Hello all-

I'm having an issue with PSM in that it errantly hard brakes a wheel (front right or left) for about .5 seconds when going thru a turn. It happens most often when going moderate speed thru a turn, but not racing speed, not even close to pushing the limits of the car. Only been tested on dry pavement. When this happens, the PSM light does come on for that ~.5 second of ABS pulsing that wheel. It brakes that wheel so hard that that tire has streaks going diagonally across it from scraping on the road. It seems to happen at speeds between 30-60, although I have not tried to get it to do it at faster speeds.

I have a 2004 996 C4S in beautiful factory condition, 50,000 miles. No mods other than LED 3rd row brake lights and an iPod integration with the factory Nav/Bose system.

This started to happen right after replacing the rear tires (they were bald on the inside yet fronts are at roughly half life). I replaced the rear tires with the same that was on the car. I'm running Hankook V12 Evo in stock sizes (225/40-18 front and 295/30-18 rear). Another fact is that the tires were replaced at the same time the AOS was replaced, which did require lowering the rear of the engine by about an inch during the repair as well as taking off one intake manifold.

I've had no PSM/ABS issues ever. The car has been flawless. It is not tracked or driven hard. Alignment and tire balance seem fine. The third row brake lights were placed about two years ago to LED versions, and no issues from those.

My local independent Porsche shop which did the AOS and tire replacement has no idea. They've test driven it and checked for error codes, of which there are none. Next step is the Porsche dealer in town, which I've spoken with their head mechanic and he has no idea nor heard of anything.

Any of you have any ideas? Thanks,
KC