Hi, a

strange thing happened- I removed my battery to have it recharged and after installing it I realized that the arrow on the speedometer was all the way to the right - see photo -
How can I fix this issue ? Someone told me to reboot the computer that’s in the car by connecting the negative and positive together ,

I’m is that true ?
ps the miles are still registering -
Thank you, Terry

 

Terry,

Lovely car! And only 12,000 mils?! Wow!

The XJS isn't really that clever a car. It doesn't have a "computer" controlling the speedo. It has a sensor in the rear diff, which send a signal to an interface unit which then feeds the trip computer and the electronic speedo. If the speedo miles are incrementing correctly, then the sensor, interface unit and speedo are working.

I can't think how the speedo needle bounced itself all the way over unless perhaps there was a strange current spike if the ignition was on when the battery was reconnected?

Unless somehow the needle resets itself if you disconnect and reconnect the battery (I wouldn't be too hopeful) then I think I would disconnect the instrument cluster and try to move the needle back by tipping the instrument cluster around.

Good luck Terry,

Paul

 

You will have to remove the instrument panel and push the needle back over by hand.

I'm not sure what caused that, but I think the only other option you would have is to roll the car....but I think you'd prefer to remove that instrument panel...

 

Hi Terry

Not a common problem but not unusual either and there is 'Only One Way To Fix It' and just as a matter of interest or not as the case may be, we both have the same Car!

Both Celebration Convertibles and my Car once had exactly the very same problem as yours, with the Speedo Needle flicking right over when I put on a new battery

Forget all about connecting wires and resetting the trip computer, as none of that stuff works and I even tried a Magnet and that didn't even work either!

Thankfully its an easy fix that is really a 'Walk in the Park' and this involves removing the 'Speedo Binnacle' and then once having done so, hold it in your hands as if it were a Steering Wheel and then revolve it in the same way until the 'Speedo Needle' falls back into place and then put the 'Speedo Binnacle' back, reconnect the Battery and you are go to go!

Here is a Step by Step description of How to do this job including all the Photos you will ever need to see and should only take you about 30 Minutes

Speedo Needle Flicks over and how to get it back on an XJS 4.0L

In this Link there is also a description including a Video of how to Test the Valve Block of the ABS on an XJS V12

 

Thank you every one I really appreciate your replies