I have experienced this problem twice now . . . this morning while working on the car to replace the regulator in the driver's door, after putting everything back together, the car would not start . . it attempted to start, the speedometer and tachometer pegged to the max reading, lights started to flash and car alarm went off. It kept doing this on several attempts, so I hooked up my other vehicles battery to the Jag and attempted to start it again. Same thing kept happening. I finally sat in the Jag, jumper battery still hooked up, closed the driver's door this time, and the Jag started right up. I can't believe the battery drained down while working on the driver's door because when you disconnect all the harnesses, no interior lights are on. Any ideas??

 

If it is the battery. You have to take into consideration that when your door is open, about 6 or more lights are on as well. Also your cluster guage is on as well when you turn the ignition into the next step. The battery might also need its cells replenished (see owners manual). As for using your other vehicle's battery,you do realizecar batteries varyin terms of amp and cold crank start right?

 

Checked battery w/voltmeter . . . 12.2 volts at rest . . . started vehicle and 13.7 volts at idle . . . alternator seems ok . . have to figure out if this battery is a sealed one or if I can replenish w/distilled water . . . was in vehicle when I bought it a month ago . . after idling for maybe 5 minutes, battery now at 12.4 volts at rest . .

 

The cells are your problem

 

Battery in an Interstate Mega Tron Plus 1000 CCA - best they carry . . . cells were on low side, plates were still covered . . filled with distilled water . . will keep eye on it and see if it recharges itself . . .[X(]

 

You could have the battery tested, most auto parts stores will do it for free. It takes about an hour. I took mine to kragens and they told me it was bad.

 

Had battery checked at local Interstate Battery place . . 750amps (should be over 850), hydrometer showed cells low on charge . . . told me I need to drive car more (haven't driven much since I bought it a month ago) or put a trickle charger on it for a day or two to bring it back up to par . . overall the battery tested ok . . .