Intermittent wiper conundrum
Phil Pilgrim (PhiPi)
Posts: 23,514
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
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
Comments
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
Thanks, guys!
-Phil
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.
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.
Mind you, the wipers were Smile at much speed. But then again, in the wet you couldn't drive fast if you didn't want to slide out, or roll !
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.
'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'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
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.
-Phil
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
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.
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.
It actually worked for awhile, but eventually I had to pay the bucks for a new starter.
-Phil
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
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:
The new module seems to have cured the problem. So now I'm questioning my stated correlation with precipitation when, perhaps, it had more to do with temperature.
So I took the old module apart to see what lay inside:
It looks like a pretty standard circuit, with a relay and an RC-timed transistor driver. The two electrolytic caps are marked 47uF/16V. Like the villainous butler in a mystery novel, it always seems to be a bad cap in an electronics mystery. So I pulled and tested them. One registered 71uF (!) but, sure enough, the other started at 11uF and crept down from there. So I guess I could've fixed it myself, but the new module was cheap enough that I don't regret buying it.
-Phil
:-D :-D