Working on Wipers

   It’s right after a major snow storm, and there’s ice and snow 
on everyone’s windshield.  You’re at the shop waiting for the 
phone to ring.   The phone leaps off the receiver, it’s Captain 
Chaos; he’s managed to find a second use for his wiper blades. 
They’ve become a mini snow plow of destruction.  Apparently 
Captain Chaos was in too much of a hurry to clean the ice off 
the wiper blades before turning them on.  In his frantic 
attempt to go to work, the wiper blades have become 
completely useless.  He can hear the wiper motor running, but 
the blades refuse to move. 

   Most likely it’s the nut on the wiper arm that has worked loose from the wiper shaft.   Since most of the manufacturers have gone to this type of fastener, I haven’t seen as many wiper transmission failures due to snow or ice. But there’s always our illustrious Captain who will find some way to break things. 

  There are very few “mechanical” parts on a car that have to work out in the weather as much as the wipers.  People will try anything to make them work better.  I’ve seen the “double” squeegee method, or the triple squeegee… oh, and the “wing” on the arm to help hold it to the windshield at high speed.  Some of which, really do work… some are even factory original, but I wouldn’t put a bet on some of those gadgets out there. The more you try to improve on the wiper blade the more you are going to put the wiper motor and the linkage arms under even more unnecessary strain. 

  Diagnosing most of the mechanical parts of the wiper system is straight forward.  There are exceptions to every rule, so I can’t say that “every” car will be easy.  But I’m sure you’ll be able to figure that out, if and when you come across that issue.  

  Electrically, now that’s another issue.  We can break the systems down by years, and then how to make the repairs or diagnose them.  Prior to ‘95 there weren’t too many complicated electrical wiper systems. To go even further back into history most wiper systems were either vacuum operated or operated by hand.  There are a few exceptions, but most of those are on special models.  Even back in the early ‘80’s Toyota came out with a wiper system that would sense a small amount of rain on the windshield by use of a small black sensor pad on the upper center of the windshield.  I only seen a couple of those, but I’m sure there are other manufacturers with similar systems.  Then there are the systems with interval type wiper systems.  Ford, at one time, made it easy with an interval control module that could be installed into the standard wiper wiring system without much of a hassle.

   After ’96 though, with the arrival of the OBD II systems a lot of the manufacturers had their systems tied into the ALDL connector. You can actually diagnose the wiper system with their scanner.  Some even have codes that involve the wiper system, usually thru the BCM unit or thru the CAN system.  I much prefer the newer cars for the diagnostics capabilities using the factory scanner to operate the front and rear wiper systems. Not to worry though, you can still diagnose the entire system with the use of an ohm/volt meter, but if you ever get a chance to use a factory scanner… you’ll be amazed how much simpler it is to diagnose.

  One of the other things that have changed over the years is how they work, where they have put all the separate components and the nomenclature that each different manufacturer uses.  I pulled the wiring diagrams on a Nissan Sentra, 1985, 1995, and 2005.  The ‘85 model had a separate intermittent amp control module incorporated into the wiper system.  The amp control module was mounted under the dash or near the fuse box.  Its job was to control the intermittent level for the wipers.  By the time 1995 came around the intermittent amp control module was now called a time control module.  They both did the same job; however, it is now mounted at the base of the steering column. In 2005 we get even more compact.  It’s now a variable intermittent wiper control module and is part of the wiper switch itself.  If the test results tell you to change the wiper switch, you also get lucky with the intermittent unit being changed along with it.

  Before tackling any electrical system in any car make sure you have the latest TSB’s, proper wiring diagrams, and any diagnostic information that you can get.  Most good diagnostic manuals will have the impedance values and the voltage ranges in their test procedures.  If you follow the information given, you’ll find that wiper system repairs are not that difficult.  

   As a reminder to your customers, especially in the northern part of the country… make sure to tell them to turn off the wipers before parking the car for the night, and make sure they clean the snow and ice off the wiper arms and blades before trying them the next morning.  A little advice can go a long way, and hopefully keep Captain Chaos on the road, and out of the shop.