My Xk8 is a daily driver with 110,000 miles on it. It runs great and I have absolutely few (not many) complaints. Today I was backing out of my driveway and when I press down on the throttle with the transmission in reverse, it hesitates and moves backward (like it is pulsing...best word for it) a few feet but as soon as I release the throttle it comes to a stop. Almost like the parking brake is on although it is not.

Since I live 4 hours away from a Dealer, does anyone have any suggestions? I have a local shop that has done several jobs for me and as long as it is easy, they will give me a hand.

Does, anyone have any ideas?

Thank you all in advance.

Update - I tried a soft "reset" I do that so often and it cures so many problems I keep a number 10 socket attached to the battery full time = That did nothing
I did notice one thing when I was trying it out. A noise I have never heard before. When I press down on the brake, there is a slight clicking sound just underneath the gearshift knob. Don't know if there is a relationship but it is a brand new noise to go along with my reverse problem

 

The clicking is the brake interlock with the transmission shift mechanism. The poor transmission performance may well be a need for a fluid change if never done. While mostly seen on forward gears who knows. Also you do NOT have the emergency brake on? You know it's not just pull lever up and down and didn't get set by accident?

 

Binding brake?

Low trans fluid?

 

Thank you for your response. I worked the handbrake several times to make sure it was not engaged. The "braking" feeling occurs only in reverse. The transmission feels OK in reverse but it is as if once engaged in reverse the rear wheels have break pressure applied.
I think you are right about the brake interlock clicking under the gear shift mechanism.
Also my brakes are soft and brake travel is longer.
My brake fluid reservoir is full so I don't think anything is leaking. Is there a way to test the master cylinder?
I appreciate your input. I also have a reply of "binding brakes" Can they bind only in reverse?

 

As to the handbrake - I can set it and the car will not move forward or reverse when engaged. Disengaged and in drive, it will move forward with no problem but not when the transmission is in reverse.

 

ANOTHER UPDATE: After letting the car sit all night, she backed up with no problem. I drove a few miles and let her warm up to temp and she is working fine again. The only remaining sound is the brake interlocking "click" when the brake pedal is depressed in Park which is a new sound. The click doesn't happen in neutral, drive or reverse. Just in Park.

 

More testing update: It seems like it is electrical. Whatever the switch in the console that selects the gear from the shift knob. When the car (as it is now after running for a while) will not back up (breaks locking) the transmission will not select neutral. It moves forward in neutral. So whatever switch,solenoid or relay that controls this function may be faulty. Does anyone know what that may be? That I think I can replace.

 

The sound is a solenoid that is releasing the shifting lever. There is a switch on the brake pedal that activates the solenoid. This makes you step on the brake to get the transmission out of park. It is a normal sound that you may not have noticed before. On my XK8 I hear it all the time if I listen for it.

 

You posted the same time I was typing. I would jack up the car have somebody engage and release the emergency brake. It might not be releasing even though you released it in the cabin. It possible that the spring broke or something is binding the mechanism.

 

Thank you for your answer. This problem is now intermittent in that right now it will move in reverse no problem but if I drive around and stop at a light with my foot on the brake I hear a clunking sound and If I pull over, it will feel as those the parking brake is engage (although it isn't). When this happens I can drive in "D" and the transmission is ok. During this time, the shifter will not disengage in the neutral position. It wants to move forward. If I put it back in park and shut it down for a while and start it up, everything is back to normal. I tried a hard reset just now and that made zero difference.

 

Sounds to me like its the transmission starting to fail. Are you getting any codes. Where is the clunking sound coming from.

 

I ran it for a half hour, Stopping and working the transmission when it worked and when it failed. OBDii showed zero faults

 

the clunking sound comes from the center console - under the shifter

 

This might be above my pay grade. It sounds like transmission. I'll send you PM.

 

It is sounding like something is wrong with the linear switch. It is a circuit board around the shifter lever that informs the computer of what gear you have selected. It has micro switches for all positions. Some folks seem to fix them (starting with contact cleaner), others replace them. Alignment is apparently tricky, so you might want to read up on this ahead of time. Just my thoughts, I have no direct experience with this.

Best of luck, keep us posted.

 

Thank you for your input fmertz!
That sounds like a job I can tackle. It sounds a whole lot better than changing out the transmission!

I will let you know.

 

Hope you get this repaired quickly and cheaply. HOWEVER what I'd really like to see is a little larger photo of the lovely lady in your signature pic?

 

I know I probably seem crazy but I have looked at dozens of drawings of a linear switch and I can't for the life of me see it. Since I am not the kind who just starts disassembling things ***** nilly, Could it be hiding behind this stamped bracket? If so the drawings seem to show the switch sitting on the bracket.



Where is the linear switch in this picture?

 

The photo shows the micro switches he mentioned. They are under the J gate. The photo is from one of my parts car and if you look close one of the switches is missing the metal lever that sits on the switch. While you have the console open start the car up and put it in gear to see where you clicking sound is coming from. I'll bet it is from the solenoid on the top left side of the shift mechanism.

 

Yes, the solenoid is the item making the clicking sound. You can feel it when you put your hand on it. So, there is no U-Shaped Linear switch just the small microswitches?