Steering Angle Sensor: Service and Repair
Removing And Installing Steering Angle Sensor
- A steering angle sensor -C- is attached to the steering column/steering shaft for PSM (Porsche Stability Management) in the 911 Turbo.
- Cover -D- remains fitted during removal and installation of the steering angle sensor.
- Removal of cover -D- is generally not permitted.
A - Universal joint of steering shaft
C - Steering angle sensor. Modified versions as of 2003 model; refer "Notes on replacing the steering angle sensor - vehicles prior to '03 model".
D - Cover
Notes On Steering Wheel Position During Removal And Installation
- Lock the steering wheel and the front wheels in a straight-ahead position. Make sure that this position is retained for reinstallation. Refit in the same position during installation.
- If this is not done, the airbag contact unit (spiral spring) can be damaged. Also, the steering wheel can be crooked when the front wheels are in a straight-ahead position after the steering angle sensor has been installed.
Removal
1. Remove driver's seat.
2. Switch ignition off.
3. Remove air duct.
4. Turn front wheels to a straight-ahead position. Fix the front wheels and the steering wheel in this position.
5. Undo hexagon-head bolt on universal joint -A-. Detach universal joint -A- from the upper steering shaft and push into the lower steering shaft (-direction arrow-). Disengage cable guide -B- in the direction of travel.
A - Universal joint of steering shaft
B - Cable guide
C - Steering angle sensor
D - Cover
NOTE: Pull at the plug housing only. Never pull the electrical connections.
6. Pull off steering angle sensor plug. The plug can be pulled off to the side -direction arrow- or to the front (depending on the design of the steering angle sensor). Disengage steering angle sensor -C- to the front. To do this, press carefully on the sensor (-direction arrow-) through the opening in cover -D-.
Notes On Replacing The Steering Angle Sensor - Vehicles Prior To '03 Model
A new steering angle sensor -C2- is installed as of the 2003 model (3-programme). This internally modified steering angle sensor, -C2-, differs (externally) from the previous steering angle sensor, -C1-, in having a larger plug connection that is also located in a different position. New steering angle sensor -C2-: axial plug connection (below steering shaft)/previous steering angle sensor -C1-: radial (lateral) plug connection.
- When a replacement is required, new steering angle sensor -C2- can be retrofitted in place of the previous version, -C1-.
- When new steering angle sensor -C2- is installed in vehicles prior to the 2003 model, new cable guide -B2- (instead of the previous cable guide) and adapter lead -E- must be installed because of the modified plug connection (larger plug, position of plug and modified plug assignment).
- The main difference between the old cable guide, -B1-, and the new cable guide, -B2-, (implemented as standard as of the 2003 model) is the cable deflector at the end of the cable. There are interruptions (openings) in the cable slot (ribs) of new cable guide -B2- for routing the lead (there is no open circuit in the ribs in the old cable guide -B1-).
- Adapter lead -E- is inserted (fitted) between new steering angle sensor -C2- and the existing (previous) lead, -X-. The leads that are joined together, -X and E-, are then inserted with the plug connection into the cable slot of new cable guide -B2- and secured with a tie-wrap -arrow-.
NOTE: Before inserting leads -E and X- into the cable slot, fold them so that the leads lie directly above one another and are correctly positioned.
Component Overview
Pin assignment of adapter lead -E-
Pin 1 - 4:
Installation
CAUTION:
The airbag will not function if the spiral spring in the airbag contact unit is damaged. Observe mounting specifications.
- Avoid uncontrolled twisting of steering wheel in the wheel position (by turning the steering wheel when the universal joint is being removed on the steering shaft). This means that if the steering wheel is turned to fit the steering angle sensor1 the same steering wheel position, and thereby the position of the spiral spring in the airbag contact unit, must be re-established before fitting the universal joint.
- The front wheels, steering wheel and airbag contact unit must be positioned correctly in relation to one another before the universal joint is fitted on the upper steering shaft, i.e. they must be in the same positions that they were in before the removal (the steering wheel and spiral spring are positioned centrally and the wheels are in a straight-ahead position).
