I need some help please.My 2003 2.5L S-Type will not start after reconnecting battery. I have been trying a few times over the past week or 2. The car has not been driven for a few weeks. I thought front seats might have been causing battery to drain because I fitted different seats, so today I removed the 4 fuses in the boot (trunk) fuse box for seat motors. This did not seem to have any effect.

Before not starting just now the battery before reconnecting was reading over 15 V. The starter motor does not spin and I get lots of warnings and instrument needles go right up. The same as last weekend as in this video.

After not starting just now I disconnected battery and the voltage is still about 13 V. Despite the warning there is some fuel in the tank as well.

 

Welcome to the forum.

Make sure the battery is fully charged. The voltage readings seem okay, but cannot be trusted 100% for determining state of charge.

The next possibility is the security system has entered a theft protection mode for reasons unknown. Look at the security system indicator at the base of the windshield. Lock the car with the key fob. Press the lock button a second time to set the alarm system. The horn should chirp once. Watch the little red light. It should flash once every few seconds to show the system is armed. Now press the key fob unlock button twice to unlock all the doors. The red light should go out. Hop in the driver's seat and turn the key to RUN (Not start yet). The red light should come on solid ONCE for about 3 seconds and then go out. If it flashes anything after that, you've got a stored fault and the security system may be trying to protect the car.

 

Battery reading over 15V sounds wrong - a fully charged battery should be 12.7V ish. Are you sure you're reading it correctly? That being said, that voltage should not damage the car.

You need to get a code reader and read the codes out of the vehicle - there's something going on that's causing the various faults to come up on the dash. It's strange that it's reading low fuel but that in itself shouldn't cause the car not to crank.

What different seats did you fit? Could it be that this has interfered with one of the networks in the vehicle? I can't remember if the CAN network goes into the seat on S-Type but worth checking the circuits?

 

Ooh, good catch. I didn’t notice that on my first read.

That is an unloaded voltage, with the battery at rest. What is the battery voltage when you turn the key to the start position? You may need a helper to assist. I suspect the voltage may drop way off under the massive load of the starter.

What response do you get from the starter? (Sorry, can’t view the video). Do you get a clunk or a groan? Nothing at all?

Are the new seats OEM, from a similar Jaguar? Did the connectors plug right in? Or are they aftermarket or from a different model car, requiring some wiring modifications? Either way, I’d think you could unplug them temporarily for troubleshooting.

 

I did not notice the video at first - now I downloaded it: A starting attempt creates nothing but a shy & short noise like a cricket would produce it.

So yes, all good catches above: The error messages in the video of the S-Type-display are ABS, DSC, low fuel level. apply handbrake.
Error messages from the display are an indication that something is wrong, but they are mostly confusing. An OBDII-code-reader is required now.
Those are meanwhile available from 10-15 AUD$, but they do not always show all the codes - so maybe invest a bit more.

And yes: 15VDC looks fishy, and one idea is to have someone measure WHILE you attempt to start to see, if the voltage collapses.

Having said all this:
Watching the video, and this 15VDC info, I would kind of think that the most likely problem is that your battery is totally dead and that your multimeter is either broken and shows voltages, which are way higher than they are, or (again: more likely) the little battery of your multimeter is way to weak to the effect that is shows now 15VDC, where you may have 9 or 10VDC only in the car battery...

Of course there could be additional complications/failures arising from the new possibly non-compatible seat.

 

Thanks very much for the useful advice. Peter has hit the nail on the head.
1. My multimeter was reading the voltages wrong because its battery was on the way out.
2. The car battery is pretty much dead.
3. Good news - I got it started after buying one of the fancy lithium battery jump starters

Interestingly, I discovered that all the warnings and the gauges going mad were caused by depressing the accelerator down slowly twice as advised after reconnecting the battery. The exact sequence that showed this was:
- engine started fine with jump starter
- I remembered about the accelerator pedal throttle reset
- turned engine off and switched ignition to position II
- pressed accelerator down slowly twice
- warnings came up and gauges needles shot up to max and car would not start
- then I switched ignition off completely and left it for about a minute
- tried to start it again and it started fine. Note the jump starter was still connected.

 

Interesting failure mode on your voltmeter. Typically they show gibberish or the display goes dead. Glad you sorted that out.

Definitely charge the car's poor battery. Don't rely on the alternator to bring it back to life. Have it checked out, too. If it ran down that far, it is probably kaput, beyond a mere recharge. Most auto parts stores will test for free.