I have an issue that has perplexed me. I have a 2003 Jaguar X-type, 2.5L. It has a new battery (less than 6 months old). In the last 2 days, when the car has been driven on the highway for approximately 40 miles at roughly 70 mph on both occasions and the ignition turned off, the car would not start when the ignition was re-engaged (after a minute or two). No dash lights or warning lights would come on (nor the radio/clock, etc.). Both times I opened the hood and checked the battery leads and shut the hood. Nothing seemed amiss. However the car started up immediately both times, but the clock reset (but the preprogramed radio stations were still correct). On both occasions I had driven the car around town (both before and after this issue) without incident. It appears to occur only immediately after the car is turned off after a long highway trips (not around town). Because the clock reset (as if it lost battery current), I would think it has to do with the battery, but the battery and alternator seem to work fine. Another issue, although I believe unrelated is when I've been gone 4-5 days and the car has sat in the garage. On 2 occasions, when I started it, the red battery indication light illuminated (although the car drove fine). When I turned the car off, the battery light went out and didn't reappear when I later drove the vehicle. These seem to be different issues, but tough to pin down.

 

It sounds to me like the cables are going. Can you check for voltage drop along the cables? Check ground connection. Possibly the joint of the positive cable to the connector? Does either cable feel hot when the problem occurs?

 

When the car won't start, can you describe what happens, for example:
+ Any noise from the starter motor?
+ Any click sound / vibration from the starter relay (it's in the black box next to the battery)?

Some things to check and try:
+ When it runs, does the alternator generate sufficient voltage to fully recharge the battery?
+ When it won't start on it's own, will it jump start with cables from another car?
+ Clean the connections between the battery cables and battery posts
+ Clean the connection between the negative battery cable and the chassis ground (under the battery, behind the headlight)

 

 

I haven't checked heat of the cables, but will try that.

 

When the car won't start there is nothing. No noise, no "idiot" lights on the dash, no clock display. The engine doesn't even attempt to start. It's as if the battery is dead (no connection). But then it starts.

 

dembitz1: Have you made progress diagnosing your battery & starting issues?

If "no", try cleaning the battery posts and battery cable connections - an easy place to start. Disconnect the cables from the battery and clean the posts and insides of the clamps with a wire brush and / or fine sand paper - rolled in a tube to get inside the cable clamps.

Also, try cleaning the ground connection where the negative battery cable bolts to the chassis. Follow the negative cable to where it bolts to the chassis under the battery and behind the headlight. Unbolt this connection and lightly sand the connector and under the head of the bolt.

If you do this and the problems persists, you'll want a voltmeter to check the fuses and relays in the two black boxes next to the battery to see where the 12 volts from the battery are not getting thru to the dash components, ignition switch, starter, etc.

The good news is, since you're getting no power anywhere in the car, the problem is likely early in the electrical system, I suspect in the fuse & relay boxes next to the battery, if not the battery post connections or battery ground connection. The bad news is that the problem is intermittent, making it harder to replicate and isolate.

Please keep us posted on your progress.

 

Please check the + cable that runs low under the battery box and into the bottom of the fuse box. It may look fine from above but, it runs across a body bolt and the insulation can wear on the bottom side causing it to contact the metal. Found mine when it actually arced and started to smolder.