Building A Longer Range Keyless Entry Remote

[ec437]

Would this be possible for a particularly skilled electrical engineer? How does the coding work on these keys? Anyone know?

[silvermate]

i don't know.........but if you figure something our let me know. as i am interested in the same thing, my Keyless doesn't work past like 10 feet

[Shaggz]

Wouldn't it be easier, and cheaper to just replace the remote keyless entry functionality with an aftermarket unit from any electronics store? You would also get more functionality, such as trunk or window operation, as well as remote starter with a fraction of the effort. Of course, the tiny little button on that snazzy Lexus key would become obsolete, but you sure would get a lot of added value.

If you want to try to modify the original remote key, why stop at range of operability? See if you can go ahead and add 2-click or even 3-click functionality to trigger additional things like trunk, window or remote start capability. Now that would be hot!!

Definitely keep us posted on your endeavors if you try any of this.

:D

[silvermate]

Wouldn't it be easier, and cheaper to just replace the remote keyless entry functionality with an aftermarket unit from any electronics store? You would also get more functionality, such as trunk or window operation, as well as remote starter with a fraction of the effort.  Of course, the tiny little button on that snazzy Lexus key would become obsolete, but you sure would get a lot of added value.

actually no, it wouldn't be easier nor would it be cheaper

personally i don't want anything aftermarket, hardwired, as far as electronics on my car, mabye i'm a little lame but i love the OE stuff ie....head unit, anti-theft, everything.

i like the little button on the key too B)

[Shaggz]

Nothing wrong with that...a cousin of mine is the same way, if it's not OEM he doesn't want it.

But to the point mentioned:

An aftermarket unit could be bought for as little as $80 and I would expect it would be much easier to just install that rather than attempt to re-engineer the OEM unit just to get a little range boost. Obviously, that solution would require adding some sort of signal booster to the OEM unit. Is there capacity inside the thing to do that? I'm not an Electronics Engineer, I'm a Software Engineer, so maybe there's potential I'm unaware of there.

I never disliked the little button, but I hated it's unreliability. And I'm sure this is probably specific to my vehicle, but I always had to be standing right next to the vehicle and sometimes hold my mouth just right for it to work. If it was really cold or really hot outside, it might not work at all. Then I actually lost the key, problem solved.

I am considering an aftermarket unit, simply for the purpose of regaining, as well as adding functionality. If I still had my original key, I would also be interested in a distance boost, but that's not really an option for me.

[lexs400]

It will be easier because all you'll have to do is wait an hour while it gets installed. for 179 these days you can have a remote start, door lock/unlock and all the other key features with two long range remotes (approx 500 feet) installed that includes labor.

why bother with the re-engineering of the original key. especially when you mentioned that you like everything in it's original format. why "change" the original schematics of the key remote ? :) just kiddding.

good luck with the endevour. I am sure the key range can be increased but would require ateast an antenna inside the car, and perhaps a chip with increased range inside the key. But it will end up costing more because the key as it is right now has limited space inside it therefore the aftermarket chip would have to be very tiny.

[wwest]

If you press the key edge firmly into the bottom of your chin while pressing a button the range will be extended by about 2X. Your body acts as a huge transmitting antenna.

[914lps]

I have a 91 and the remote on mine is worthless I do not use it any more. I have replaced batteries. Even spent the bucks on a new one and so on, but at best it only works 50% of the time and then I have to be close enough to the door that I can just put the key in, and stop hiting the bottun over and over agian.

[silvermate]

yeah that little button just sucks as far as performance, and reliablity, i like it though. just wish it was more efficient.

i would never take my car to an audio/alarm place for them to work on it......if i'm gonna do something i'll do it myself.....

i'll research unit and the wiring diagrams and schematics and do it myslef, that way i know its done right.......i just dont trust people to work on my car anymore, but thats just me........the only way i'll take it in is if there is no way i can do it myself, i'm an Avid diyer, and pride myself on it. but once again, thats just me and my opinion

but anywho, whatever floats your boat

yeah that chin idea is what i always do, its seems to work, don't know why though, i have no metal plates in my head, or even any fillings............

[Shaggz]

I'm with you Silvermate, I do all I can myself.

I've had too many mis-diagnosed problems by both Lexus dealers and Lexus specialty shops. No offense to any Lexus employees out there, but in my experience, they're all just money hungry jerks that don't really care if they solve your problem or not, as long as you spend money with them.

Some examples...

1. Lexus specialist stated my power window motor was bad, charged my wife $80 to tell her that. I went through the trouble of replacing the motor myself, only to discover there was nothing wrong with it! The problem was obviously the switch and a quick check with a Volts meter confirmed that. I found a scrapped switch for about $40 (maybe less), replaced it myself and it's worked perfectly for the past year or so.

2. Lexus dealer stated my fan clutch was making a lot of noise, but at the time the bulk of my problem was the power steering pump and pressure hose. After replacing the p/s pump, air control valve and pressure hose myself, my fan pulley locked up and broke my new belt. Upon inspection I discoverd the fan bracket assembly completely seized up, bad bearings. Upon inspection, I noticed metal shavings all over the area around my fan which clearly confirms bearing breakdown inside the fan bracket. I got the fan bracket from the dealer for $240 and it's all working lovely now.

3. Lexus specialist tried to convince me the brakes should be serviced by a professional because they are not like normal brakes and "special care" should be taken to see that they're done correctly. This is just plain nonsense, as the brakes on my LS400 are by far easier to service than any other vehicle I've ever owned!

I definitely would not allow some kid at a car audio shop to install a remote keyless entry system on my LS, those things come with instructions for crying out loud!!

I just wish I had known about the "chintennae" before I lost my original key.

B)

[ec437]

I wasn't thinking about enhancing the current key, instead I was wondering about building an entirely new device that functioned the same way, but had a much longer range. I know some electrical engineers that specialize in building radio frequency circuitry that might be able to help me. Does anybody have any idea what the transmitter codes are, or is this information still under lock and key by lexus? Even with a code grabber it would likely be very hard to figure out how the system works if it rotates codes every time you lock/unlock the doors. Does anyone know if the first gen keyless entry transmitters are each programmed with a single, unique, non-changing code, or do they have a dynamic system where the code changes every time the transmitter is used?

[wwest]

As of 92 Lexus added an RF choke, inductor, inline to the rear window heater and that apparently helped matters a lot.

[silvermate]

I wasn't thinking about enhancing the current key, instead I was wondering about building an entirely new device that functioned the same way, but had a much longer range. I know some electrical engineers that specialize in building radio frequency circuitry that might be able to help me. Does anybody have any idea what the transmitter codes are, or is this information still under lock and key by lexus? Even with a code grabber it would likely be very hard to figure out how the system works if it rotates codes every time you lock/unlock the doors. Does anyone know if the first gen keyless entry transmitters are each programmed with a single, unique, non-changing code, or do they have a dynamic system where the code changes every time the transmitter is used?

definately keep me posted if you find anything out. i am really interested in the same upgrade you are.

[pachocco1]

Here is a copy of a TSB for wireless keys and fobs.

lel00396.pdf

[lexus400]

someone posted about holding the key up to your chin and the results of doing that are pretty amazing. It more than doubles the range from what I can tell. Give that a try.

Bob