Hi, everyone, I have a weird and frustrating problem with my 2002 XKR convertible, which I have had for 7 years and done 40k miles in - (total mileage is now 130k) -
Every so often I turn the ignition key and get either nothing - no lights, nothing!- or the ignition lights and pre-check all seem ok but no starter activity when key is turned. Then, out of the blue it is suddenly ok again - Occasionally it has entailed me going into the battery compartment and tapping connections, which seems to no avail, yet suddenly power is restored and I'm not sure if it is anything I've done or not! For example yesterday I caught it completely dead, couldn't open the doors or boot lid with the key, so I thought if I could monitor everything I did I could get to the bottom of it. I pulled and tapped away at the wires and terminals and the main earth point (all of which have been off and thoroughly cleaned) and got nothing, then all of a sudden I touched another earth point on the body (next to the main one) with a wire attached to the battery earth and the boot lights came on, meaning the car was ready to start again! I didn't hold the wire on after the lights came on, and I didn't really touch it hard enough to have displaced anything, so what is going on?
As a secondary aspect of the same problem, I have had a frustrating time having to keep resetting my windows, sometimes more than once on the same journey, and every now and again my trip meter has zeroed itself, I didn't' connect the dots at first but now I realise there must be regular breakages in the connections somewhere! Of course, intermittent faults are hard to diagnose but has anyone had a similar problem or can advise a likely solution please?

 

Rather than tapping you should be using a voltmeter to test the earth connections. Make up a long +ve meter lead and connect the negative meter lead to the lead of the battery terminal.
Then touch the +ve meter lead to what should be earthed (ign ON) If it reads less then 0.3v the earth is ok ..if it reads 12v the earth is faulty.
If there is a wire to a terminal it could be worthwhile to stab the wire as well in case its not connected to the terminal ( a double ended pin chuck with a needle in it is best)

ebay item 355215811561 pin in one end probe lead in the other ..tape up the middle bit.

 

Thanks, that is useful information to supplement my "experimental" approach to car electrics! In the meantime I have just been tapping again (sorry!) and managed to ascertain that the battery earth connection at the body, despite having previously been cleaned, sanded, polished with a wire brush on a Dremel and put back tightly, seems to have been the cause after all, as the tap with the hammer has just brought it back to life!
This might not be the end of the saga, needless to say!
Fingers crossed!

 

The battery/earth cable has been reported as a fault on several occasions.

 

Sounds like a failure of the joint between cable and the eyelet on the end ....Cut it off and solder a new one one or go buy a new cable from Halfrauds,