No codes? I hate it when that happens! Do you have the same problem with the transmission in the sport mode?

The first thing I would do is get the history of repairs from Jaguar. In a few situations they (Jaguar) would not release the information and in that case I would take a pen and pad and ask specific questions on what has been done on the car. I would then ask what the drive-train warranty is and see if this car falls into that window. I think it is 5 yrs 50,000mi but if it has been looked at it may still be covered.

It is possible that the torque converter is the problem but with no codes it is hard to say. The TCM could be part of the problem as well but at this point it is hard to say but I can say this today’s transmissions are not like the ones years ago. Today computers (control modules) make it do what it is suppose to do and if one has a hiccup well it becomes a pain in the butt.

Take the time and gather a little history on the car then move forward.

 

I think the TC issue generally doesn't set codes (or they're in the TCM, which isn't readable with ordinary OBD tools).

It's also possible that the trans is being marginally confused by a minor engine problem. It's almost free to get an OBD tool with live data and put time & effort in to see if the data show anything odd but not yet bad enough to set codes. An example would be where you've not had the battery off recently but instead of P1111 all you have is P1000 and then you'd have a problem for sure...

Backing the odds, it'll be the problem others have had, of course.

 

Thanks for the heads up on resetting the TCM.

It does still have this behavior even when I manually downshift into 5th and while at speed.

By "Merc 5" I actually mean Mercon V.

When I talked to the mechanic, he said he had to drop the rear end of the transmission to access the fill port. I don't know how he determined that it was low but I suspect he just looked in the hole(?)

 

I'll see what I can get for history on the car. Sound advice. Thanks Gus.

Not sure if it also happens in sport mode but will check after work today and let you know.

I bought it about a month ago and I think it's still under the lemon law for another 30 days. If it is the transmission, that should be covered. Right?

 

You should NOT need to lower the transmission to access the fill port. It is tight but doable. Plus it shows he does NOT understand what must be done!!

The transmission MUST be level and the fluid at the proper temperature. Then the fluid is pumped in and the excess is allowed to drip out until it reaches the bottom of the fill port.

If the transmission was lowered as he said that means you now have an incorrect fluid level in the transmission. Does he even know that it must be level to check? And the temperature requirements of the fluid?

Please, please print out the correct procedure from the JTIS and make the shop follow it exactly. This is not an option.

Also get it to a shop that understands what must be done. He does not and this is the simple stuff in the beginning!!

Also if he lowered the transmission did he remove the drive shaft?? Because the bolts/nuts/washers are used to balance the drive shaft and again MUST be replaced in exactly the same positions.

Do you have any vibration problems? If not I would do high speed testing to be sure.

I won't comment on the fluid used as you have been given good advice above.
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^ what he said, plus there's a sticky on filling which is fine for checking the level and someone I think posted a link to Rev Sam's video

 

You definitely dont want to check the fluid at an angle!

Flat even surface or on a lift flat and level, you should never have to drop the gear box for anything other than taking it out to rebuild it! As the guys pointed out you will cause alot of "other" issues if you do this.

My guess is that with yours also being a 2003 STR like mine you may be on borrowed time anyway with the guibo connector from the back of the gearbox to the front of the drive shaft. Any messing with that especially on 10 year old mid mileage car can really cause you to have some 60mph and up vibrations, and not the Beach Boys kind of "Good Vibrations"...

-Cheers

 

I do not know how the Lemon law works.

 

Doesn't sound like lemon law but another law... implied warranty or some such?