2002 Jaguar X Type Auto trans with 113K miles. The trans has been acting up lately. It started with an occasional engine would rev up before hard shift. So today the Jag ran normal for about 2 miles, then a hard shift after which I drive another mile and the trans won't engage any gear except 2nd and Gearbox Fault warning on display. I have checked the shifter selector on the trans and there was no play. I pulled out the TCM and there were no signs of water damage. I then replaced all 9 Transmission Solenoids and filled the trans per the procedure on this site. I am still getting the following codes;
P0733-Gear 3 incorrect ratio
P0734-Gear 4 incorrect ratio
P0778-Presure control solenoid B electrical- I just replaced this solenoid so I do not think this is the problem.
I have searched this forum and there are many posts for the above codes but no one has posted the root cause/repair. I believe it is either the transmission speed sensors or the TCM.
Any insight/suggestion on the cause/repair of this problem will be appreciated.
Also has anyone replaced the transmission speed sensors and if so could they post the procedure.
Thanks
Howard

 

Howard, looking at the codes, both the P0733 and P0734 have the same 3 possible faults: 1) J Gate incorrect setting, 2) Transmission oil level low, and/or 3) Transmission mechanical failure. It also goes on to say that these codes may appear if "Note: If a shift solenoid failure
DTC is also flagged, correct shift solenoid DTC first." This is where P0778 comes in. This involves your 2/4 Brake solenoid. The faults for this are: 1) Transmission to TCM 2/4 Brake pressure solenoid circuit: open circuit, short circuit. 2) Transmission internal 2/4 Brake pressure solenoid circuit: open circuit, short circuit, 3) TCM Ground circuit: open circuit, high resistance, and/or 4) 2/4 Brake pressure solenoid failure. So, it could possibly be your pressure solenoid again. The question that I have is whether you replaced just the solenoids or if you replaced all the wiring back to the connector where the car plugs into the tranny. I ask this as other members have had issues with the insulation breaking down on the wiring, leading to grounds and short circuits which caused their tranny to run like hell.

If you want the resistances of the solenoids, I can get that for you. But ,I think your better check atleast at the moment because of having new solenoids is doing ground checks where you measure each circuit to the body of the tranny. All of these should read greater than 2 megaohms. If you have one reading low, that is probably your issue and unfortunately, that would involve opening up the tranny again to fix the wiring.

 

Thermo,
Thank you for this information. The number 1 issue that you mention is Transmission to TCM 2/4 Brake pressure solenoid circuit. Is it possible that I have a problem with the TCM because I checked the wiring on every solenoid as I replaced them so I did not replace the wiring. Is there a way to check if the TCM has failed?
Howard

 

Try post #3 = a HARD reboot.

https://www.jaguarforums.com/forum/x...module-170074/

 

hak, i have in numerous posts put up the resistance of the solenoids and what pins you have to touch. I would say if you can get past the resistance checks of the solenoids, then that really only leaves the TCM as your source of problems..