lock, power-assisted steering, and engine shutoff. Pulling up the floor mats reveals a maze of color-coded plastic vacuum tubing, eventually running to a "vacuum reservoir" in the trunk. The weirdest problem I ever had with this system was an inability to shut off the engine unless the driver's door was locked. It was caused by a leaky lock piston in that door.

    -Phil
    “Perfection is achieved not when there is nothing more to add, but when there is nothing left to take away. -Antoine de Saint-Exupery
  • Buck,

    The Flux Capacitor used in Back to the Future was invented in 1955, which happened to be exactly 30 years from when the movie starts in 1985.
  • Genetix wrote: »
    Buck,

    The Flux Capacitor used in Back to the Future was invented in 1955, which happened to be exactly 30 years from when the movie starts in 1985.

    Ah but he came with the idea after some strange acrobatics in his bath.

    As for 1953, so? It depends.
    Besides when it comes to time travel, I prefer police call boxes.
  • Reminds of late 60's Chevy Corvette and Camaro with hideaway headlights. The light switch would leak vacuum and would give off a hissing noise that would vary with acceleration.
  • Today I received the new wiper module. Of course, in the interim, the wipers magically started working again. I can only conclude that simply ordering the replacement module was adequate to solve the problem: no need to actually install. Or perhaps the old module sensed an impending layoff and decided to get its act together. At least I wasn't threatened with a suit over age discrimination!

    -Phil
    “Perfection is achieved not when there is nothing more to add, but when there is nothing left to take away. -Antoine de Saint-Exupery
  • Had exactly the opposite happen!

    We were replacing the mini computer with a new model. Both were installed in the computer room for a couple of weeks. In that time, the old mini had more failures that it had in the entire 4 years. Its reaction to being replaced ;)

    In truth, it was hot weather, and the additional load, the air conditioner just couldn't cope. The old parts were just more temperature sensitive than the newer parts :(
    My Prop boards: P8XBlade2, RamBlade, CpuBlade, TriBlade
    Prop OS (also see Sphinx, PropDos, PropCmd, Spinix)
    Website: www.clusos.com
    Prop Tools (Index) , Emulators (Index) , ZiCog (Z80)
  • Phil,

    Have you tried the first technician's rule, hit it with something :P
    If that doesn't work then get a bigger hitter.
  • Genetix wrote: »
    Phil,

    Have you tried the first technician's rule, hit it with something :P
    If that doesn't work then get a bigger hitter.

    Had a few calls for customers that followed that philosophy. Not a pretty sight or a small bill.
    In science there is no authority. There is only experiment.
    Life is unpredictable. Eat dessert first.
  • My Citroen BX19 GTi once decided to stall when I stopped suddenly, braking hard, at a roundabout entrance that was just off a busy exit ramp from a motorway. It refused to start again. Dead as a dodo.

    I called the RAC. The guy came out and spent a few minutes poking around under the hood. To no effect. Then a strange thing happened. He walks away and sits on the crash barrier by the side of the road. I wonder what's going on. After a few minutes of meditation he goes to his tool box, pulls out a big rubber mallet and uses it to deliver a single whack to something in my engine bay really hard. Boom, the car starts again.

    WTF?

    He explained that my Citroen had a relay that would cut the fuel supply in the event of a sudden stop. To prevent fire in a crash I guess. As I had stopped hard at the roundabout when the fault happened he figured that really had triggered. Being a bit old it then got stuck. It just needed some violence to unstick it.




  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 21,240
    edited October 9 Vote Up0Vote Down
    When I was driving an earlier model Mercedes diesel, I kept a broom handle in the trunk. The car had developed a starting problem, and my mechanic suggested that a replacement starter would be outlandishly expensive and that my problem was a stuck solenoid. He suggested the broom handle, the purpose of which was to reach down under the hood and whack the solenoid a few times to release it. (That got a little sketchy when the car was parked at a remote trailhead in the Olympics.)

    It actually worked for awhile, but eventually I had to pay the bucks for a new starter.

    -Phil
    “Perfection is achieved not when there is nothing more to add, but when there is nothing left to take away. -Antoine de Saint-Exupery
  • When our kids were old enough to get their drivers license we got them the family heirloom, a 1973 VW. Often it would break down.

    Much later they told me that one day the accelerator cable broke/stuck on our daughter. She called her older brother to help. He sat on the rear bumper, manually trimming the accelerator, while she drove the short distance home. Lucky I didn't know this until years later ;)
    My Prop boards: P8XBlade2, RamBlade, CpuBlade, TriBlade
    Prop OS (also see Sphinx, PropDos, PropCmd, Spinix)
    Website: www.clusos.com
    Prop Tools (Index) , Emulators (Index) , ZiCog (Z80)
  • Many years ago my brother was driving me to pick up the old van that I used to haul my go carts to the race tracks. When we stopped for a red light just around the corner from where it was parked the engine would not accelerate when the pedal was pressed. I got out and pushed it into the parking lot, popped the hood, and found that the throttle cable had broken. Found the cable from one of the go carts worked just fine.
    In science there is no authority. There is only experiment.
    Life is unpredictable. Eat dessert first.
  • Heater.Heater. Posts: 19,729
    edited October 9 Vote Up0Vote Down
    Ah, the good old days.

    When you could actually fix stuff that broke.

    When domestic radios, TVs and all kind of electronics test gear came with it's circuit diagrams and BOM.

    I feel so helpless today. Everything is a black box and generally un-fixable.

    How are we ever to get control of our lives back again?

    I was kind of encouraged by the guy who hacked his Tesla so that he could talk to the Linux OS underneath.

    See the WreckLA:





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