Ok. Before I go making an appointment with the dealer, how did you come to this conclusion and for what purpose do they need to have a DCM "handshake"? To be clear, I am not talking about using Enform. I had remote start via my key fob and then suddenly I didn't. Is there a reason it dropped the original "handshake"?

Is the idea that my remote was using 3G networks to start the vehicle (from 5' away)? Something tells me it was just using short range transmission of sorts, not cellular technology. I think that was related to Enform and the ability to start the vehicle from anywhere. My ability to remote start with the key fob did not disappear with the sunsetting of 3G, so I'm a bit confused here. Or maybe it didn't and I just didn't notice.

Whatever is the procedure, it should be outlined in the service manual that the dealers use, which I have. I also have Techstream. So the only thing I can think of that I probably cannot do would be anything requiring a unique code pertaining to vehicle immobilization or something tied to the car's VIN.

Edit: I'm pretty sure this can be done at home with TIS. Per the TSB you posted, the procedure is found in "THEFT DETERRENT / KEYLESS ENTRY- IMMOBILISER SYSTEM- REGISTRATION" section of the Service Manual. This procedure is outlined in the two pictures I posted in my last post. Aka, fire up TIS, navigate to "Body Electrical / Smart Access / Utility / ECU Communication ID Registration / ID code box and Steering Lock"

... and follow the on-screen prompts.

 

Am going to dig into this further when it's not so cold in my garage and I have a little more time. You can use TIS to access the Immobilizer System Data List to see what the bit is for "Wireless C Code" which I think tells you if your key fob is registered or not for remote engine start, at which point it can be flipped in either direction via the above process.

Edit: Ok, I opened TIS, navigated to "Body Electrical / Smart Access / Utility / ECU Communication ID Registration / ID code box and Steering Lock", it confirms that I'm initiating the "handshake" procedure (even used that word on the screen), confirmed it was "successful", but it did **not** restore my remote starting capabilities.

The next question is, does that mean I need to set up the key fob as new and perhaps that will fix it? To anyone that went to the dealer to have this done, did they ask you to bring in both keys? This is required or else any fobs not present will be bricked. So far the "handshake" procedure has failed and not sure what are the next steps. I did confirm that "Wireless C Code" is set to "regd" (for registered).

 

@nitroracer - I understand where you're coming from with respect to the key fob remote being just feet away. Your key fob is no longer able to remote start your car though, right?

It's my understanding that feature - to remote start your 2018 model Lexus car using the key fob - is 'wrapped-up' (semantically speaking for lack of a proper technical term) in the DCM program parameters - and the TSB handshake update of the DCM will unwrap it, and then the key fob will work again to remote start your car.

Furthermore, after the DCM is updated, if you wanted to sign-up for Lexus Enform (for $8/month) you can remote start your car using the Lexus app on your smartphone from anywhere you have cellular coverage instead of needing to be within a 100 yards or so for the key fob's RF signal to communicate with (wait for it) the DCM - that is of course after you get the DCM update that is. .

 

It's not an "update", per se. It's just a reinitialization. I just did the procedure per the TSB, onscreen said it was successful, but this did not restore my ability to remote start via the key fob.

 

@nitroracer - I had the DCM in my 2018 GS 450h updated and both my OE key fobs were then immediately able to remote start the car. Nothing needed to be done to the OE key fobs. The key fob remote start capability is wrapped-up in the programming of the car's DCM. It's my understanding the DCM must be updated for the key fob remote start capability to work.

You're lucky that your car is a 2018, otherwise the DCM cannot be updated for key fob remote start capability or to use the Lexus Enform app to remote start the car...as I understand it. Older models are simply out of luck it appears.

I really do not know what one can expect to accomplish using Techstream alone without [what I call] the special (data) program needed, which is only available from Lexus.

It's my understanding [what I call] the special (data) program must be a part of the update/reinitialization (activation) procedure. This seems to be true since your 'reinitialization' procedure per the TSB using Techstream displayed that the 'reinitialization' was successful, yet - whatever it was you may have accomplished - did not restore your ability to remote start your car via your [I assume] OE linked key fob.

I think the Lexus technician needs a special (data) program available only from Lexus (I guess downloaded from the Lexus mainframe) to use in conjunction with Techstream to perform this DCM handshake update/activation procedure. I recall when I had my car's DCM activation procedure done I was told it might take a couple hours - because they first had to download something (I assume the special data program) to use with Techstream. However, once I was informed they had started the DCM update/reinitialization (activation) procedure it only took a little over an hour to complete.

I seriously doubt this Telematics Data Communication Module (DCM) activation procedure can be accomplished using Techstream alone without [what I call] the special (data) program which I'm pretty sure is available only from Lexus...





Note: I attached the Lexus L-SB-0006-19.pdf in this post (below).

 

@nitroracer - Just a gentle forewarning - I wouldn't be messing around much with the Smart Key ID communications for your car. You most definitely do not want to 'brick' your car, making it nonfunctional or permanently disabled where you can't even open a locked door or the trunk, or perish the thought, not be able to start and drive the car.

I think some people have spent a whole lot of money for Lexus to resolve what they caused by carelessly messing around with the car's Smart Key ID communications - having unwittingly rendered their car completely and totally unusable...

 

So just an update... My car is at the dealership for service and I asked them to do the update... They are charging nearly $200 for it, an hour of labor basically... And saying there's no guarantee it will fix the remote start.
Sooo... Atleast for me, not a free update at all. I'm probably gonna pass on the update and rather invest in an aftermarket remote start which is a lot more reliable than the Lexus standard in my experience...

 

@DrunkFuX - The reason you are being charged an hour of labor is because your car is out of basic warranty and you don't have Lexus extended warranty. But beyond that, the registered owner of your 2018 4GS could have had this DCM activation Procedure [update] done back in 2019 when the Lexus Service Bulletin originally came out or anytime before the basic warranty expired. Lexus mailed the Service Bulletin to owners of record.

I know for an absolute fact the DCM Activation Procedure for a 2018 4GS will allow the remote start to work as designed (see image below of LSB) because I had it done for my 2018 GS 450h and my remote start works beautifully.

For your Lexus dealer to say there's no guarantee the DCM activation Procedure will fix the remote start is totally asinine - it was actually just plain stupid... However, I suspect that person knew it was an outright lie to tell you there was no guarantee it will fix the remote start - - or maybe it was their way of providing you an 'easy out' avenue to decline the work if you had already possibly balked unpleasantly about the one hour labor charge.

Good luck if you have an aftermarket remote start installed. I personally would never choose an aftermarket remote start over the Lexus original remote start. You deciding to invest in an aftermarket remote start instead of spending $200 to get the original Lexus remote start to work makes no sense to me... I don't see the logic in that except for your personal repudiation of the dealer because you are opposed to them needing to charge you for this procedure...

Maybe you haven't read any of the threads about people having an aftermarket remote start installed that ended up being a huge, expensive mistake such as THIS.