Strange behaviour 5 speed AT in 120 GXL

[rorza Member Find all posts View Profile Close rorza]

On my recent camping trip and even on many early morning roads trips I have noticed some odd AT behaviour.

It is my understanding that the AT won't change up to 5th gear until it has hit a certain temp (which seems illogical to me given that holding fourth increases revs a reasonable amount at 90km/h plus) around 65° from memory.

On my most recent camping trip my AT held fourth at 110km/h (3k revs) on level ground for almost two hours! My scangauge was reading AT temp=85°-90° (code manually entered from scangauge thread on PP) for the majority of that time and cruise control would not activate (I'm guessing it is linked to the use of 5th somehow). Is it in anyway related to the water temp for optimal cooling purposes because I noticed it would engage 5th once water temp hit 90°?

This is incredibly frustrating when you're on a long distance road trip and you are chewing through fuel like nothing else. A mates GXL 120 5 speed AT has no dramas initialising cruise control straight away with no warm up.

What exactly is going on with my rig? I have tried all sorts of little tricks to try and get it to engage 5th earlier but nothing has worked. Is it a possible software error?

Any ideas?

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

I know when towing, which I do a lot, that it is sometimes reluctant to select 5th, pushing the shift lever over to 4 and then back into D will often convince it to shift into 5th.

I don't think water temp will have any effect on it shifting into 5th, certainly doesn't with mine.

If its not changing into 5th at all, I would wonder if there is something wrong in the system that makes it think its in low range, as they wont select 5th in low range, which is actually a real PITA, but that's another story.

I guess the obvious first question is what's your trans fluid like? Getting that replaced if its a bit ordinary might be a good stating point.

Cheers Andrew

[rorza Member Find all posts View Profile Close rorza]

Not sure on trans fluid quality. I plan to install a trans cooler in the very near future and will have a full flush of the trans done at the same time as the car is at 105k mark.

I wouldn't have thought it was thinking low range was engaged if it then eventually engages 5th but stranger things have happened. I have tried the over to 4 then back to D trick to no avail.

Will start with trans fluid change, hopefully it isn't car brain related.

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

The low range thing was just a thought, highly unlikely I know, but once computers get involved anything can happen

Cheers Andrew

[joel231 Find all posts View Profile Close joel231]

could have a faulty solenoid. you may need to hook a scan tool up to the car to check it, probably the only way to tell.

Cheers Joel