About four weeks ago I got into my XJ-S and noticed first no door light or interior lights that come on automatically. Key in starter, nothing. Completely dead electrical wise. Checked battery nil reading. Bugga, need new battery my first thought. Battery only 2 years old, car started day before why completely dead overnight. Doors were shut, interior lights out what gives?

Decided to put charger on battery, removed both negative and positive cables first, Charged battery for 24 hours. Reconnected to car. Car started immediately all systems go. A week later after at least 3 days idle car started perfectly and has done so ever since. I’m still wracking my brains what caused this power drain. Obvious signs like interior lights discounted. I’m sure I would have noticed interior lights on if doors not firmly shut.

just out of interest has any of you 3.6l owners if experienced any thing similar. What have I missed.

Mike

 

Trunk left open or ajar?

 

No, I checked that, I have an on off cut out switch in addition to the lid pressure switch.

thanks anyway.

 

Had same problem with mine years ago. Came out one day and headlights were on.
There is a computerized switch box for high beam. Why?
Disconnected it and wired up low beam only and also fitted a disconnect on battery terminal. Battery would still be flat occasionally so now always disconnect battery. It is also a good theft deterent.
nofking

 

Hi Mikekeay

It could be you Car Alarm or Immobiliser, as even with the Ignition Switched off, these devices are listening out for a Signal, which can cause a Parasitic drain, where this caused such a problem on my Car that I took the immobiliser out

I also use a Battery Discarnect ebay about a Fiver and this solved every single one of those problems and was one of the best things that I have ever bought