My S60 is having starting issues. When I turn the key, I get a click or series of clicks. I keep the key on, or of and on again, the engine will crank over, but the lights dim, enough for the clock to lose it's memory. It will keep cranking at normal speed for a bit, then stop. If I wait a few seconds, turn key again, it will crank/click again, and eventually it will start up and run normally. If I shut it right down, it will start right back up.
A month or so ago, I was just getting single click, so I replaced the battery. It has been fine since then, but not this is happening.
Since it has plenty of battery juice to keep cranking the starter, I am suspecting a bad starter motor that has a large current draw? Possibly enough to keep the electronics from having enough voltage to run and power the ignition, fuel etc?
Do you think dirty connections to the starter could cause this issue?

 

I had a bad ground from my starter to the frame on my old Blazer that caused a very similar issue. Might want to check the ground cable from your battery and starter for corrosion, wear or resistance before spending the $$$ on a starter or busting knuckles taking it out to test it.

 

By the way, this was a bad starter.