Last night I had a problem braking my Cayenne S (regular suspension, no off road package). It was slippy with snow and I still had the all-seasons on, so on the way home I engaged the center differential (one click). Traction was notably improved. (Before this I could easily get it 'sideways'). Then I tried to stop.

Good thing the road was quiet because the brakes were almost non-functional. The pressure to depress the brake was harder than I could press. I put the vehicle in neutral, switched off the center-diff, put back in drive, and the brakes started working again.

Since no one was around I tried this a couple more times and could not get it to happen again.

Goes in for first service tomorrow, so timing is good. First problem I've had.

Any ideas?

Thanks
Keith