Dear Jaguar enthusiasts,

A small introduction. I live in the Netherlands and after a few Jaguars (XJ6 ‘70 - 2x XK8 ‘96&’97 - XK ‘09 I now have my long sought ‘96 XJR in British Racing Green. Long sought for as a lot of viewed cars had severe rust problems.
Mine has another problem which I don’t how to solve.
After around 40 km’s when engine and gearbox are hot it starts to shift very rough and fast towards lock up. Even when I do 50 km/hr it shifts up to lock up.
At 100/120 km/hr it sometimes shifts back to 3rd gear.
It has had a proper power flush but as the gearbox does shift very smooth the 1st 40km distance I suspect an electronic malfunction somewhere.
Any suggestion where to look / test and has anyone experienced the same problems and has tips how to solve.
Your tios and thoughts are very welcome and appreciated.

 

There are shifting solenoids in the transmission controlled by the transmission ECU

The XJR has a GM transmission

The solenoids when hot can drop out and can be read from the connector on the transmission or on the ECU connector down low on the passenger side near the front foot rest

There is a servicing level to the GM transmission , but I don't have one

First thing is the proper service level

 

Not sure what you mean by "servicing level"

Cheers
DD

 

Transmission fluid up the dipstick after a certain cycling the transmission when hot through the gears as you sit in the driveway

 

You can Google "4L80E rough shift when hot" and see what comes up.

Check transmission wiring harness where it enters the transmission. Excess transmission movement can damage the wires.

If nothing concrete is found, replacing the A and B shift solenoids and both speed sensors on general principals isn't a hateful idea. As often as not odd symptoms will be cured. A DIY-able job, but messy. Maybe $200 in parts?

Cheers
DD

 

Ahhh.

Jaguar issued a TSB regarding fluid level with the 4L80E transmission directing that the level be topped-off right to the "max" line on the dipstick with fluid HOT. I can't remember the rationale for this as opposed to simply using the "safe range" on the dipstick. But they felt it was important enough tp issue a TSB [shrug].

Cheers
DD

 

Couldn't find that one in the list

JagRepair.com - Jaguar Repair Information Resource

 

Appreciate this information very much.
Monday I will have a ‘read out’ through the OBD2 socket and hopefully it will give me a clue.
If not changing the solenoids/sensors will be next.
I will let you all know. Hopefully with some positive news

 

OBD 2 socket has very few transmissions items to code but worth a try

Only 2 solenoids of one resistance value and you have 2 speed sensors of a different resistance value but hard to see a fault as heat expansion related

To find the connector map on page 23 bottom right corner and 81 at the transmission ECU connector

Remember the connector map is looking at the module

Solenoid A / pin 39 to 53

Solenoid B / pin 43 to 53 also

Input speed sensor / pin 37 to 50

Output speed sensor / pin 51 to 36

The solvent flush ( from other transmissions as well in old solvent ) may have freed up some metalic metal shavings to collect on the speed sensors to cloud over their input to the ECU shifting regulation , just wipe clean , but that wouldn't be heat related but still clean to tidy up

In clouded speed sensors the faster the rotations the more the fault shows up ( bunched up deformed pulse waves harder to discern ) , so higher speed related either engine RPM input or driveshaft output ( vehicle speed )

Probably another main large transmission filter change

jagrepair.com/images/AutoRepairPhotos/jagxj1996.pdf

 

For unknown reason I can’t open the given Jagrepair pdf. Will try again..

 

That PDF address didn't seem right let me try again

 

See attached file below

 

Excellent! This works fine. Thanks.

 

Ensure the transmission ECU connector upside down there is reinstalled fully as someone had his ajar / loose

 

Shift solenoid resistance value probably 30 ohms

Speed sensor resistance value probably a lot higher at 1300 ohms ( inductor like the crankshaft position sensor )