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How To Test Keyless Entry Remote

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Nowadays, most car manufacturers offer a remote keyless entry (RKE) system as a standard or add-on feature for new vehicles. Because of the RKE's convenience, many car owners get frustrated when it malfunctions.  We've compiled some information to help you test your keyless entry remote.

Testing the RKE system is best done through the process of elimination.  To do this, we need to isolate and test the following items:

  1. Transmitter
  2. Receiver
  3. The car component that you are controlling remotely

Are you having problems with your car's RKE?  Alternatively, are you curious about how your RKE system works?  Read on, and we will do our best to help you understand more about this convenient feature of your car.

Remote car key car interior, How To Test Keyless Entry Remote

How Do You Test A Key Fob Transmitter?

Use Your Spare Key Fob To Test

The easiest way to test your car's key fob is to use your spare key fob.  New cars typically come with two key fobs straight out of a dealership. If your spare key fob works on your car as intended, then you immediately know that your primary key fob has problems.

Check If Your Key Fob Is Transmitting

In order to check if your key fob is transmitting, you can use a portable radio frequency remote tester.  Watch the video below to see how a remote tester works for key fobs.

Aside from confirming whether your key fob is transmitting or not, the remote tester also indicates the signal frequency of your key fob.  

Check out this remote tester on Amazon.

Use Your Television

If you know the frequency of your key fob transmitter, then you can use your Smart Television to check if your fob is indeed transmitting.  See the video below for some quick tips using this Smart TV method.

Below are the steps in using your Smart TV to test your key fob transmitter, as shown in the video above.

  1. Bring your key fob and turn on your Smart TV.
  2. On your TV, go to Settings > Tuning > Manual Store > Search
  3. Under "Search," select the frequency of your key fob transmitter.  
  4. Once the frequency is set, test your key fob by pressing each fob button.
  5. Each button pressed on the key fob should disrupt your TV screen.

If you have a Smart TV nearby and know your key fob's frequency, then this method is free and easy. As another free tip, key fobs in the U.S. and Japan use a frequency of 315 MHz, while those in Europe use 433.92 MHz.

Interpret Your Results

If you used any of the methods above, it's now time to start interpreting your results and isolating your key fob's problem.

  1. If all buttons in your key fob are transmitting, but your car is not responding to any button commands:
    • Your key fob needs resetting or reprogramming, or
    • Your car's RKE module and/or body control module (BCM) are malfunctioning, or
    • Some of your car's fuses have blown
    • Your car battery is completely discharged
  2. If all the key fob buttons are transmitting weakly or intermittently, then you may need to replace the key fob's battery.
  3. If all the key fob buttons are transmitting, but your car only responds to some of the button commands:
    • Your key fob needs resetting or reprogramming, or
    • Your RKE module and/or BCM are malfunctioning, or
    • Some of your car's electromechanical parts (e.g., power locks, alarm, tailgate, tire pressure monitor, etc.) may be malfunctioning.
  4. If only some of the key fob buttons are transmitting but your car is responding accordingly to the transmitting button's commands:
    • Some of your key fob buttons may be dirty or damaged, or
    • Some areas of your key fob's circuit board might be dirty
  5. In case none of your key fob buttons are transmitting,
    • Your key fob's battery is completely discharged, or
    • Your key fob's RFID transmitter is not functioning, or
    • The key fob's circuit board is very dirty, or
    • The key fob needs to be replaced

How Do You Fix A Remote Keyless Entry System?

closeup shot of a start car key in a male hand

The average car owner may not find it easy to fix problems with the RKE module, the BCM, the electromechanical car parts, or even the fuse box.  In such cases, it is best to seek help from the dealership or other automotive service professionals.

On the other hand, many key fob problems are easy to fix, even at home.  More often than not, your keyless entry system's problem lies in your key fob.  The most common key fob problem is a discharged battery.

Below are some key fob problems that you can fix yourself.

Discharged Or Dead Key Fob Batteries

Changing key fob batteries is quite easy.  You only need a screwdriver, a new battery, and a little finger dexterity.  Of course, checking your car's manual for step-by-step instructions won't hurt either.

Car key fobs typically use coin-type batteries like the CR2450 or the smaller CR2302.  

Fob Needs Resetting Or Reprogramming

Many modern key fobs require resetting or reprogramming after battery replacement.  Fortunately, some manufacturers made their key fobs self-programmable for owners.

