I've been having an intermittent problem starting my '92 200TDi Disco for a little while.
It behaves as though the battery is flat and won't turn over the engine. Taking the key out then trying again will often fix the problem. Most times this will be from a cold start, but it will sometimes start fine in the morning, then fail to start after a short journey. Now, the preheat light sometimes fails to come on.
I've checked the battery, the alternator and the starter motor and they all seem fine.
Does anyone have any ideas what the problem may be?