Here is a little story about a situation with our 97 ls400.
First off, the cruise didn't work when we bought our LS. When the cruise was set it would continue to accelerate until it would go about 5 miles an hour past the set speed then it would shut off and the cruise light would blink on and off. It would reset itself after turning the car off, only to do the same exact thing after engaging the cruise control.
We took the car to the Chandler Toyota in Chandler Arizona to have the timing belt and the water pump changed, and I asked the service manager, Gabe, to check the cruise control out to see what the problem was, and if it wasn't too expensive we would have the cruise control fixed also, I got a call from Gabe and he said that the car was ready to be picked up. I asked him about the cruise control problem and he said that his tech did some testing on the cruise control and it was the cruise control lever on the steering wheel. He said that the part, the lever assemble was 2000.00, and 70.00 to put it in. Yes, that was not a typo, it was 2000.00 and 70.00 to put it in. Now, how many of you would have forked over 2070.00 plus tax. Not me, no frick'in way. Not for a car that we paid 10,000 for.
Because I suffer from OCD, Ha! only halfway kidding! I bought myself a Lexus ls400 service manual off ebay and I began to study it and researched how to test the cruise control system. I don't have a fancy OBD II tester but was able to use the jumper wire and get the dtc codes. The code was 14, the cruise control actuator!!! First thing that they suggested was to make sure that the actuator cable was not loose. Guess what, my actuator cable was loose, very loose, as a matter of fact it was so loose that I am amazed that it ever worked.
Now one of the main reasons that I am writing this on this website is that when I was searching this topic there was nothing that exactly duplicated this problem and if I help just one person with a cruise control problem like this, it would be worth it. I get really upset when there is something wrong with my Lexus and people start throwing out very large quotes to fix something that is wrong with it. Lexus service managers and mechanics like to say errogant stuff like, if you have to ask how much then you probably can't afford to fix it. That is major BS. I feel the urge to knock there teeth in and I am a peaceful man. Where did the errogance come from with Lexus. It is a very nice car don't get me wrong, but it is not a Rolls Royce, for crying out loud. Lets kick it down a couple of notches.
Anyway, that is my story and I am hoping that my cruise continues to work trouble free. Good luck my Lexus friends and I hope that you can keep your cars going without breaking the bank.
I have one more problem to figure out with the car and that is the tilt steering. Mine sometimes doesn't work going up and down. Works fine in and out. If anybody has any threads on that subject let me know. Thanks.