Here are the steps for reprogramming key fobs for some cars with the keyless (Start/Stop button) ignition feature.  

  1. Get in your car with the key fob and close all the doors.
  2. Without stepping on the brakes, push the engine start button until it is in "Run" mode.
  3. Wait for the car's electronic hums and beeps to stop.
  4. Press and hold the "Unlock" button on your key fob for 10 seconds
  5. In a smooth sequence, release the "Unlock" button and then press and release the "Panic" key.
  6. Wait for another electronic beeping sound from your car
  7. Press the button(s) that you need to reprogram.
  8. Turn your car off to end the programming mode.
  9. Exit your car, and close all doors.
  10. Test your newly-programmed or reprogrammed key fob.

The steps may be similar but not exactly the same for your car, so always consult your car's manual.

Dirt and/or Moisture

Car key fobs often go through a significant amount of abuse.  They get squeezed inside pockets and bags, jingle and bang against the steering column, fall to the ground, or even get very dirty and wet once in a while.  

Check out this simple tutorial video on cleaning your key fob's circuit board.

Minor Physical Damage

If cleaning is not enough for your key fob to function, then you might want to check for and repair minor physical damage.

Some common key fob damage is cracked buttons, loose contact points, worn rubber buttons, or dislodged battery terminals.  You may try using adhesives for the plastics, solder for the metals, and some cleaning and flexing for the rubber parts.

What Is A Remote Keyless Entry System?

Closeup of a man's hand pushing unlock button on car remote

In today's automotive industry, your key does a lot more than unlocking the door and starting the engine.  The modern RKE system is a radio frequency-based technology that allows a user to remotely control various vehicle functions.  

An RKE system has two main components:  the transmitter (the key fob) and the receiver (the RKE module).

The Key Fob Transmitter

Set of a remote car keys isolated on a white background

A key fob contains an RFID transmitter that can send distinct commands to the car's RFID receiver to perform specific functions.  Many key fobs also contain passive RFID chips for additional functions.

The active RFID transmitter uses your key fob's battery for power, but the passive RFID chip doesn't need any juice.  

Key Fob Basic Functions

The key fob's basic functions are:

  • Lock/unlock the car doors 
  • Arm/disarm or trigger the vehicle's alarm system.
  • Open the tailgate or trunk

Other high-end key fobs have dedicated buttons for remote engine starting and stopping.

Finally, most key fobs also have mechanical keys inside the fob's housing.  This key can lock and unlock the car doors in case the fob or the car's battery gets discharged. 

Key Fob Advanced Functions

Many modern car key fobs have smart key functions that only require the key fob and the car to be within a specific distance from each other.  Among these "passive" functions are:

  • Automatic keyless entry 
  • Driver comfort settings 
  • Keyless start/stop
  • Engine immobilizer 

Some special functions need some sequence or combination of key fob buttons, like:

  • Folding Side Mirrors 
  • Remote Parking 
  • Remote Window Control

The RKE and BCM Modules

Your key fob has a partner inside your car, and this is the RKE module.  This module receives the commands from the key fob.  Your RKE module, in turn, relays all these commands to your car's body control module (BCM).

The BCM is another component that monitors and controls specific electromechanical functions of a vehicle, e.g. power windows, central locking, climate control, engine immobilizer, tire pressure monitor, etc.

The RKE and BCM modules have different installation locations depending on the car model, but it is usually hidden under the dashboard.  Because these modules are typically installed inside the vehicle, they typically do not malfunction as easily as the key fob does.

As mentioned previously, both the RKE and BCM Modules are not easy to test or diagnose.  Automotive service professionals and some enthusiasts can test the modules using the appropriate onboard diagnostics (OBD) scan tool.  Alternatively, you can go to your car's dealership for servicing.  

Wrapping Up

Hand presses unlock on the car remote control.

Although it is not easy to test the entire remote keyless entry system, the key fob by itself is easy to test.  For instance, you may purchase a remote tester online or simply use your Smart TV at home.  

The most important points after testing are the proper interpretation of the result and the isolation of the problem. 

Thank you very much for reading through.  We hope that we were able to help you understand more about your car's remote keyless entry system.

For more informative articles about RKE systems and other automotive topics, check out these great articles:

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