89 Jaguar xj6 battery drain

I own an 89 jag xj6, (Im beginning to think that might be bad news :slight_smile: ). Something seems to be draining the battery. It can start fine in the evening but by the next morning its dead. If it sets too long its completely dead… nothing… The alternator appears to be charging, after running it awhile it will start again. I put a new battery in it several months ago. The former owner said something about it maybe being a switch of some sort that has something to do with the climate control system? Any input and ideas would be greatly appreciated, this is really draining…:frowning:
thanks! woodwayne

IIRC, Jags of that vintage still relied on Lucas electrical components, and if your car does have Lucas electrical parts, that would be really bad news.
Mr. Lucas, nicknamed, “The Prince of Darkness”, came by that moniker for very good reasons.

Whether your car has Lucas parts or not, I would suggest that you seek out a shop that specializes in Jags, as they would be the most likely to be familiar with the very quirky electrical systems on these cars.

The first thing you do is measure the parasitic draw. You don’t need to be a jag expert to check if you do or don’t have a problem.

disconnect the positive terminal from the battery (first make sure everything is off on the vehicle). then place a test light clipped on the terminal and the sharp end put it on the possitive post if there is a light (except mega dim ) then that indicates a draw on the system. now you need to isolate the draw by removing main fuses if one makes the light go out then start removing secondary fuses on that circuit until you isolate the actual draw. it has been my expirience that you need to start whrere anything new has been added (Radio, amps, alarms, navigation, etc.) good luck let us know how you fare.