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Porsche 997 Turbo PASM failure intermittent

Killer-M | On 08, Jun 2013

Porsche 997 Turbo PASM failure intermittent

About a month ago I had the PASM failure light come on my Porsche 997 Turbo, this switched the control unit off essentially turning off all the suspension management systems – as one would expect. I switched the car off, restarted it and everything was fine.

After a few weeks of solid driving, the error came on again this morning. The same remedy was applied… switch off and switch back on.

I’m curious if anyone has had this experience? It seems like a very odd and almost impossible to diagnose the problem (if it is a problem).

The main issue in diagnosing this that the regular OBDII cable (that most Porsche enthusiasts own) can’t read PASM error codes, and apparently on restart of the car the error is no longer there. So the only alternative would be to drive into the shop when it does come on (which is a tall order – well not that tall but an inconvenience).

The other strange thing is in my experience when the PASM fails generally the control unit needs to be replaced, and the error remains there permanently.

Curious if any one has had the same issues.

With reference to my car, it’s a 2007 Porsche 997 Turbo. The suspension has been updated with Bilstein B16 DampTronic Coilover Suspension kit  (together with many other RSS suspension goodies, but they shouldn’t have any affect on this error in particular).

 

PASM-failure-porsche-997-turbo-8053 fault-with-locking-steering-column

 

The PASM 8053 Fault With Locking Steering Column Failure:

As it turns out the failure occurs due to a 8053 error code, which indicates a problem with the locking mechanism in the steering column. Both myself and the tech were a little stumped so now it’s a wait for the experts to get back to us to try to reach resolution with this.

Another diagnosis of the problem is that if the car is switched off and the steering lock is not engaged (by moving the wheel around with the key out of the ignition) the PASM error appears as soon as the car is moving. If the lock is engaged between stop and start the error disappears… well at least for a few days or weeks.

Strange or what…

The steering angle sensor calibrated after having your suspension alignment changed

After further consideration, after this error occurred, it could be the steering angle sensor which needs to be calibrated after having your suspension alignment changed. It’s all critical to the proper functioning of the PSM.

The steering angle sensor of the 911 Carrera must be initialized or calibrated after the work below has been carried out.
Initializing – following each interruption of the Terminal 30 power supply
Calibrating – following any work on the vehicle (e.g. suspension alignment, change of parts)

porsche-997-steering-sensor
The steering angle sensor (arrow) consists of an optical segment sender and a code disk, which are integrated in the steering column switch. The light emitted by the segment sender is interrupted by the inner ring in a specific sequence resulting in 5 segments with 72° per revolution. The outer ring is set up to cause interruptions of varying length from which the system can calculate the exact steering angle. The data measured in the integrated micro processor is sent to the PSM control unit via the CAN bus.
The PSM control unit thus receives the information on the lock angle of the front wheels (driver intention with regard to direction of travel). This signal is used inside the PSM control device to determine the optimum vehicle behaviour with regard to its longitudinal dynamics through offsetting the speed of travel.

 

Testing and Inspection, From Porsche Service manual

WM 456000 Initializing and calibrating steering-angle sensor

General warning notes

Caution
Increased risk of accident when ever power supply is interrupted. PSM does not function.

The steering-angle sensor must be initialized (taught) whenever the battery is disconnected.

Note

  • The steering-angle sensor is integrated into the steering column switch and records the movements of the steering wheel (steering wheel angle) using light switches. The data is transmitted to the PSM control unit via the CAN bus.
  • During initialization, the steering-angle sensor learns its current position (straight-ahead position).
  • The steering-angle sensor must always be initialized if terminal 30 was interrupted (for example, battery replacement, undervoltage, steering column switch disconnected, relevant fuse removed)!
  • Calibration must be performed when working on or carrying out subsequent work on the chassis.
  • The calibration results in zero point balancing (exactly straight ahead).
  • The steering angle sensor is calibrated when first fitted and when any work has been carried out on steering and chassis. Examples of this would be opening the steering wiring and alterations to toe and camber.

Calibration includes initialization.

Checking steering-angle sensor

Initialize steering-angle sensor

  • Turn wheels to straight-ahead position.
  • Start engine.
  • From the straight-ahead position, turn steering wheel approx. 20°to the left and 20°to the right (past straight-ahead position).
  • Drive the vehicle straight ahead for at least three seconds at a speed above 6 km/h (3.7 mph) . After successful initialization, the stored fault code is erased from the fault memory. The PSM indicator light in the instrument cluster goes out. After initialization has been completed, the battery must not be disconnected, the relevant fuse must not be removed and there must not be undervoltage. Otherwise, initialization will have to be carried out again.

Adjusting steering-angle sensor

Calibrating steering-angle sensor

Note

  • The steering-angle sensor must be recalibrated on the measuring platform following repairs to or work on the chassis/steering or if the steering-angle sensor/steering column switch/hydraulic unit is replaced.
  • Calibration includes initialization.
  • In order to be able to calibrate the steering-angle sensor correctly, the vehicle must be on the measuring platform, the wheel alignment values must be correct and the steering must be in the straight-ahead position.
  • To calibrate the steering angle correctly, the PSM control unit must first be coded successfully (e.g. after replacing the hydraulic unit).
  • The safety code is displayed under >> PSM >> Actual values << in the Porsche System Tester. Please take note of this code for future use.

The steering angle sensor must be calibrated using the menu with PIWIS tester under the specified test conditions:

  • Switch on ignition.
  • Turn wheels or steering wheel to straight-ahead position. In the straight-ahead position, the steering wheel must deviate by no more than ±2.0° from the horizontal position (steering center position).
  • Before calibrating, first turn the steering wheel from the straight-ahead position approx. 20°to the left and 20°to the right (past straight-ahead position).
  • Turn wheels or steering wheel to straight-ahead position and calibrate the steering-angle sensor. To calibrate, you must enter the security code in the actual values menu.

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