9 Jun 2016

Key Fob Cannot Lock/Unlock Car Remotely


Recently, my 10-years old Chevrolet Tacuma refused to start one day. All indicating lights on the instruments panel disappeared - engine light, break light, safety warning light, even the remote key fob LCD! It's clearly that the battery is dead - I have to say it's an amazing period of service. Even the guy who replaced the battery admitted it as well. He told me that all new batteries could run about 2-5 years depending on brands. After replacing the battery, everything goes back to normal - well, at that moment!


I have tested these methods - unfortunately, NONE of the worked! However, I found the reason behind this scene by accident - my WiFi router is the culprit. Nowadays, almost all WiFi router you can get off the market has the built-in capability of selecting WiFi channels automatically if it detected any interference. Some articles said that channels 1, 6 and 11 would be the prefered ones for 2.4G network (I doubtted). I guess mine did the same initially. No too far ago, my new neighbour moved in to their house opposite the road. I assume they get a new router from their ISP at the same time as no one could live without internet in the current era. For some reason, my router thought channel 9 would be a good choice to go - NOT GOOD ENOUGH FOR MY CAR KEY FOB! It flooded my car key fob with signals that it cannot understand. So it refuses to work at all. After a thourough test I found that ONLY channel 9 has interference with the car kay fob. By selecting another channels in the router's setting, my car key fob works as before.

In the following days, I used the car occasionally. And suddenly I found the key fob didn't work as before. the central lock is ok as I can unlock the car by key. the central lock responded as expected - I can simply hear it. however, the key fob just doesn't work. Red light on it flashes as soon as I press any button - same on the spare key fob.

The first thought came to my mind is that there might be some problems with fuses, which happened to me in the other cars I owned before. By following the instruction in the user manual I pulled out all suspicious fuses to check. All are fine - no visible faulty at all.

Then I searched on some Chinese car owner forums. Different cars have different routines - not for Chevrolet. I tried to one looks more sensible to me:

1. lock all doors
2. insert key into ignitor
3. turn to position ON (or II) - the one just before starting the engine. You have to do this as quickly as possible - the rule is 4 times in 6 seconds (some others said 6 times in 10 seconds).
4. press any button on your key for 4 seconds. You'll hear a beep to indicate the re-synchronise process finishes and your key fob will function as before.

Unfortunetely, it didn't work - no matter how fast I turn the key or how long I press the button after that crazy turnning. It just didn't work. I decided to make more search on this frustrauting problem. Then some other solutions jumped out.

1. close all windows, doors, bonet, and tailgate. sit inside the car. Then get both keys and press the locking button 4 times on each key (make sure you do both keys) followed by pressing the unlock button 4 times on each key. You should find all doors will be unlocked then. 4 times locking , 4 times unlocking method.

2. If the remote fob won't work, try re-synchronising by unlocking car with key, then turn the ignition on and off, then immediately press one of the fob buttons 3 times it should now be re-synchronised. ON/OFF-button method.

Will go for a test and update this post whatever the porblem would be solved or not.

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