The cruise control on my IS350 RWD has stopped working. Cruise control light doesn't come on either when I hit the button. I did try looking for the fuse, couldn't find one. No warning lights of any kind. Is there anything else I can check before heading to the dealer?

 

There Cruise Control doesn't have a fuse as the switch is wired directly to the Engine ECU.
Basically the Cruise Control functions are housed within the ECU and the steering wheel switch is an input device to tell the ECU what to do.

Here's a few questions to narrow down what it might be:

1. When you turn the ignition on (2 presses of the Start button - no foot on brake), do you see the Check Engine light and Cruise control light on the dash briefly?
2. Which Cruise Control system do you have? Dynamic Cruise or just regular...Dynamic Cruise is the one where you can set the distance your car stays behind the car in front of you, it also has the radar sensor behind the front grill emblem
3. Was there anything that happened prior to you noticing the cruise stopped working?

If you go to the dealer, the Service Advisor will likely ask you question 3 above when checking the vehicle in for service.
The tech will then confirm question 2 and then 1...at which point if the light isn't working they will get the Techstream out to check for codes, and active test the Cruise light to see if it works, and also confirm on the data list that when you operate the Cruise switch the vehicle is seeing the appropriate input signal.

 

1. No, cruise light does not come on briefly. That was my first thought "ok maybe the light is out, let me try using it without the light" It didn't work. Cruise control would still work even if the light is out correct??
2. Regular its a 2014
3. Normal day went to work using it in the morning, on my way back from work in the evening, it didn't work.

 

It kinda sounds like the issue is just the Cruise switch itself...but without the Techstream software to confirm the switch signals are being received by the ECU it's just a guess.
It could simply be that the On/Off portion of the switch has failed, but the rest of the switch is fine. But since you can't turn it on, there's no way to know without being able to see the signals.
I think you're going to end up at the dealer.
When you checked the dash lights, the Check Engine light did come on when you turned the ignition on?

 

It was the switch, charged me $200 just to tell me that. They want $480 to replace it, not paying that. Could you please find the part number for it? Im going to either do it myself or have a shop do it.

 

Part number 84632-0E010 is for the regular cruise...it's about $100.

 

Thank you, it looks like no one ever had one of these go bad on a lexus, everything on youtube how to do it are on old toyotas.

 

I think you are the first to report a cruise switch issue.
Personally I rarely have the opportunity to use cruise as I live just outside of a major city centre...so traffic is bad, roads are crazy...every possible thing you can imagine to make you not use cruise is present.
To replace the switch is actually pretty easy depending on your comfort level and tools.
Basically you disconnect the battery, remove the driver's horn pad/airbag, and the switch is right there...just 2 screws holding it on.
I've attached the instructions...I can't stress this enough, as you have to remove the airbag...only do it yourself if you are comfortable.
In looking at the attached instructions, while they want you to completely remove the airbag, I suspect you can simply unbolt it and lay it gently on you something on you lap, like a box or pillow.
Then you can charge the cruise switch and just put the airbag back without removing the actual electrical connectors.

 

Thank you so much sasnuke. It was a 10 minute job.

For anyone that needs to do this in the future. Its simple process to get the horn/airbag out. I followed these 2 videos and sasnuke's instructions to get the Horn/Airbbag out.

Videos:

BEFORE YOU START, REMEMBER TO REMOVE THE NEGATIVE BATTERY TERMINAL. You don't need to remove the air bag wires or any wires, put the airbag/horn at top to get it out of the way. There are only 2 screws holding the switch, unplug it and put the new switch in.

 

Glad I found your post, I have exactly the same issue on my 2016 IS200T FSport. This is very unusual and I will open a case since I believe the switch became intermittent and is a Safety Hazard.

I noticed Mine wasnt working yesterday. Then I found out it only turned on when the drive wheel wasn’t straight. Then today was only working when the car was in a full stop, now Im heading out of work and is not turning on at all.

 

Just curious how you could tie the Cruise Control switch into being a Safety Hazard? By default it's a system that is Off when the vehicle is turned on.
Also the issue is not about when the Cruise is operating...more so about turning it On.
Based on the bold portion of your post, I would say the issue is the Spiral Cable and not the actual Cruise switch.

 

The same way it doesn’t want to turn On, when it does, it doesn’t want to turn Off, thats how it behaved today while driving home. Who guarantees is only the On/Off switch and not something else like a signal randomly behaving in the ECU? IMO needs to be investigated

 

The switch at the end of the Cruise stalk is the Master On/Off switch...just because it's on it doesn't mean you have to Set a speed.
You could drive around with the Master switch On indefinitely and the car would function the same...without posing a safety issue.
Also, if you did Set a speed and the Master Switch wouldn't turn off, then just tap the brake pedal...that will cancel the Set speed.

Of the thousands of IS's sold since 2014 til today, that have the same Cruise switch and Spiral Cable, you are the second person to post about this issue.
While I agree that the issue should be inspected and diagnosed as to the cause, as the system should function as designed and intended, to leap all the way to a safety concern is a little bit of a stretch...that's all I'm saying.
If you do have the dealer check, please post back with their findings...I'm sure we'd all like to know what caused this.

The ECU that the Cruise switch is sending signals to is the Main Body ECU, not the Engine ECU, so the car isn't going to do anything crazy or unexpected.

 

Wanted to share the latest on my case; the problem was not the cruise control lever, a fee weeks after not only the lever stopped working but also did all the buttons on the steering wheel. The clock spring was the culprit. Luckily the airbag light never came on, but certainly everything else wasn’t working. Bought the part and replaced it myself in 30 min. Everything is working again.

Left side old clock spring.

 

Thanks for updating the thread as to what you found to be the cause.
I would note that the old Spiral Cable (Clock Spring) in your photo does not look OEM.
The first indicator is the wire loom color...as per the one you installed, the loom is always Yellow for Airbag wires (this distinguishes them from the other harnesses in the vehicle)...on the old one it appears orange to me in the photo.
Typically orange loom is reserved for high voltage wires, as found in hybrid and electric vehicles.
And secondly is the molding of the front of the Spiral Cable...while the markings look very similar to the OEM one, and in the correct locations, you can tell they are completely different.