2005 4Runner Uphill Cruise Control Problem

[kent777]

PROBLEM: CRUISE CONTROL WILL NOT HOLD SPEED ON UPHILL GRADES.

Starting uphill, the car’s speed drops 2-3 mph below the cruise control set speed then, passing gear engages abruptly, (from approximately 2,200, up to 3,500-5,000 rpm), until speed is 3-5 mph above set speed then, the passing gear disengages and the speed immediately begins to deteriorate. This whole process can and does repeat itself multiple times depending on the length and percent of the grade, until the end of the grade. Sometimes, the car will remain in passing gear until the end of the grade. Rarely, on shallow, short grades, the cruise control will work normally, without a speed drop, or engaging the passing gear.

Every hill is an adventure! Downhill, the speed is maintained correctly. Flat and level is OK, too. But uphill, it’s kind of like a "bumper car" ride at an amusement park where you never know when someone will bump you from behind.

The Toyota dealer informed me 10,000 miles ago that the computer just needs time to learn. After 2,000 miles through the Smokey mountains recently, I've concluded my car is a moron. I did not go all 2,000 miles with cruise control engaged because constantly going into and out of passing gear is bad for engines and fuel mileage, not to mention the driver. But I did give the cruise control more than ample opportunities to work, correctly. It would not. At least it is consistently bad. Also, this system is unsafe as the cruise control suddenly kicks into passing gear like it was "floored", and will not always respond to a "cancel" command when it is in the middle of its acceleration gyration.

To make sure the car was capable of holding a speed, I turned off the cruise control and manually manipulated the accelerator. I was able to maintain 70 mph at a steady 2,200+/- rpm up a 3 mile, 6% grade with minimum effort, plus other, similar successes. The 4.7L engine has more than enough torque to maintain a constant speed without using the passing gear if the throttle is manipulated correctly by the cruise control.

The Toyota dealer maintains there is no problem, and the system is too complicated to fix, anyway. This is nonsense. I have a 2001 Tundra and its cruise control maintains speed correctly by responding to any changes in terrain promptly and gently within +/- 1 mph, without having to use the passing gear.

I only have one more year of warranty left, and I want to get this thing fixed!

Note: With the cruise control off, at higher (approximately 50+ mph) speeds, it is sometimes hard to get the car to start accelerating with only a gentle push to the accelerator pedal. You occasionally have to punch it to get it going, just like the linkage(?) was sticking.

[Brian R.]

Welcome to the AF!

The two trucks have different transmissions, and possibly different differential gears. If the Tundra is not AWD, as the 4Runner is, then that is an added drain on the 4Runner engine. This may make your comparison invalid. I don't know the facts on your trucks without alot of digging. I would find out what you can about these important factors before using this analogy with a Dealer to prove your point.

I would find a Dealer that can determine if the C/C actuator is operating correctly and not binding either internally or in the external cable.

[kent777]

The differences in transmissions aside, the main point is Toyota is technically sophisticated enough to design a cruise control that works. Apparently this is not the case because at TundraSolutions.com I found that I am not alone, it is a chronic problem over the years with various models. So, Toyota needs to get out of the denial phase and bring their cruise controls up to the same standard of reliability that the rest of their designs have earned. Besides, the way the CC behaves now, it is a safety issue.