2004 XJR supercharged (husband's toy) bought last fall. Left us stranded across town after leaving the aux on while i went in a store for 15 minutes and he had the radio on in the car. Since then, i've had to boost him with my Nissan Sentra a few times. Last week he dropped our son off at work, turned off the ignition, came back out 5 minutes later, car was dead..just a click sound as he turned the key. He phoned me, i came out with trusty Nissan, he started the Jag as i pulled in. A few days ago, car in our garage, he went to start it up...dead. We took my Nissan shopping, came back, he tried the Jag and it started again. Battery says fully charged each time this happens. Last night, jag left him stranded, needed a boost (he didn't call me) I suggested the alternator. This morning, he said the tester mentioned alternator. Anyone else have similar issues?

 

Could be either one- or something else. Rather than guessing or 'shotgunning' the issue by throwing expen$ive parts at it, measure the system voltage with the engine running and with the engine stopped. Measure the system voltage again several hours after the engine is stopped.

BTW letting the battery run down till it's almost dead then boosting it puts tremendous strain on the entire system and will likely damage the battery permanently.

What part of Ontario are you in?

 

We're in Owen Sound Mikey

 

Now it's gone from bad to worse. Battery is showing fully charged, and the jag refuses to start at all.

 

OK, it won't start, but does the starter turn the engine over ? Sometimes you can have a good battery but a bad starter. When I had a Series 3 XJ, the starting got worse and worse, until I put on a new battery, but the problem continued until I replaced the starter motor.

Bad starter motor is not a common fault on this forum. When the engine is started, the electronics boost the battery up quickly by allowing the alternator to provide a higher voltage. After a few minutes running, it reverts to the normal output voltage.

My advice is to get the car to an experienced auto electrics shop.

 

How are you determining this?

 

He has a battery charger that shows the amps, and digitally displays if it is fully charged. He also took the battery from his 2005 Chrysler crossfire convertible and tried it,still nothing. Engine used to turn over, but now nothing, doesn't turn over. Panel lights up, hears a click but no turn over.

 

It's not the battery or alternator then.

 

I did a bit of digging in here and went on a scavenger hunt in the jag for the inertia reset switch. He found it, pressed it, tried starting..nothing but a few loud clicks and dings. He plugged the battery charger in and said let me know when it reads "start engine" (he wasn't optimistic because he'd tried a half hour before i came out and told him about resetting the inertia. 90 seconds,"start engine" came on display, he turned it over and she fired up. He tested the alternator and the display said "good voltage" Beautiful car but now he's afraid to take her out for fear she'll leave him in a parking lot.

 

If you're getting clicks/ticks, but all the electronics are coming on with no prob, it's more than not, the starter. Can you tap it a few times & try to start it? (& the "it starts sometimes, so how can it be the starter" question,,,,,,, trust me,,,,I was just there literally)

 

Good News!! it turned out to be the battery. The one in the jag was original to the car (2004) so it really didn't owe us anything. Got a new one ordered in at Canadian Tire and the jag just roars to life. Thanks all I drove it for the first time last night, what a difference between the jag and my Nissan. Rides similar to my chev caprice classic i had many years ago (V8)...big, comfy and just floats.