"Sticky" auto shifts
I have a 2001 UK import Grand Cherokee 2.7 CRD that has a small (I hope) problem.
Here in Southern UK we rarely get temperatures below freezing (32F/0C) but over the last month we have had such, and I have found that if the airtemp is below 35F the OBC light stays on, and the auto transmission refuses to change up from 1st gear. This condition exists until I've driven for about 10 minutes when, if I stop for 5 minutes or so and the engine heat 'soaks thru' the system, when everything is O.K. The colder it is, the longer this takes. Today, when the air temp was about 37F, and it did change as far as 2nd gear, I only drove about half a mile before the situation rectified itself whilst on the move.
My instant gut reaction to this problem was "....old, cold, dirty ATF....". The local auto transmission specialists say that this unlikely to be the cause of my problem, and that it is quite likely to be "....the solenoid....", (they didn't specify which one), and they want £50 plus tax (about $100) just to hook up their computer test gear and drive the car to check it out. Trouble is that I know damn well that when they get the vehicle the temp will be warm enough that the fault won't manifest itself and I'm reluctant to spend that kind of money just to be told "....we can't find anything wrong....".
On the other hand their 'gearbox service' charge is reasonable. £99 plus tax (about $170), inclusive of parts and ATF, to remove and clean pan, drain system, fit new primary filter, refit parts with new gaskets/seals etc, and re-fill. If I go this route, however, the invoice would read, "....customer advised that a service alone would not cure the problem....".
Has anybody had experience of this kind of problem? If so, what did you do to cure it?
The vehicle is now 10 years old and the mileage just under 100,000 miles. I'm pretty confident that the ATF has probably not been changed during its lifetime and would expect that it is due for a change round about now.
Any advice from experienced Jeep owners would be much appreciated.
Thanks in advance.