Well, I have had 70,000 trouble free miles with my 2000 XK8. I made arrangements to change the ZF 5HP24 fluid and the day I went to drive over, the car wouldn't shift out of park! The J-gate felt tight and it finally slid into reverse after too much effort. More effort and it went into drive.

Fundamentally, the transmission works fine (no codes) but the J-gate just doesn't want to move and feels tight as if the cable is fouled. Today I noticed that the engine will turn over, but not start, when in Park. Put it in Neutral and it fires right up. Also, it is reluctant to shift up to third unless I wiggle the J-gate.

It is as if a switch is not being properly engaged. Is this the Rotary Switch?

My plan of attack is to look at the shift cable adjustment and the cable itself to see if it is fouled.

Any other recommendations would be appreciated...

 

My ZF-HP5 transmission suffered a split A-drum failure a few years back, leaving me with only 4th and reverse gear. (Dash error code displayed: Gearbox failure)

I think the J-gate and cabling have quite a bit of mechanical tolerance and not prone to error.

Did a complete overhaul of the ZF-HP5 and she's working just fine. The A-drum will fail eventually, just depends on when...

 

When the EARTH cable fails, the current needs another path and the gearbox selector cable becomes an alternate ground?
The cable is NOT designed as a current carrying part and can melt.

I remember 'back-in-the-day' people complaining about how the speedometer stopped working and the engine cranked slowly all of a sudden.

The speedo cable melted from the failed ground cable. (the starter needed a ground somewhere)

Just a thought

 

I ended up making a minor adjustment to the cable and all is well.

Removing the console was a 15 minute job and the top side cable adjustment was easy. It is very sensitive to position, but easy to adjust. I cleaned and lubricated the various sliding parts and it made a noticeable difference in the "feel". As a bonus, my gearshift position lights became operable after many years of darkness. I presume I wiggled the connector.

I noticed that the rearmost microswitch is about to fail. The arm was off and the rubber covering in the button worn through. The switch looks common enough, but the riveted installation might prove tedious.

In the end, though, I'm not satisfied that I've resolved the stiff gearshift movement. It was, in my estimation, too stiff to be a simple lubrication problem. Still, I took it out for 50 miles and the transmission performed flawlessly and so did the gear selector itself.

My car is going on 21 years old now with 140,000 miles on it. I get compliments every time I take it out and it is a pleasure to drive.

 

I want to wrap this issue up as I think it is a common enough failure and has some interesting turns to it.

The trouble was with the rubber boot on the transmission end of the shift cable. It was split and deteriorated to the point that the unprotected steel end of the inner cable sleeve had rusted. This interfered with its movement through the outer sleeve very effectively (and unpredictably) binding the cable. It is an easy DIY replacement IF you can get to the bottom end.

Up on top, the 4 micro switches require pretty precise and consistent cable movement. Even the smallest imperfections in movement will create trouble and confuse the CANBUS line.

Also, now that the cable is properly adjusted all the indicator lights on the shift gate work! For years I had thought them to be shorted out but they had, in fact, fallen victim to the cable boot!

Hope this helps!

 

For that, double check the status of the brake switch. Is the adjustment is off, the car "thinks" you have your foot on the brake and will not upshift. Start by checking if your brake lights are on with your foot off the brakes. There is a slider/ratchet mechanism on the trigger of the switch that can be adjusted to fix this problem. Yes, it is $0. To be clear, this is not an indication your brake switch is "bad", just that it needs an adjustment to engage at the proper travel of the pedal.

Best of luck, keep us posted.