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My 99 RX 300 has a finicky cruise control. It will only set on an uphill grade. When set it stays solid and can be accelerated or decelerated with the cruise control lover. If you try to set it on flat ground Or a downgrade it will not set and the cruise light will flash. If you have successfully set it and hit the brake which disengages it you cannot reengage unless you are on an uphill grade. If for some reason it doesn’t set and it flashes it will never set again unless I stop the car and turn it off. It seems as though there is both a mechanical and electrical issue and I would sure appreciate some advice because it’s one thing on my car that’s hard to live without!
Most likely it is the cruise control actuator. It is both electrical and mechanical. The picture below show what it look like. It's a 20 yo car and things begin to break.
Cruise Control actuator
Believe it or not, theres a way to check cruise control DTC’s on our RX’s. Lol.
Wont cost you anything either.
Jumper wire is all you need.
Jump the 2 terminals on DLC2 (under drivers dash) then turn the key ON.
Count the blinks. Cruise light
1st blink will have a long pause after.
Example:
Blink........blink..blink......
Thats code 12
Blink........blink........
thats 11
You get the idea.
My brothers 99 had a code 11,15 - actuator motor circuit. Junkyard we went. 😂
Hope this helps.
What good news and I just happen to have a jumper wire. Can’t wait for tomorrow I’ll give it a test. Thank you so very much. I’ll bet I’m going to get the same thing your brother got.
After the pictures and finding the unit I saw that it has a simple cable mechanism that can be adjusted with 2 locking nuts that both hold the cable to the back wall and also maintain the cable adjustment. I tightened by moving the cables to the right about half an inch and now my old right (heavy) foot can rest with no fear of speeding tickets! With almost 200,000 miles it is about at the end of its adjustment travel but thanks to all of you I was able to find and repair it for now.
After the pictures and finding the unit I saw that it has a simple cable mechanism that can be adjusted with 2 locking nuts that both hold the cable to the back wall and also maintain the cable adjustment. I tightened by moving the cables to the right about half an inch and now my old right (heavy) foot can rest with no fear of speeding tickets! With almost 200,000 miles it is about at the end of its adjustment travel but thanks to all of you I was able to find and repair it for now.
Glad it is fixed. I would suggest do a bit of study on why it needed adjustment. Did the fixed position of the regulator move, or the cable stretched, or the throttle part has become loose? Cable should not stretch, if it did then it is frayed and must be replaced.
Why do I say this? There is safety issue. The mechanical (linkage) problems can cause unintended acceleration.
I’m a little surprised by the suggestion that a cable won’t stretch. Lexus put in at least 2 inches of travel for the adjustment of that cable. The car has almost 200,000 miles on it. The proof of the pudding is in the eating - when I Adjusted the cable it started to work. I’m Not opposed to replacing the assembly but I wonder why I should? I know you are very knowledgeable about Lexis I’ve seen your videos and you are the moderator here so with deference - maybe you could be a little more specific in ruling out a stretched cable when Lexus provided for the adjustment.
I’m a little surprised by the suggestion that a cable won’t stretch. Lexus put in at least 2 inches of travel for the adjustment of that cable. The car has almost 200,000 miles on it. The proof of the pudding is in the eating - when I Adjusted the cable it started to work. I’m Not opposed to replacing the assembly but I wonder why I should? I know you are very knowledgeable about Lexis I’ve seen your videos and you are the moderator here so with deference - maybe you could be a little more specific in ruling out a stretched cable when Lexus provided for the adjustment.
Thank you for very kind words but keep in mind we are all humans and I have made many mistakes. I dont think I am on any video, you may have confused with some one else. "Moderator" does not come with any special qualifications. It is a post that assigned based on need, nominations, willingness to accept and after a history with clubLexus. The group of moderators perform volunteer service and take care small issues and please do not think that as a moderator we have special technical qualifications.
First the safety part ... The cable pulls the throttle [you can see it in action once you remove the cover]. You will see a pulley which can be twisted by the accelerator cable and the other other half has the cable for the cruise control. If either of the cables does not return to no throttle, the engine will not rev down when you lift the foot from the gas pedal. Once we agree on that lets move on the adjustment part. Throttle stuck can come form the pedal and also form the cruise control side. There are horror stories about stuck throttle.
Adjustment: All manufacturers allow adjustments to accommodate difference in location of two parts and material available to link them.
Look at the history of your vehicle. If it was repaired , it is expected that a good mechanic will always mark before disassembly and set it to the same value when they put it back. If the setting is different then the cause must always be explored. That is what my advice to you was. If for many years your cruise control worked fine, why did it develop the need to adjust by a lot? Trust me the cable does not stretch by even 1/10 of in inch without some break in it.
If safety was not the issue, I would have not posted.
No, it would only Set when going up a grade. After set it would hold anywhere. If you had to set it again after hitting the brake you better wait until you were on a grade. Since adjusting it it sets just fine now on flat road although not when going downhill. I take this to mean I did not tighten it enough but I am waiting for some information on how to determine adjustment before I mess with it anymore. Read my first post it gives very good detail.
No, it would only Set when going up a grade. After set it would hold anywhere. If you had to set it again after hitting the brake you better wait until you were on a grade. Since adjusting it it sets just fine now on flat road although not when going downhill. I take this to mean I did not tighten it enough but I am waiting for some information on how to determine adjustment before I mess with it anymore. Read my first post it gives very good detail.
Before the cruise would 'set' while going uphill, now it doesn't 'set' if going downhill. The engine is moving slightly back while going up hill and slightly forward while going downhill, better check your engine mounts.
01-17-19, 08:03 PM
Cruise Control problem
