Verifying Operation: What is causing the range between the remote and the vehicle to decrease?
First try moving the location of the receiver. The antenna wire must not be attached to a metallic surface. Zip tying the antenna wire to the vehicles metal frame will greatly reduce range. External radio frequency interference commonly found in cities such as power lines can also reduce range. If the unit worked fine, but now has decrease range, try changing the batteries in the remote control. The remote control is similar to a car alarm remote, the older the battery gets the closer you need to be to the vehicle to activate the RES. Always test range before each use of the vehicle.
