98 Lx470 On Cruise Drops 2 Down 2 Gears On Any Slight Hill

[Four70]

Hi

My '98 LX70 (about 88,00klms and still smelling like new inside) drives me crazy when set on cruise mode.

The problem is when it come up against a bit of a uphill grade (that in non cruise mode it would do in top gear) it drops down to 2nd

- of course the engine revs increase and the engine is damn near screaming - a quick tap on the brake etc stops that but then I have to reset the cruise mode to on.

I have been to 3 Lexus dealers who have shoved test instruments under the dash and then tell me there is no fault found - WRONG!

I have even discussed this with a Toyota dealer - tho they didn't drive the car, at least they had a 'bright' idea that there may be a problem with the detent cable ??

Has anyone else had this problem as its very unnerving and dangerous to be following someone up an easy grade to all of a sudden have your car screaming up their exhaust pipe within seconds!

All ideas/help appreciated

MikeM

[NicLX470]

It's normal behavior. There is nothing wrong with the truck. The cruise system tries to keep the set speed and when it encounters a decrease in speed due to an incline it cannot determine how steep the incline is. So it downshifts pretty hard to keep the set speed when sometimes just a little bit more gas in overdrive will work. But without eyes the computer cannot decide this. When you drive without cruise you can determine how much pedal you need to keep in a certain speed range.

[GDixon]

Unfortunately, that is how the cruise control seems to work. It does the same thing on an RX 350. That forum has a post or two about the problem but it is identical to what you are experiencing. Most folks just don't use cruise in hilly country.

The constant shifting is sudden and alarming at times.

A flash of the computer would fix all of the issues but Lexus doesn't seem to want to alter the shift points for some reason.

[xlr8it]

I have a 99 lx470 and it does the same , the only thing helps is as you approach the hill hit the overdrive button to off and that is enough for it not shift any lower.