So I have a 2005 XC90 T6. It will crank over for literally 3 seconds, then stop. I turn the key back, and go to start again, and the same, cranks for 3 seconds, then stops. It will continue to do this every time, only crank over for 3 seconds then stop. Since I've owned this vehicle it would always start within 3-5 seconds, so it stops cranking right before it would normally start. I'm kind of stumped on this as I've never seen this happen with any vehicle before. I get the message "Immobilizer, See Manual". That's also the first time I've seen that message. I've looked into that, and have narrowed it down to possibly the CEM, but the part that puzzles me the most is how it will crank for 3 seconds and stop every time. I need to get this thing back on the road as my car is my job, so this has been causing quite an issue.

 

Did you check battery voltage? did you try resetting the immobilizer (lock/unlock doors 5x with the fob or key)? I suspect something more pressing may be at play here and you should get a proper diagnosis from a Volvo shop with a VIDA system.

 

Yeah, I tried the whole key fob trick to no avail. The battery is only a few months old. It's just weird that it'll crank over for 3 seconds at a time, and it cranks at normal speed, not slow or anything that would normally indicate a weak battery.