996 TT ABS Kicks in on right turn braking

[fredkhaz]

Hello everyone,

I just picked up a 996 TT with 88,000 miles on it (90k service was just dont $3k), replacing my 996 C2 with 181,000 miles on it.

the ABS (passenger right corner) kicks in when i apply brakes when making a long right right turn. it feels that the brake paddle pushes back up also.

I think i felt the same thing in my 996 C2 once or twice before but with the steering wheels was turned almost all the way left or right.

Any idea ???

Now today i noticed that the PSM light comes on when that happens.

Edited September 24, 2010 by fredkhaz

[RFM]

I would check the tires first, general condition, brand, dimensions, etc. and if possible, use the wheels of a similar car and do a test drive.

[wvicary]

Also clean the wheel speed sensor for that wheel and wheel brng for excessive movement. Metal swarf can collect on the magnet and alter it's output which can cause false triggering of the system.

[Danyol]

Are the wheels/tires non std sizes? Fron and rear tire compound missmatch caused similar problems for me.

[tbarcelo]

Danyol,

Can you elaborate?

I bought my 2003 Turbo last April and it came with 997 wheels with "incorrect" tire sizes - i.e. 235-30-19 fronts and 305-30-19 rears. Michelin PS2s up front and Hankook Ventus V12s in the rear. Other than an alignment issue that caused severe wear on the rear outside edges, I didn't have any PSM problems. When I corded the Hankook, I decided that it was time to fix my "incorrect" tire size issue, so I went with the recommended 315-25-19 tire in the rear to match the diameter of the 235-30-19. At the same time, I corrected my toe problem and slight driver's side rear camber problem.

Immediately, I got the same behavior as described in this thread. PSM interference with long sweeping on/off ramps at modest speed. I will definitely check the speed sensors, but I'm currently concerned about my whole wheel tire package. Suggestions?

[Danyol]

tbarcelo,

I went through a very similar experience with the tire sizes and mismatch tread.

When I bought my car it had the 235/305 combination on Pirellis. No issues with PSM but tire size calcs showed the 315-25 to be the better match. Didn't take long with the "chewing gum" Pirellis, I needed to replace the rears. I went for the Toyo T1R in the 315, immediately had problems with PSM kicking in on sweepers. I had maybe 5k left on the fronts, I ditched them for matching T1Rs. No problems after that, no issues with psm for over 15k now (yep, they still have a lot of tread left!).