'18 Yukon XL Key Fob/Keyless Entry Issues

[MLe132]

Help. I have a 2018 Yukon XL Denali that I bought used from a dealer 1.5 years ago. About 8 months ago the key fob started acting up.
It started with the key not being detected inside the vehicle, even when it was running, and when I'm trying to start the vehicle. The START/STOP is also sometimes unresponsive when trying to turn it off. It would give me the error message most often after my 30 minutes drive home from work and when I stop at the mailbox bank (leave the key in it, running, while I get out and grab the mail). The vehicle continues to operate as normal, despite the warning message.
I've replaced the batteries in the main key fob, replaced the main key fob entirely, and tried the secondary key with the same problems. I've had ALL the key fob relearned at the dealership 3 times, and still no fix. The mechanics also report they can't duplicate the problem. Took it to a different dealer, and the same thing.
The vehicle has also locked the key inside itself a few times.
At about the same time, the range on the keyless entry dropped to inches and is often unresponsive entirely to the thumb unlock button. The right side doors are more responsive to keyless entry than the left (the driver's side being the absolute worst), however still intermittent and extremely short range.
Thought I might be crazy, but my husband and parents all reported the same problem with the key fob.

Also around the same time at the key fob and keyless entry, my front left tire pressure sensor went out at random, intermittent intervals. It was also the front left. That took getting it relearned a few times and an ultimate replacement of the part to get it to act right.

A few months ago, I started getting a Tow/Haul error message screaming at me while I was sitting at a stop light with NO trailer and it wouldn't stop. That was also a fix the dealership was able to provide rather quickly.

Not sure if all those things tie into each other at all, but, who knows?

I'm mostly incredibly frustrated with the bonkers key fob and keyless entry. First-world problems, I know, but I didn't spend the extra on a Denali for fun...

I'm a fighter jet mechanic, so I have SOME idea of how to troubleshoot stuff and understand that not being able to duplicate the problem makes troubleshooting very difficult. But I also know that this is not normal operations (it worked fine when I first bought it!) and that there is SOMETHING that has gone bad, or is going bad, I just have NO idea what that component is. Jets are my thing, vehicles are not.

I appreciate your help and look forward to hearing from you.

 

[Blackcar]

Is this link how you programed system. https://www.programyourremote.com/c...ey-programming-instructions-listing-8476.aspx
Also has vehicle battery been checked .

 

[MLe132]

Is this link how you programed system. https://www.programyourremote.com/c...ey-programming-instructions-listing-8476.aspx
Also has vehicle battery been checked .

I did not program the keys myself, I let the dealership do that every time.
I have not gotten any indicators that the battery is having issues, either through an error message on the information center or any mechanical manifestations of a problem.
Is there something regarding the battery I should be looking for specifically?

 

[Doubeleive]

if the key fob has been replaced and you still are having the exact same problems then I would lean towards replacing the receiver module as well, yes it's a gamble and it's money out of pocket but all you have to do is take it in and just tell the service guy "customer request to change the keyless receiver module". no it wont be under warranty or anything else.
if it resolves the issue then great if not, then ask for a "deep diagnostic" this will also be out of pocket and normally a good tech can find the problem in 2-3 hours or less.
"if" there is any bumper to bumper warranty and they find the problem in the deep diagnostic and you have not added any aftermarket accessories to vehicle then that diagnostic may be covered.
the new electronic systems are very hard for anyone to "guess" or even troubleshoot anymore unless you have a scope and know how to use it and have the troubleshooting technical diagram as well.
the only thing you can do otherwise is be sure the vehicle battery is good (have it bench tested) and all the grounds are clean and snug.

 

[MLe132]

if the key fob has been replaced and you still are having the exact same problems then I would lean towards replacing the receiver module as well, yes it's a gamble and it's money out of pocket but all you have to do is take it in and just tell the service guy "customer request to change the keyless receiver module". no it wont be under warranty or anything else.
if it resolves the issue then great if not, then ask for a "deep diagnostic" this will also be out of pocket and normally a good tech can find the problem in 2-3 hours or less.
"if" there is any bumper to bumper warranty and they find the problem in the deep diagnostic and you have not added any aftermarket accessories to vehicle then that diagnostic may be covered.
the new electronic systems are very hard for anyone to "guess" or even troubleshoot anymore unless you have a scope and know how to use it and have the troubleshooting technical diagram as well.
the only thing you can do otherwise is be sure the vehicle battery is good (have it bench tested) and all the grounds are clean and snug.

