Scan Tool Wiper Diagnostics: Service in Today’s Networked Module-Based Wiper Era
Windshield wipers are an integral component on almost anything that moves, including planes, boats, trains, cars and trucks. And if you think they really haven’t changed much since Mary Anderson invented them in 1903, you are mistaken.
Sure, wipers have progressed from the hand and vacuum operated units of yesteryear to today’s 12 volt electronically integrated systems, but like everything else on today’s vehicles, the wiper system evolution continues.
The use of a scan tool to diagnose wiper issues is now the norm. Retrieving trouble codes to aid in diagnostics, accessing bidirectional controls, initialization, setup procedures and even software updates now require the use of a scan tool.
But the use of a scan tool for wiper service isn’t the only change that the wiper system has undergone. The wipers’ mechanical operation has progressed as well.
Changes in operation
The principle of almost all windshield wiper drive system has been the same for a long time. A motor drives a set of gears that connect to a crank arm that creates a circular motion.
The wiper motor connected crank arm is attached to a linkage that creates a reciprocal motion that moves the wiper arms to clear the windshield. These parts can be bulky and need space for movement. Remember the size of the wiper assembly on a 1997-2005 U-body (Venture/Montana) GM minivan? This system was huge and cumbersome, taking up lots of room under the hood.
The idea of removing all the intricate, bulky linkages needed to drive the wiper arms and replace them with small, individual computerized motors that drive each wiper arm separately was conceived.
The direct drive wiper motor and its service differences
Ford has been using the direct drive method on the Escape (2013 and up), Fusion (2013 and up) and Focus (2011 and up). This design allows separate motors to drive each wiper arm independently. This frees up space under the hood and cowl area that would have previously been taken up by the wiper transmission and its linkage. These characteristics lead to improved wiper efficiency, better total wiper clearing area, fewer parts, space savings, reduced weight and wiring complexity.
The key to Ford’s direct drive wiper system is a reversible encoder motor assembly that drives each wiper arm independently. Each wiper motor assembly contains the needed electronics and internal sensors (reporting wiper arm position) to control wiper speed, park position, service position, winter park position, over-heat and load protection. These motors are versatile and can be programmed to go as close to the A pillar and as low into the cowl area as the manufacturer wishes, all with minimal wiring and weight.
Each of Ford’s direct drive wiper motors require 12 volts, a ground circuit and communications circuits to operate. The use of a local interconnect network (LIN) communications circuit links one motor to the other and to the body control module (BCM) controlling the wiper function. Because the BCM is sharing information from other vehicle modules, features such as speed sensitive wiper operation, rain sensor integration, courtesy wipe function or headlights on with wiper operation is easily programmed and controlled.
Because each wiper motor works independently, each motor needs to know exactly what the other is doing (wiper arm speed and location) so they don’t get tangled.
The driver’s side (left) wiper motor is the primary motor. It coordinates and controls the operation of both motors (and the washer pump on Focus and Fusion from 2014) using a private LIN that links to the passenger side wiper motor. The driver’s side wiper motor is also connected to the BCM via another LIN connection.
If you are doing wiper arm, wiper motor, windshield replacement or cowl service on one of these Ford models equipped with direct drive wiper motors, checking your information service for the proper procedure should be your first step, before the wiper arms are removed.
These direct drive wiper motors aren’t geared or mechanically linked to each other and when the key is off the wiper arms can be easily moved anywhere on the windshield. This free wiper arm movement results in significant changes to the way that these systems are serviced.
To remove the wiper arms on these Ford direct drive wiper motors, they must be placed into the locked position. To enter the locked position, cycle the wipers for one complete wipe cycle to the parked position and then turn the wiper switch off but leave the ignition on. This puts the wiper motors in the locked position to allow service. But this locked position will only last about five minutes or until the vehicle goes into battery saver mode, so you must pay attention to the time. With the wiper motors in the locked position, mark the wiper arm positions (factory windshields have alignment marks, and the left wiper is always positioned above the right) and remove them. Once both arms are removed you can now turn the ignition switch off.
When reinstalling the wiper arms, they need to be installed in the exact same position that they were removed from. Again, the ignition is turned on to lock the motors. This allows the arms to be reinstalled using your marks or the factory marks. If there are no marks on the windshield there are measurements (found in the service information) that will locate the wipers on the windshield relative the cowl.
In some cases, a wiper initialization procedure is required (year/make/model dependent) and a scan tool is required to perform this operation, so checking service information is important.
There is a recall (NHTSA campaign 12V149000) affecting certain 2012 Focus models, due to a corrosion issue in the right-side motor for a missing or failed weather tight seal on the motor’s electrical connection. This Ford direct wiper system will also generate fault codes, created by communications errors or motor issues and a scan tool will be needed to properly diagnose those faults.
Trouble codes BCMs, networks and wiper control
Today’s wiper systems are nearly all controlled by a networked module of some description, depending on what the manufacturer chooses. This module control of the wiper system also means that diagnostics may not be as simple as in the past when using a regular 12-volt test light was acceptable.
Many vehicles now use the hood switch as an input into the operation of the wipers. The result is that the wipers will not function when the hood is open, so it is vital to ensure that a simple hood switch isn’t the issue with non-functional wipers/wiper motors before digging into a complicated diagnosis.
The first step in identifying a wiper system concern should start with a thorough visual and basic inspection; wiring, fuses, grounds and linkages (if equipped) should all be inspected, followed by connecting a scan tool to retrieve trouble codes and diagnostic information. A full system trouble code scan using an up-to-date scan tool should be performed. It’s important to scan all vehicle modules, as the wiper system may not have its own dedicated module.
