Bought an XJ about a month ago and have a few probs.

She started and ran fine when I bought her and the week following. About a week and a half after purchase I went to start her and battery was dead. No keys were in her and no doors left open. Nor was there any overhead lights left on.

I charged her and she started again and continued to do so for a few days. I went to pick up the kid from school and when I went to start her and leave from school she just turned and turned without starting. i got her home and she sat for a couple days before I put jumper cables back on her. She started again for a couple days then about 3 days later she lost her charge again and didn't have enough power to turn her over.

I went through the diagnostics and the only thing that said was that she had a prob with the speed sensor (speedo works sometimes) and that the battery had been disconnected in the last 50 on off cycles.

Any ideas what might be wrong with her?

Thanks in advance.

You should include the year and model - so we know what to talk about - the models
for the XJ go back to 84 and have at least six changes.

Not an uncommon problem with older XJs - first check the battery to be sure it
is charging OK - disconnect it and charge it - with the cables off - and then
check the voltage - say after charging over night - You are looking for good
voltage 13V and above - below 12 after a full charge means the battery has
a cell going - check the leads to make sure they are not corroded - clean them
with a wire brush and use die-electric grease on them to make sure they contact
the batter OK - check the water level - to see if some of the cells are dry - if
the are try to find out why - holes - leaks - etc. IF FILL THEM USE DISTILLED WATER
ONLY.

If the battery looks OK - and the cables are clean - start it up and check the
voltage during a charging cycle - again you are looking for 13.6 or higher - meaning
the alternator is changing it OK - the alternator and/or the belt might not be tight
and thus not charging correctly.

If you have a good solid battery, a tight belt , and a charging alternator then you
have a voltage drain - a short or a device that is on - which is bleeding your
power away - common problems are dome lights - radios - other accessories - to run
this down you need a good digital volt meter that can measure current - so you can
go to the fuse box and check each circuit to see which ones are draining the battery.

Thanks for the informative info.

Sorry about the make omitance.

The vehicle is a 1991 Cherokee Laredo.
4 Door
4.0 Inline 6Cyl
Auto Trans

Oh - my 90 XJ has this really cheesey headlight switch - if you don't turn the lights
off before you release the key - the headlights stay on - sometimes way too long before
they turn off.