I have a 2005 XK8 that had the black button that slides down on a post undern the accelerator pedal in the glove box. When I found out where it went I replaced it to that position.
My question is, do I need to reset the throttle position sensor, It does restrict pedal travel.
If so, how do I do that?

Jack

 

On some cars that button is just to provide physical feedback to the driver (it's not connected to anything as the software figures out where the pedal max is).

I doubt you need do anything.

 

I can't see any mention of kickdown switches on either of the ZF gearboxes used but the MB box in my XKR does have one in that position and needs to be set to a certain throttle opening. I guess on your car it may be a simple pedal stop

 

Thanks. It is just a pedal stop, no wires. Don't know why it needs it.

Jack

 

It doesn't need it. It's to make some drivers happy. They can feel when the pedal is right down.

No idea who thought it was worth building into any car...

 

Mine is an 03 car so I just took mine off and adjusted my pedal so it used the full travel of the pedal. It was annoying me.

 

What is the procedure for adjustint the pedal.

Jack

 

You need an OBDII reader so you can see the throttle position but once you have that hook it up remove the black button under the throttle pedal. Open the bonnet and under the left hand side looking at the car front on so on the drivers side if you are in the UK or the right hand side if you are in the US there is a black cover over the corner of that side lift that up and under there there is a black box with a cable running to it, open the black box up and there is a ring and a cable with grooves on it with a painted section on it, Detach the hoop so it can move freely and then adjust it to where the OBDII reader says the position sensor reads 100% when the throttle pedal is at the new full travel. I'm not the best at explianing it but that's the jist of it.

 

Thanks Kuddlesworth

Jack​​​​​​​

 

If it's drive-by-wire just leave it be, it's not broken - but you can break it!!

The software learns the max TPS value and regards it as 100% without further drama.

 

Thanks JagV8

Jack

 

It appears in the 2001 to limit cable stretch if adjusted properly.

 

Thanks
Good to know what it is actually for.

Jack

 

"It" was there long before 2001. It's primary function may have changed but all 4.0 litre XKR's are fitted with kickdown switch in that position and the circuit wasn't deleted for XK8's until vin 024687.
As stated in an earlier post some form of positive stop is a good idea for fly by wire pedals, they can and do break with heavy foot applied.

 

Interestingly, if one pushes the pedal with the fingers, it is possible to feel two separate functions. Simply from the way that it feels, it seems at least on my car that the kick-down/start-up fuel cutoff is within this second much shorter step of the pedal travel. Makes me wonder if the reliability of the button switch was questioned due to things such as carpet and floor mats, and it being simpler to make it a part of the drive by wire hybrid cable system.