NOTE:
- The steering angle sensor and its hub adapter must engage audibly.
- Use a new fastening screw on the universal joint Observe the tightening torque of the screw.
- When replacing the steering angle sensor in pre-2003 vehicles, ensure that the components in the surrounding areas are correctly assigned (this is determined by the steering angle sensor version that is used).
- The steering angle sensor has no defined zero position when new. The position for "straight ahead" direction of travel must be programmed. This is done by calibrating with the Porsche System Tester, when the wheels are in a straight-ahead position, on the measuring station.
1. Secure the steering angle sensor to the steering column (steering shaft) 'in 2 stages'. 'Stage 1:' Secure (engage) adapter -1- to the steering shaft. 'Stage 2:' Fit steering angle sensor to adapter -1- (detailed instructions on how to do this will follow).
1 - Hub adapter
2 - Driver for steering angle sensor
3 - Internal locking tab (for securing to the upper steering shaft)
4 - External locking tab
5 - Engagement (cutout) on the driver
Detailed instructions:
- First, disengage hub adapter -1- from driver -2- of the steering angle sensor -engagement 5- and pull it out.
- Push hub adapter -1- onto the steering shaft. Locking tabs -3 and 4- must be facing the steering wheel. Internal locking tab -3- must engage completely in the cutout in drive shaft -6-. Check that it is fitting securely: hub adapter -1- must not be able to twist on the steering shaft. In order for the cutout in steering shaft -6- to be visible in the opening of cover -D-, twist the steering wheel out of its original position beforehand. Then return the steering wheel to its original position.
- Push steering angle sensor -C- across the hub adapter that has already been fitted. The driver of steering angle sensor -2- is facing the steering column. External locking tab -4- in the hub adapter must engage completely in the driver engagement. In order for locking tab -4- to be visible in the opening of cover -D-, twist the steering wheel out of its original position beforehand. Then return the steering wheel to its original position.
NOTE: If the steering wheel was not secured before the steering wheel sensor was removed or if the steering wheel was twisted when the steering angle sensor was fitted on the steering shaft, the contact unit (spiral spring) may no longer be in the correct position. If this is the case, remove steering wheel and move contact unit to centre position.
2. Secure steering shaft (universal joint) -A- in correct position - the same position that it was in before the removal (wheels are in a straight-ahead position, steering wheel and spiral spring are in a central position) - to the upper steering shaft.
3. Push plug onto steering angle sensor (plug in cable) and engage cable guide -B-. Install the new cable guide with the adapter lead only when modified steering angle sensor version C2 is used for the first time in vehicles prior to the 2003 model (see following procedure).
Conversion - new steering angle sensor in vehicles prior to the 2003 model
When converting from the old to the new steering angle sensor design, -C2-, new cable guide -B2- and new adapter lead -E- (large plug on steering angle sensor) must be installed instead of the old cable guide and previous lead (small plug on steering angle sensor). To do this:
- Fit new cable guide -B2- (engage on the steering column) and insert adapter lead -E-.
- Plug in (engage) the large plug on adapter lead -E- to new steering angle sensor -C2-.
- Join together the plug from existing lead -X- and the plug from adapter lead -E-.
- Insert existing lead -X- and adapter lead -E-, together with the plug connection, into the cable slot and secure with a thin tie-wrap -arrow-. Before inserting the leads into the cable slot, fold them so that the leads lie directly above one another and are correctly positioned.
4. install air duct.
CAUTION:
Malfunctions in the PSM control range if the steering angle sensor is not calibrated or is calibrated incorrectly.
- The steering angle sensor has no defined zero position when new. The position for "straight ahead" direction of travel must be programmed.
- Calibrate steering angle sensor using the Porsche System Tester with the wheels in a straight-ahead position on the measuring station.
5. Calibrating steering angle sensor.