The Gentex GENFDM3LN Full Display Mirror (FDM®) is an advanced rear vision system designed for automotive use, combining auto-dimming functionality with a high-quality LCD display for rearward visibility. This guide draws exclusively from official installation manuals and user experience reports to provide a detailed, step-by-step walkthrough of the installation process, operational modes, and key technical considerations. The content is tailored for U.S. consumers and DIY enthusiasts seeking to install and utilize the FDM in their vehicles.
Installation Overview
The installation of the Gentex Full Display Mirror requires basic tools and an understanding of automotive wiring. According to the official instruction manual, users must first ensure the vehicle is powered off and the negative battery cable is disconnected to avoid electrical hazards. The factory mirror is typically removed by loosening a T20 Torx screw located at the mirror base and sliding it upward toward the headliner. However, the manual also notes that the removal process may vary depending on the vehicle model.
Before mounting the FDM, users may need to remove certain body panels, such as the A-pillar, to access the necessary installation points. Once the mirror mount is secured, the T20 Torx set screw should be tightened to a torque range of 13.3 to 17.7 inch-pounds. It is important to use specific vehicle adaptors if required, as noted in the manual.
The mirror power harness must be connected to the FDM, and then routed to a location where 12V ignition and ground lines are accessible. Common installation points include the A-pillar, junction block, or overhead compartment. Foam tape and wire ties should be used to secure the harness along the route. Users are advised to locate and tap into the 12V switched ignition and ground supply using T-taps. Ensuring that the T-tap is snapped together is critical to prevent loose connections.
Camera Installation and Adjustment
The rearward-facing camera must be mounted on the vehicle’s rear glass. Users are instructed not to remove the two-way tape liner until the camera bracket is dry-fitted to the intended location. Once the location is confirmed, the two-way tape liner should be removed carefully to avoid contamination from debris or hand oils. The installation manual emphasizes that the adhesive is difficult to remove, and a new bracket and adhesive may be necessary if the process is performed incorrectly.
To install the camera, users should press and hold the bracket against the rear glass for at least one minute, ensuring even pressure is applied. The installation temperature should be above 50 degrees Fahrenheit to maintain proper adhesion. After mounting, the camera can be adjusted up or down on the window bracket so that the horizon appears in the upper third of the mirror display when in display mode.
Once the camera bracket is in place, the set screws on the mounting bracket should be tightened without over-tightening. The camera cover is then installed and secured using two T-15 screws provided in the kit. The manual also notes that the camera image may appear rotated initially, but the product includes an auto-rotate feature that will adjust the image within the first 30 to 60 minutes of driving.
Electrical Wiring and Power Configuration
The FDM requires both a 12V switched ignition and a ground connection for proper operation. Users are advised to run the wiring harness to the vehicle’s fuse box and install Add-A-Fuse devices for both switched and constant power. This ensures that the mirror receives the necessary power in all driving conditions.
One user experience report from an online forum highlights the use of T-taps on the dome light wiring as an alternative to running the harness through the A-pillar. However, the user acknowledges that the Gentex engineers have designed the wiring process with specific reasons in mind, and it is advisable to follow the official installation instructions to avoid potential issues.
The wiring harness should be installed in a way that minimizes interference with the vehicle’s interior and ensures that all connections are secure. Users are encouraged to route the coax cable in a manner that tucks it out of the way and prevents any potential damage from movement or vibration.
Operational Modes and Features
The Gentex Full Display Mirror offers three primary modes of operation: Mirror Mode, Display Mode, and Reverse Mode (if equipped). Each mode serves a distinct purpose and can be activated using the toggle switch located at the base of the mirror.
Mirror Mode: In this mode, the FDM functions as a standard auto-dimming rearview mirror. Users can adjust the mirror for proper vision out of the rear window. During nighttime driving, the mirror automatically detects glare from trailing vehicle headlights and dims to the appropriate level to preserve driver vision.
Display Mode: To activate this mode, users must toggle the switch toward the driver. The mirror then illuminates an LCD display, providing a real-time, wide-angle video feed from the rearward-facing camera. This mode is particularly useful for obtaining an unobstructed view of the area behind the vehicle.
Reverse Mode: If the FDM is equipped with this feature, it will automatically switch to reverse view when the vehicle is placed in reverse. This provides an enhanced view of the area behind the vehicle, aiding in parking and maneuvering.
Users can also activate a secondary camera via an NTSC input by toggling the mirror to mirror mode and holding the farthest button to the right for 23–27 seconds. This feature is triggered by 12V to pin 8 and is useful for integrating additional cameras for expanded rear vision.
Testing and Troubleshooting
After installation, users are advised to test the auto-dimming function to ensure the mirror is operating correctly. This can be done by toggling the lever forward toward the windshield to place the mirror in mirror mode. While in this mode, a dark cloth or cardboard should be used to completely cover the forward-looking sensor. The mirror should dim after a few seconds, depending on light conditions.
If the mirror does not dim as expected, users should check for obstructions to the sensor and ensure that the wiring connections are secure. Additionally, users should verify that the mirror is properly mounted and that the camera is correctly positioned to provide an accurate and level image.
For users who have integrated the HomeLink feature, the mirror can be programmed to control garage door openers and other compatible devices. One user reported that the HomeLink feature was particularly useful for opening garage doors from a distance, enhancing convenience and safety.
User Experiences and Additional Insights
User experience reports highlight the value of the Gentex FDM, particularly in terms of the auto-dimming feature and the integration of the HomeLink functionality. One user noted that the mirror significantly improved driving comfort by reducing glare from trailing vehicles, especially during nighttime driving. The user also praised the ease of installation and the overall performance of the mirror.
Another user mentioned that while the side view mirrors were still relatively bright, the Gentex FDM provided a more comfortable and reliable rear view. The user also emphasized the affordability of the Gentex mirror, noting that it was available at a reasonable price on online marketplaces such as eBay.
Despite the generally positive feedback, some users reported minor issues, such as the brightness of the side view mirrors. However, these issues were not attributed to the FDM itself but rather to the existing vehicle design.
Conclusion
The Gentex GENFDM3LN Full Display Mirror is a versatile and advanced rear vision system that combines auto-dimming functionality with a high-quality LCD display. The installation process, while requiring some technical knowledge, is generally straightforward and well-documented in the official manual. Users are encouraged to follow the provided instructions carefully to ensure a successful installation and optimal performance.
The mirror’s operational modes—Mirror Mode, Display Mode, and Reverse Mode—offer a range of benefits depending on the driving situation. The integration of the HomeLink feature further enhances the mirror’s utility by allowing users to control garage door openers and other compatible devices.
Based on user experience reports, the Gentex FDM is a valuable addition to any vehicle, offering improved visibility, comfort, and convenience. The availability of the mirror at a reasonable price makes it an attractive option for U.S. consumers seeking to enhance their driving experience with advanced rear vision technology.