Thank you Jeagar, but I'm really not. I consider myself to be the least knowledgeable and helpful member around here. There's more help that I take and receive from these forums than what I am able to provide.

 

Can't remove gear knob which prevents me removing all but you can see the switches here. Guess the second one could be the culprit. WD40 applied and can here it "click". No change however. Started up fine, selcted 2nd put in S mode had 30 min ride then suddenly lost the manual option 2-5. And lost the S mode. Change switch next perhaps.

Re car colour - not sure - advertised as Pacific Blue Pearl but that could be incorrect.

 

I think I have been looking in wrong place. From another thread a couple of people have exactly the same issue(s) and it's often this unit - which looks quite easy to replace! (Part 27).

https://www.jaguarclassicparts.com/uk/part/C2N2467

 

Tried cleaning it - bit of improvement. Now got a new switch on order. Linear Switch Module.

 

Pulled out the old LSM and replaced with new.

A little bit fiddly but like every job you do the first time the next time you do it <if ever!> you will be right on it.

All works ok but I did have to wiggle the switch before screwing down to final position to get 2nd gear to work.

I will only know after a few weeks whether it's cured it.

 

Reviving an old thread since whatever glitch is talked about in this forum eventually happens to all of us.
So the other day (Saturday) I was driving the car and at some point noticed that the Sport Mode light was not on (I always keep in Sport Mode). I just figured it was a bad connection and depressed the switch a bunch of times but still never lit. Then I noticed I could not manually shift into ANY of the drive gears--it just stayed in total automatic mode. There was NO problem driving and the car shifted fine but totally automatically. When I came home before pulling into the garage I made sure that I could at least get into Reverse and there was no problem doing so. When I finally pulled into the garage and put in Park, I noticed the P blinked a few times and don't know what that signifies. I check a few fuses and there were no problems. The only thing I had done out of the ordinary before driving on Saturday was to hook up the CTEK charger to top off the battery (do this every few months).

So today (Monday) I start up the car and the Sport Mode light is on like normal and I am able to manually shift without a problem. Is this the same type of hiccup that happens every so often like when the DSC warning comes up occasionally? Or did my topping up the battery cause the glitch?

Mark99 sent a PM to see if you solved the problem by changing the linear switch or ?

Thanks,

Doug

 

The J shifter is an electronic module and communicates with the transmission over CANbus. Your shift module probably had a communication error of some sort and either wasn’t sending or the transmission decided to ignore the messages.

Did the PRND letters light red as normal or were they off? If they were also off perhaps it was a power supply issue to the J module.

 

The J-gate module is receive only, the ecm/transmission and switches make the decisions. You may want to check the codes to see if there are any. The edge connections on the J-gate module are twitchy in any case, they can affect the whole CAN bus continuity, but I'd see if there was another source before I took it out and resoldered.

May be difficult to diagnose if it decides not to happen again and there are no codes.

 

ccfulton/crbass--I didn't really have the presence of mind to see what was lit or not lit on the shift plate, except for the blinking P when I finally put it in park. It has been a few days and, knock on burl, no problems. But now I take time to notice what lights up when I put the key in. What I have been seeing the past view days is that when I turn the key on but do not start, the Sport Mode lights up as normal along with the system check lights on the instrument panel.

I have a feeling that it was not a coincidence that the one time I had a problem came almost immediately after I used the CTEK to top off the charge on the battery. Maybe there were some excess electrons floating around somewhere that falsely triggered the incident.

I did a bit more browsing through the forum to find other similar posts and the "solutions" ranged all the way from turn off the car and start again (worked for me), clean contacts at the transmission, clean contacts at the linear switch, replace connector to the linear switch, replace the linear switch. The most curious was some guy (forget who) who claimed that he somehow tracked the problem to accelerating from 3rd to 4th and the solution consisted of a $3,800 transmission rebuild?!?!?. That last case sounds kind of off-the-wall.

Doug

 

Seems like a win if it doesn't come back. Since the symptoms were that just it motored along fine auto shifting, seems like even if it comes back, you can dig deeper then. If it doesn't, one more effort saved for the next entertaining gremlin.

 

I am trying to avoid "gremlins" these days since my wife is starting to harp on me that I should buy a "new car" for no other reason that the Jaguar is getting on 15 years old. There have been very few problems with the car over the past few years (octopus hose replacement, broken oil cooler line, leak at transmission gasket) each of which cost no more than $600 and the car only has 57,000 miles. I suggested getting a new car and keeping the Jaguar as a 3rd car.

Doug

 

Far be it from me to suggest keeping things from your wife.

On the other hand, a $500-$600/month car payment could put a rebuilt engine or transmission into the Jag every year even if you didn't want to do it yourself with a bit left over for an annual octopus hose replacement...

 

The blinking actually tells you something about what happened.

The TCM believes it saw something from the J shifter that shouldn’t happen, like skipping a gear in the J pattern or rapidly toggling between two gears. It is a command interface so the transmission won’t actually DO anything but it will register an error and start ignoring the inputs from the J shifter, including sport mode.

I caused this a few times when I was playing with my paddle shifter project but it is all temporary. Shut the car off and back on, the modules reestablish communication and all is well.