Thank you! I’ll get the battery bench checked tomorrow. AutoZone I imagine would suffice for that?
How difficult is it to replace the keyless receiver module? I have no problem doing relatively easy maintenance myself. I tried to look online for a Haynes or something, but I could only find a manual in Spanish, and I don’t have those language skills.

 

[Blackcar]

I did not program the keys myself, I let the dealership do that every time.
I have not gotten any indicators that the battery is having issues, either through an error message on the information center or any mechanical manifestations of a problem.
Is there something regarding the battery I should be looking for specifically?

You say the vehicle is getting messages and strange thinks happening sometimes that points to battery or ground. If you leave fob in vehicle and close door does horn beep twice.

 

[Doubeleive]

Thank you! I’ll get the battery bench checked tomorrow. AutoZone I imagine would suffice for that?
How difficult is it to replace the keyless receiver module? I have no problem doing relatively easy maintenance myself. I tried to look online for a Haynes or something, but I could only find a manual in Spanish, and I don’t have those language skills.

changing out the module is probably not all that difficult BUT it will have to be programmed and there is no way around that. I believe the module is on the drivers side rear inside behind all the plastic trim next to the rear wheel well area (just going off of memory, I could be wrong) if it is there then the 3rd row has to some out and you have to remove a couple other rear panels to get access to it. I think it has a couple other integrated functions as well. you would need to do some googling. if you call the dealer parts department with the last 8 of your vin they can give you the part number you need to order and from there you can enter the part number online and usually there are diagrams of where it is located.

 

[MLe132]

You say the vehicle is getting messages and strange thinks happening sometimes that points to battery or ground. If you leave fob in vehicle and close door does horn beep twice.

I’m hoping battery…a quick/cheap-ish fix after this long would be great. To your point about leaving the fob in the vehicle…yes. For the most part, it does beep at me, however sometimes it doesn’t and locks itself. (Thankfully I can unlock it with my watch…but still...).

 

[MLe132]

changing out the module is probably not all that difficult BUT it will have to be programmed and there is no way around that. I believe the module is on the drivers side rear inside behind all the plastic trim next to the rear wheel well area (just going off of memory, I could be wrong) if it is there then the 3rd row has to some out and you have to remove a couple other rear panels to get access to it. I think it has a couple other integrated functions as well. you would need to do some googling. if you call the dealer parts department with the last 8 of your vin they can give you the part number you need to order and from there you can enter the part number online and usually there are diagrams of where it is located.

changing out the module is probably not all that difficult BUT it will have to be programmed and there is no way around that. I believe the module is on the drivers side rear inside behind all the plastic trim next to the rear wheel well area (just going off of memory, I could be wrong) if it is there then the 3rd row has to some out and you have to remove a couple other rear panels to get access to it. I think it has a couple other integrated functions as well. you would need to do some googling. if you call the dealer parts department with the last 8 of your vin they can give you the part number you need to order and from there you can enter the part number online and usually there are diagrams of where it is located.

Welp, that answers that! I’ll be bringing it in then, I’m not dealing with programming. I cannot thank you enough for all the insight! You’ve gotten me closer to an answer than anyone so far! I’ll update as progress is/isn’t made.

 

[Jroby42]

Welp, that answers that! I’ll be bringing it in then, I’m not dealing with programming. I cannot thank you enough for all the insight! You’ve gotten me closer to an answer than anyone so far! I’ll update as progress is/isn’t made.

Not sure if this is the module that doubeleive is referring to but this thread may help. I was having similar fob issues and replaced the antenna receiver, and fob issues resolved. No programming required. 2020 Yukon Xl, SLT and it is located passenger rear/rear hatch area, above headliner near window. Not difficult to replace. I did not have the other error messages you are experiencing. Good luck!

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