Hi,

I've got an odd problem - my 98 XK8, if it's been sat for a couple of days, it stops closing the windows when the doors are shut.

I know how to reset this and have done every time. I test it afterwards and it works fine, but a few days later it forgets again.

The battery is only about a year old and is charged enough to start the car, etc, so I doubt it's that? Any thoughts?

 

It probably is the battery, or a poor connection at the battery terminals.

 

Having enough voltage to start the car, and having enough voltage available at all times to maintain the vehicle's processor modules while the car is off, are two very different things. With this type of vehicle, the modules continue to function even when the car is off, but under normal conditions, the vehicle will enter 'sleep mode' to conserve battery power. A parasitic drain on the system would account for your symptoms, and is characterized first by the windows losing their memory. Next weird electrical scenario's play out; once while starting my car the vehicle began the 'top down' procedure, and began lowering the rear windows and releasing the top latch, although I was no where near the top up/down button. Search the forum for 'parasitic drain', but I would be willing to bet it is the little 'flap/door' in the ignition cylinder that is supposed to close when the key is removed. It gets gunked up with grease and dirt, and the door/flap stops closing completely and consistently, and the loud 'SNAP' is no longer heard when removing the key. Therefore the car never goes to sleep, and this will drain the battery in ~36 hours. There are procedures for cleaning the ignition, and for tracking down other possible parasitic drains on the system such as, the light in the glove box not shutting off, trunk light micro-switch goes bad or gets dirty and trunk lights remain on, bad ground etc. I plan to post the pictures of my ignition cylinder cleaning procedure, but it is pretty straight forward; and I have not had any problems with a parasitic battery drain since I cleaned mine.

 

My '99 suffers from a similar problem primarily because it doesn't get 'exercised' as often as most cars do. My wife's XJ8 gets everyday use while my car may sit for anywhere from 3 days to a week at a time. My battery is probably at least 3-4 years old and these cars are notorious for getting funky if the battery voltage drops below about 12.2 or 12.3 v. I can easily reset the windows and they'll generally last for a week or two but it will eventually reoccur if the car sits for s few days.

Put a multimeter on your battery and see what the static voltage is and as previously advised start looking for parasitic voltage drain. You might also do well to check the many electrical grounds on the car as it is, after all a 17-18 year old car and merde happens<G>.

Failing any obvious findings you could get a relatively inexpensive battery maintainer (I have several for my motorcycles) that would not only keep your battery topped off but would also extend your battery's useful lifespan