If the light on the rear camera isn't turning on, there are a few troubleshooting steps. Before unplugging and checking the coaxial cable, first do a power cycle on the device. To do so, unplug the power cable and wait for the lights to turn off, wait 15-20 seconds, and then power back on and see if the rear camera light does come on.
If this still doesn't work do a format on the card through your computer and if possible test the unit with the original BlackVue 16GB card. For 32GB and lower cards, format to FAT32, this will erase all the files on the card so be sure to save any video files you need before formatting. A newly formatted card will trigger a re-initialization when you plug it into a camera and power it on which may also correct the issue.
Lastly, you can look into a firmware update but be sure to do so on the computer/browser rather than over-the-air through your smartphone. Smartphone firmware updates are prone to cause issues on dash cams and we recommend against doing so.
If you've already done these 3 troubleshooting steps (power cycle, format, firmware update), you can begin to take a look at the coaxial cable connections. One common cause of a malfunctioning rear camera on 2-Channel BlackVue devices such as the DR650GW-2CH and DR750LW-2CH is a broken or bent coaxial cable. This can occur during installation if the cable is plugged into the camera port at an angle which is why we often recommend professional installation for 2-Channel devices.
The reason we recommend doing this troubleshooting step AFTER you've exhausted all other options is that the risk of physically damaging the components will increase every time you unplug/plug in the coaxial cable. A broken cable is considered physical damage and can't be covered under warranty, in the example below the cable pin is bent to the side when it should be running straight down the middle. In our customer's experience, bent pins can sometimes be pulled back into position with a bobby pin but do so at your own risk. If the pin is missing altogether that means it's already broken off and a replacement cable is needed.
If the cable has been plugged in at an angle and the pin has bent or snapped off, it's important to also check the female port of the camera and make sure the female end is not bent or mangled. If the female port is damaged and you plug in a brand new cable, you run the risk of damaging that new cable as well. Please contact us by email at email@example.com with your order number and pictures of both front and rear female coaxial ports of your dash cam before ordering a new cable and we will try to get you a replacement camera as well.