Today on the way to work my car went into failsafe mode. I drove home at about 10 miles an hour with a line of cars behind me - believe me it sucked. I just started it up and it displayed a bunch of codes on my OBDII reader (P1222, 1111, 1642, 1638, 1000, 1637, 1643) most of the codes deal with the CAN bus/ECM and the one of interest was 1642 which dealt with pedal position circuit - low input. It then refused to go into gear and I had to take the plug out by the shifter and override it. I started it after reading the codes and the dash displayed "Restricted Performance" I just started it again and the only issue was a check engine light. Any ideas? It is a 2002 XKR

 

I would first check the battery and connections, both positive and ground. If the battery is much below 12.3 V it will still start the engine, but create chaos among the modules.

 

Probably bad power - usually the battery on its way out.

 

+1

A failing battery is the number one regular cause of weird electronic faults on these models.

Look on the bright side - at least it fixed your concerns about the brake performance.

https://www.jaguarforums.com/forum/x...002xkr-184195/

Graham

 

Thanks for the info, I hooked up my battery charger and it read 12.3 volts to start (I charged it overnight at 2 Amps) which is low. I need to figure out the age of the battery - a bit misleading in appearance as it stays clean in the trunk. Is there a simple test for the alternator - I remember that if you detach the positive side of the battery and the car keeps running then the alternator is OK. Is that still a viable test?

 

Found this on-line

 

If you have an OE battery (Varta brand) the date of manufacture is stamped on the negative terminal post.



It's in the format WW/YY for Week and Year. This example is Week 23 of 2012.

Graham

 

Appreciate all the posts in response to my query, as it turned out the battery was at 12.3V even after a night of charging (did not budge). I started the car with the old battery and it was reading 14.3 which tells me the alternator is working properly. I just installed a gel battery and it is under charge. I had the battery terminals disconnected and the check engine light is gone, tomorrow I will use my OBDII reader to remove the codes. Hopefully this solves the problem. Maybe I can do something fun like upgrade the brakes!