Hello. I think it best I describe what is happening.
1997 Discovery 300 tdi.
Occasionally the starter refuses to play. If I keep trying the key it eventually wakes up and starts.
Here's the weird bit.
When it doesn't want to play the relay can be heard clicking in but only when the drivers door is open. If I close the drivers door and the interior light goes out then the relay stops clicking. I was thinking it was a sticking solenoid on the starter, but since I have discovered the door switch thing I am not sure.
Is this going to be a poor earth that needs to be chased down?

Thanks in advance