Window regulator and motor replacement are easy, but diagnosing the system can be difficult on late-model
vehicles. So before you order the parts and pull the door panel, there are new technologies
and diagnostic strategies you need to understand. First, the switch for the window is not directly
connected to the window. The switch is just an input to a computer module that actuates the
window. Second, all modern power window systems since the 2011 model year have automatic reversal,
or anti-pinch technology. Many manufacturers implemented this technology as far back as 2003.
This technology uses hall effect, and or current sensors, to measure the movement
and force of the window. This feature prevents an occupant from being injured by a closing window.
Third, a power window system can be connected to the security system and other systems on the
vehicle. This connectivity allows the customer to control the windows with a keyless entry remote.
Mazda and Ford call this a "global close feature".
For this to happen, three modules on the vehicle have to communicate to open or close all the
windows when the vehicle owner holds the lock or unlock button on the remote for 5 seconds.
With these new layers of complexity, come new diagnostic strategies and installation procedures.
Blindly replacing a window regulator and motor assembly may not solve a customer's problem,
but it's not all doom and gloom. These new technologies make it easier to confirm the
cause of a failed window regulator without having to remove the door panel. Here are some techniques
you can use to diagnose a window regulator and or motor assembly before removing the door
panel. Many of these methods are from domestic and import auto makers, but they can be applied
to most vehicles with power windows. The first step is to record the vehicle owner's complaint.
Merely stating the window is not working, is not enough detail. Many late-model window problems
could be intermittent, or could involve the anti-pinch and auto-reversal mechanisms. These
notes are critical to the technician to duplicate the problem. Once the issue can be reproduced,
inspect for obvious faults like physical damage or a blown fuse. If the vehicle owner is complaining
that the window goes up, but then comes back down, check the anti-pinch operation. Some
OEMs recommend the paper towel roll method. Take a roll of paper towels and put it in the path of
the window. The window should hit the paper towel roll and automatically retract. Often,
restriction in the tracks and regulator can also set off the anti-pinch system. Before you pull off
the door panel, you can confirm the operation of the module switches and motor with a scan tool.
Looking at the live data stream, you can see each press of the power switch through the power window
control module or body control module. This is a recommended procedure in the service information
for many auto makers for diagnosing a window problem. With a scan tool, you can actuate the
window using bi-directional commands to confirm the operation of the motor. Another trick, if
dealing with an intermittent operation complaint, is to look at the other modules connected to the
power window control module or body control module. If these modules fail to communicate,
the other modules will generate codes that have lost communication with the window module.
If you have still not confirmed the problem, there is one more check you can perform before
you remove the door panel. If you can access the wiring harness in the door jamb, you can check the
voltage and current going to the motor. Using a wiring diagram, you can find the power wires
to the motor and measure current drawn by the motor with an amp clamp connected to a multimeter
or scope. BMW released a TSB on this diagnostic tactic where they said the initial current spike,
when the button is pressed, should be around 19 to 20 amps. This method can also help to spot damaged
tracks and bound-up cables and linkages. If you need to confirm there's power going to the motor,
you can back probe the connectors at the door jamb. If a connector is not in a convenient area
with a piercing probe, you can measure voltage when the button is actuated. Just make sure you
repair the insulation on the wire with electrical tape, liquid electrical tape or other products.
When you replace the window regulator, pay special attention to the tracks, clips and linkages.
Any extra resistance can cause another failure and possibly cause the anti-pinch system to
activate. Excessive dirt in the track and channels needs to be removed and then lubricated with a dry
film lubricant. Another tip is to make sure you have new plastic fasteners, that are often called
Christmas trees, to secure the door panel to the door before you start the job. Many of these
fasteners are damaged when they're removed, but we're not done yet. After the window regulator
is installed, you need to carry out procedures to initialize the auto close and open functions.
These procedures tell the control module the upper and lower positions of the window. This process
must be performed in under 43 seconds. If the procedure is not performed in time, the auto open
and close function will not work. Also, the global close or open will not work with the keyless remote.
Some vehicles require the window switch to be held for three to five seconds in the fully up or
down positions. Others may require a scan tool to reset or normalize the system. If the recommended
procedure does not work, you might need to check for codes in the module for the power window
system. Another item holding up the process might be the battery. A weak battery can be discharged
during the repair process. This could cause a condition where the system voltage drops below
a level of seven to ten volts when the switch is pressed. When the voltage drops, modules can shut
down or lose communication. Charge the battery and try again. In 2019, only five new vehicles could
be ordered with manual crank windows. For most vehicles, power windows are standard equipment,
so it makes it that much more important that you follow these tips to properly diagnose them.