Do you have the 5 speed transmission? I thought that when Jaguar went to the 4.2L engine they called it an '03 and had a 6 speed. MY designation between US and GB can get a little strange.

How many miles? Any leaks? Check/change fluid. Does the problem appear under hard acceleration or normal? THUNKS are a sign of a failing transmission but I had one that was a Transmission Control Module issue.

 

hi there

i seem to be having a similar problem myself. i've got a 1999 XK8 coupe. when i put it into 'd' (drive) or 'r' (reverse), i seem to get a hard 'thud' as it engages gear. this seems to be more prominent when engaging reverse. also, sometimes when engaging reverse, it seems to hesitate a little then 'bang' into gear. all other gears seem fine when driving.
i've just had the tranny serviced (oil and filter changed) in the hope that it might cure it, but its still the same. i've been told i may need a transmission rebuild, but i want to try any other options before i go forking out 2 big ones (thats 2000GBP.....ouch!) .
not sure whether the guy was feeding me a ridiculous theory, but he also says that it could be a problem with the throttlebody that could be sending the wrong 'messages' to the tranny.

any suggestions?

terry

 

Disconnect the battery, wait 5 minutes, insert key and turn to starting position -this drains any residual power from the ecu. Wait 5 more minutes, re-connect battery. start car and drive to nearest stretch of open road. From a standing start, stand on the gas pedal and let the car shift through each gear to about 80mph.

This should reset the transmission shift points to match the throttle position while driving.

If you still have the problem, off to the dealer you go.

 

Found this TSB on another thread here, don't know if this applies:

TSB : Harsh Transmission Shifts No.S307-17
Vin : M45255-2.5L M96288, 3.0L M96322, 4.2 N/A M96316
This Technical Bulletin has been issued to address customer concern of harsh transmission shifts, particularly 3 - 2, 2 -1 roll out and 1-2 up-shifts.
: The adaptive shift strategy drifting over-time causing higher than normal clutch pressures.
: The customer must be advised to use normal mode not sports mode) for 200 miles (321km) and to try to void full throttle/kick down over this period.
: To eliminate the issues outlined in the summary the transmission adaptions must be cleared and the Transmission Control Module (TCM) and the Engine Control Module (ECM) should be re-configured using the Worldwide Diagnostic System (WDS) with software release JTP 759/35 or later. Should a customer express concern, follow the Service Instruction outlined below.
1 . Position WDS alongside vehicle, switch Portable Test Unit (PTU) 'ON' and allow software to load.
2 . Ensure the ignition is switched 'OFF', hand brake is 'ON' and the transmission selector lever is in park.
3 . Connect PTU to vehicle using diagnostic cable. : Ensure WDS is loaded with software release JTP 759/35 or later.

4 . Enter VIN and check the TCM and ECM for fault codes, any associated repairs are to be carried out as a separate Warranty Claim.
5 . Navigate to configuration main menu.
: It is imperative operations 6, 7 and 8 must be performed in that exact order.
6 . From the vehicle configuration main menu, navigate to and run 'TCM adaptations clear' application.
7 . Select and run 're-configure existing ECM' application.
8 . Select and run 're-configure existing TCM' application using the 'Coded Access' route.
9 . After the re-configuration of the ECM and TCM is complete, switch 'OFF' PTU, disconnect from vehicle and return WDS to original location.
Carry out the adaption drive cycle road test:
10 . Drive the vehicle for ten miles in an urban environment to provoke the transmission to carry out upshifts and downshifts. Use light throttle only and do not exceed 2500 rpm. At one point in the drive cycle, when the traffic conditions allow, accelerate gently to 60mph (95 km/h) then allow the vehicle to coast down to 25 mph (40 km/h). : This process must be carried out in normal mode (not sports mode). The transmission fluid temperature must be above 60 deg C (140 deg f) (vehicle at normal operating temperature will ensure transmission fluid temperature is above 60 deg C (140 deg f)).