Hi, i just bought a 2007 GX 470.
i like to use cruise control when driving up hill. i set it between 65-70 MPH but i notice it is not smooth, the RPM went from 2500 to 3500, and back to 2500 and than up to 3500, happen almost every 5 second until the road level out. just not the same as my RX 300.
please let me know if anyone have this problem.

 

I think this is normal since I notice something similar. It's not jarring, but it does search for the right RPM a lot.

 

That is normal but i think that it is bad for the engine, since it downshifts really low and then it guns it and then it stays there until you get over the hill and go for a little longer until it shifts back into its normal gear. When i'm driving by myself, i set the cruise around 70 or 75, that way it doesn't downshift going up hills but if the hill is too big i turn it off and keep my speed until i pass the hill. If my family is with me, and if i choose to use cruise control, i have to set it for 80 if not higher. I believe that this happens because of the weight at the speed that its going, its not going to pull the gx up the hill so it downshifts.

 

I use cruise control very infrequently; I used it the other day and was surprised that the vehicle went into NASCAR mode and down-shifted and gunned it everytime I hit resume.... I could understand this if I had lost 10MPH or something, but most of the time, I was only off a couple of MPH from where I had been set, and each time it downshifted (often two gears) and punched it, blowing past my setting, and then slowing back down to it... it was annoying because A) I don't drive cars like that and, B) I felt like I was being a jerk, blowing past people once I got around them... I ended up driving back above my set speed and slowing down, hitting resume, and letting the car gracefully return to the set speed... I wonder if this is related to the OPs "hunting" issue...

 

HI,
The cruise control seem to work normal on my rx 300, 2008 Nissan Armada, and Nissan Titan. the speed i usually set is 70 MPH before heading up the hills and its stay at 70 MHP without changing gear/downshift/upshift. they all drive like its on even road, none reacted like the GX 470. should we brought this matter to lexus?

One thing, California speed limits is 65, going 70 is pushing it. 80 MPH ticket!!!!! :-)

 

My GX does the samething, the transmission needs a grade logic controller.

 

My dad has a 2007 nissan titan and yes i have to agree, cruise control works frawlessly on that thing. It doesn't downshift and i don't know if you notice but when i'm doing hill, it'll put itself in neutral and then it'll go back into gear. it doesn't do that too often, only when it senses that downhill to be too steep. I guess its because it has a way bigger engine then our gx? But I've also got a friend that has a toyota tacoma, 2006 with the 4.0 and he tells me that it is doing the same thing but it is downshifting two gears instead of just one. I gave him the *shrugs*

 

I had the same problem on a road near me...set to 35mph, the GX would double down shift and surge every time I went on the road that had a sudden uphill grade...for about 10 or 15 times. Then it started working like it should have. Does this thing have an 'intelligent' system that learns after a while?

 

I took my GX on I-70 through Eisenhower tunnel in Colorado. The approach to the tunnel is very steep. Cruise control would go all apes**t. The only way to appease it, was to downshift to 3rd and leave it there. As long as you put the tranny in a low enough gear for the hill it will stay there. I guess the engine is not producing enough torque in the lower RPM range to pull the car up the hill, cruise control computer sees the speed going down - depending on the rate of speed decline - it will downshift one or two gears. Even on the smaller hills in Colorado it would hunt for the right gear. Really, really annoying, especially since you use the cruise so the car can "cruise" nice-n-easy. But, I drove a lot of different cars and they all do it. It all depends on the engines ability to produce appropriate torque for the rate of ascent and the distance of the climb. Once the speed starts folling off, cruise has no choice but to increase RPM, and that often equals downshift. Think about what happens when you start pressing on the gas. If you continue depressing the gas pedal, eventually the car will downshift one, two or even three gears. Some cars have a "slower" logic in their cruise computers, that means they will downshift once - stay there for few seconds - if not enough - downshift again. Take any car into the Rockies and I'll bet the cruise will leave you p*ssed-off.

Just my 1 1/2 cents. ;-) can't afford 2.