Cables and grounds have some history of problems. Some info here may help you. Good luck. vic2008 Diesel Sprinter - only 30K miles. Thought battery was bad - replaced it this morning. When you turn the key to start it just clicks - one time. Have also tried jumpers. Any ideas? Thank you Wayne
There is a lockout feature built into the key turn for start. Once the key is turned from off to start it will not request start again until cycled to off. That is to prevent the operator from grinding the starter gear if the engine is already running.I tested the headlights lights like you said. When initially trying to start - they dim for an instant when I hear the starter or solenoid click. If I try to start again without completely recycling the key they do not dim and I hear no click. Thanks for your ideas.
The start relay is a special high capacity design with large blades. Unless things have changed from the T1N it is a one of a kind special purpose relay that has no similar relay anywhere in the Sprinter. That said, I'm not familiar with the NCV3 as I don't own one.
Not that anyone asked...
I'd put my efforts into checking the cables before going through starter removal. The starters are generally very reliable. You did indicate 30,000 miles. vic