Strange Cruise Control Operation??

[mandm1]

Hello Everyone, forgive if this has been covered elsewhere; I did not see anything in a search.

I have been having a strange problem with the functionality of the cruise control and the subsequent shifting of the transmission. My dealer service dep't. claims it is normal and Land Rover corporate does, too. Here is an excerpt of the letter I sent to corporate.

... Secondly, (but of most importance), the transmission operation while using cruise control is SIMPLY NOT RIGHT!! As briefly as possible -- During normal driving (without using cruise) the transmission shifts through all six gears while attaining highway speed. When a grade is encountered, the transmission might downshift from sixth to fifth or even fourth, but then goes back to sixth soon after the terrain levels out. When using cruise control; however, it's a different story! The transmission will downshift normally when going up a grade or when passing, etc., but WILL NOT then upshift to sixth gear like it should. It will resolutely stay in fifth gear unless/until the vehicle goes DOWN a grade or we "tap down" the cruise control a couple of miles-per-hour. Only then will the transmission shift into sixth gear ...

Does anyone else have this problem? My LR3 (2006 HSE V8) does this all the time. Several times while trying to sort this out I have waited as long as 2 miles after the downshift while traveling on level ground, but the LR3 won't upshift to 6th unless I "tap-down" or go down an incline. Doesn't matter if I am in Sport mode or Normal. Doesn't matter if the LR3 is cold or has been driven for many miles and warmed up. The transmission functions fine in this regard when NOT using cruise (either in sport or normal modes.)

Also, I have the "transmission jerks when almost coming to a stop and then going" condition reported here elsewhere, but that is a separate issue I guess.

Thanks for any responses - they are much appreciated as I continue to argue with the dealer and Land Rover North America.

Mike

 

[Houm_WA]

...sounds like LR needs to put the ZF under a microscope and possibly come up with a specific fix in a new software release, if possible. This transmission-**** is ubiquitous; not sure about the CC issue, I'll have try it out.

 

[grommet]

I never use cruise control except on boring highway drives, so I have no idea. I'll need to test. So it seems to act more like when the transmission is in Sport mode?

Regarding the "hard shift", it rarely happens to me now... but I also rarely do "rolling stops." The dealer can clear the adaptive learning on the transmission... and, supposedly, if you immediately drive it hard a bit (a few fast 0-60s), it may minimize the issue.

 

[dronedog]

i've noticed mine does the same thing. it will shift down quickly but takes a long while to shift back. i have gotten so if i know there are some hills coming (or bridge because it doesn't take much) i flip it over and manually put it in 6th. the engine has plenty of power to pull me up and keep the speed. i just figure it is a product of the close ratio and six speeds. i assume the engineers were thinking about the weight of the vehicle and have it shift down early. i am not sure mine takes two miles to shift back but it does take a while or a downhill.
the dog

 

[mandm1]

Thanks guys for all of your responses,

Houm_WA - "ubiquitous" Hey!!, that's the word I was looking for! Couldn't find it in my empty skull when I posted yesterday.

grommet - I guess it acts more like the sports mode in that it is predisposed to upshift more quickly; but the fact that it is reluctant to downshift once the setpoint has been attained (even while covering flat ground) is an anomaly, IMHO. BTW, you seem to be THE guru on this and other LR forums - thanks now and in the future for all of your advice.

dronedog - I agree with you re: the weight of the vehicle and the fact that it upshifts at the slighest provocation. I just wish it shifted back into top gear by itself without requiring driver intervention. Also, "two miles" was the point at which I gave up and forced a downshift myself, rather than waiting any longer. If there is a downhill, it will downshift. If the road is flat (most are depressing flat and straight here in Iowa) the wait for a downshift could be infinite, for all I know. It will stay in 5th until ??

Thanks Again ...
Mike