Battery goes dead overnight . I believe the trunk light is staying on. Whatever might that fuse panel be and where is the switch that shuts the light off. Can find either.

 

Bob,

Unclip the light and take the 2 wires off, then see what happens. I did that years ago and have never connected them since.

Paul

 

Set your phone to record video, put it in the trunk and close it. Then open, and watch the video. That'll tell you for sure.

Jon

 

On LHD cars, the fuse for the trunk lights is located in the fuse panel under the steering wheel. I've removed my trunk light fuse because I leave the trunk open when I use a trickle charger.

 

Thanks, when you pull that fuse does it also disconnect other lights?

 

No, the fuse is just for the interior trunk lights. But I will go check to make sure all the other exterior lights are working now that you planted that seed of doubt.

 

The exterior lights still work.

 

Had the car into the shop. Could find no real drain, but car won't start in Park. Shifter cable stretched and switch can't tell it's in park. Their diagnosis is that this could be the problem because car doesn't know it's in Park and some things may not shut off when the car is turned off and the key removed. This is a 95 XJS 4.0 2+2, could this be possible without many computer parts being on this car?
Secondarily he can't find a new cable and is afraid to try and adjust the switch as the cable may break. Cable part number is MHF4930AA, any suggestions as to where to get a cable/
Thanks for the previous replies.

 

It might be that the switch has become unadjusted, rather than the gear selector cable has stretched. I highly doubt the cable would break.

 

I dont think the car is clever enough to keep different systems active if its not in Park. I've often left mine in Neutral.

As regards the battery drain, connect a multi-meter in line on the battery terminal and just measure the current draw with the ignition off and boot light disabled. f the battery is going flat, there's either a current draw or a duff battery

Good luck

Paul

 

Thanks, I Agree that this 95 Vintage has no brain to leave things on. The cable is very rusty, reason for not trying to adjust. Could parking brake light or light out warning light staying on have anything to do with it?
The shop could find no drain with meters, left it for three days.
When AAA came to start the car the tech said it only had 100 amps left in it but battery tested good.
Puzzling?

 

The only somewhat common power drain on these cars tends to be the power antenna. I would disconnect it and see if that solves your problem.

How old is your battery. I had an Interstate battery that gave me all kinds of fits. Once I finally replaced it, I think two years in, all the little gremlins went away. I think it was just a bad battery. These cars are indeed very sensitive to proper voltage. One way I know my battery is nearing the end is when the power locks begin to work less consistently.

 

Bob,

If the technicians have monitored it over a period of time and found the current draw to be acceptable, then I would:

- Disconnect the battery
- Measure the voltage
- Fully charge the battery (disconnected)
- Leave 24 hrs, measure voltage. If under 12v, condemn battery
- if above 12.5v, reconnect
- Start car whilst monitoring voltage, Perhaps activate inertia switch to prevent starting and allow cranking to run longer
- If voltage drops to below 10v during cranking, I'd question the integrity of the battery

It's not a proper drop test, but it's a good start.

Good luck

Paul