Wiper systems today are frequently network controlled from another module somewhere on the vehicle, so a code that could assist in diagnostics may not be in the module that you would assume. It could be the BCM, steering angle sensor module (SASM), totally integrated power module (TIPM), steering column control module (SCCM) or any other module the manufacturer selects. Issues such as wipers that won’t turn off, only work on low speed regardless of speed setting or won’t park, are common glitches that can be caused by communications issues, broken or damaged communications lines or total failures in the module that controls the wiper operation.
Common codes, failures and wiper control issues
2011-2014 F-150, Explorer, Edge and MKX: Wipers run on low speed or intermittent even when the switch is off.
An all modules, a scan may retrieve trouble code B1131:08 (wiper motor module bus signal failure) from the SCCM. This code will set if there is a communications issue on the LIN between the SCCM and the wiper motor. With the scan tool connected, look at the wiper switch parameter identification (PID) data. With the wiper switch in the off position, all PIDs should read OFF. If any of the PIDs read ON, then the multifunction switch is the most common cause of this issue. If all PIDs do read OFF, then turn off the ignition and then unplug the SCCM, then turn the ignition on again. If the wipers shut off, this again points to the switch as the culprit.
It’s important to note that the ignition must be off before unplugging the SCCM because the wiper motor will default to the last function that it was performing.
You may have to disconnect and reconnect the battery to reset the default wiper operation on many networked-controlled wiper systems, even after the repair. The F-150 wiper motor (it’s the module controlling wiper motor operation) will remember the last functional operation mode that it received and could default to this mode even after a repair. Disconnecting the battery usually resets this issue.
NOTE: Because the wipers are a vital safety requirement, if the network control fails that controls the wiper motors operation, the wiper motor will usually default to a low speed continuous operation regardless of the wiper switch position, until the full network control is restored.
2008-2012 Dodge Grand Caravan, Town &Country: Wipers run all the time.
An all-modules scan displays trouble code U1149:00 in various modules. This code indicates an issue in the LIN from the multifunction switch or steering control module (SCM) to the cabin compartment node (CCN), aka... the instrument cluster. Testing should start by observing the scan data in the SCM and looking at the wiper switch data with the switch off. But typically, with this code there will be no communications with the SCM module and it won’t show up on an all-module scan. Next, unplug the SCM and check the voltage on the LIN wire. It should be between 7 and 12 volts. If this voltage is present, the likely issue is going to be the SCM itself. Replacement of the SCM is plug and play.
2008-2013 Dodge Grand Caravan, Town and Country: Wipers won’t park and run on low when in intermittent mode.
An all-modules scan may display trouble code B2305. This code indicates that the wiper motor park switch circuit is high. The first step is to clear the code and cycle the wipers three times. If the code returns immediately, disconnect the wiper motor and check for voltage at pin A (brown/gray wire), the front wiper park sense circuit. This wire should have 5 volts, supplied from the TIPM. The wiper motor park switch pulls this circuit to ground when the motor is in the park position (this switch position is displayed in the TIPM’s data stream). If there is no voltage on this wire and the wire’s integrity to the TIPM is OK, then replacing the TIPM should fix the issue (TIPM replacement will require some extra programming steps). If there is the required 5 volts at pin A, reconnect the wiper motor and back probe pin A with a self-powered electronic test light. Watch the voltage indicator lights with the wiper motor turned on. They should flash from power to ground as the switch opens and closes when the wipers reach the bottom of the windshield. If this doesn’t happen, replace the wiper motor.
Service position: VW/Audi and others
Although not related to a failure or diagnostics, many vehicles have wipers that are parked below the cowl and always park there when the ignition is turned off. This can make wiper blade replacement and wiper arm service difficult or seemingly impossible.
Most service information doesn’t help with this procedure, but the vehicle owner’s manual will, as well as information on the internet.
On most VW and Audi models, service position can be activated after turning the ignition off by gently pulling down on the wiper switch stock (within 5 seconds). The wipers will move up onto the windshield and park, entering service position. Many BMWs function the same way.
Nissan’s Juke wiper service mode is reached by turning off the ignition and tapping the wiper stock up twice within 5 seconds, causing the wipers to move up onto the window glass.
Clearing this all up
Electronically controlling every aspect of today’s vehicles isn’t just a trend... it’s become routine, and the wiper system is part of this effort. The precise position control of a direct drive encoder wiper motor allows the wiper blade to get closer to the windshield A-pillar and lower into the cowl on each swipe. This greatly adds to driver visibility and safety, but there are other benefits: The wipers can be placed under the hood edge in the down cycle out of the wind during intermittent operation, resulting in less noise and improved aerodynamics.
Another feature of a computerized wiper system is the ability to move the wipers slightly on a key cycle to stop the rubber edge of the wiper blades from taking a lasting set to the contour of the windshield from the pressure of the wiper arms, increasing the life of the blades. VW/Audi and others have done this, and if the customer is unaware of this feature, it can lead to a complaint that the wipers move slightly during start-up, while this is normal wiper operation.
A scan tool is now vital for diagnosing many wiper-related issues, as is up-to-date service information for effective repairs. Bidirectional controls, re-initializing, finding failed communications networks, components or modules can’t typically be done now without the use of a scan tool. In today’s networked module-based wiper era, the days of just using a 12 V test light for wiper diagnostics is almost behind us. ■
Jeff Taylor boasts a 33-year career in the automotive industry with Eccles Auto Service in Dundas, Ontario, as a fully licensed professional lead technician. While continuing to be “on the bench” every day, Jeff is also heavily involved in government focus groups, serves as an accomplished technical writer and has competed in international diagnostic competitions as well as providing his expertise as an automotive technical instructor for a major aftermarket parts retailer.