Citroen DS3 HDi 90 Steering Angle Sensor Location

[Intercress]

I have a Citroen DS3 HDi 90 with an ABS/ESP fault, which causes an MoT failure. My iCarsoft CP Max reports a fault with the Steering Angle Sensor. I have been led to believe that the SAS is contained within the Steering Comms Unit behind the steering wheel, the unit with the indicator/wiper/lights stalks attached. I have replaced this unit twice now, but I still get the same error. I dug a little deeper into this and put my CP Max into live data mode from the SAS. When I rotate the wheel to the right, the CP Max shows a decreasing negative number, and no fault. When I start turning to the left, the number increases in value, and then as soon as it passes zero, the CP Max reports the unit switched to Faulty, and the number freezes on whatever value is reached at that point. As an experiment, I disconnected all the wires from the harness to the steering comms unit. There are three connectors, one for the Airbag, and two presumably for the CAN bus. Everything lights up as an error on the dashboard, but I still get live data from the SAS. I have concluded that the SAS is not contained within the Steering Comms Unit. Can anyone tell me where it might be located please? I have checked all the way along the steering column, and nothing. My final conclusion is that it must be housed in the steering rack itself, I can't think where else it would be. This is going to be an expensive repair, so before I undertake it, can anyone verify that my theory might be correct? Thank you

[GiveMeABreak]

Pop your VIN up so I can see what you have.

If you have done any work on the ABS / ESP unit, for example changing it, then the SAS needs recalibrating as the ESP system relies on this being 100% accurate. This is normally done with Diagbox, so I can't speak for your aftermarket diagnostic tool.

Replacing the Comms unit behind the steering wheel will also trigger this fault - once removed it must be recalibrated.

[Intercress]

Hi Marc,

Thank you for taking the time to reply! I'll PM you the VIN number. I have re-calibrated the SAS, which does temporarily fix the problem, until I steer left, then the fault re-appears. I'm absolutely convinced that the steering angle sensor is not located in the steering comms unit, because I've detached all the wires from it, and I'm still getting live SAS data. Additionally, I have taken apart the old steering comms unit, to have a proper look. There's no optical disk encoder, no gears with magnetic hall effect sensors, no potentiometer, absolutely nothing that could even remotely be a steering angle sensor.

[GiveMeABreak]

No Need to PM it to me, our software automatically masks it from public view once you submit your post. Only staff can see it. Please just provide it as is with no spaces.

[Intercress]

Hi Marc, the VIN number is: VF7**************[VIN obfuscated, can be read by forum staff] Thanks again

[GiveMeABreak]

Ok, so on your vehicle uses a specific type of Electric Power Steering, the Torque and Position Sensor are shown below along with an explanation of the components and the working:

(2) Power steering electric motor.
(3) Electric power steering ECU - Torque and position sensor.
(4) Steering wheel.

"a" Power steering electric motor.
"b" Steering wheel torque and angle sensor (Absolute steering wheel angle) (*).
"c" Electric power steering ECU.
"d" Steering rack.

The torque sensor permits continuous measuring of the torque applied to the steering wheel.
The torque sensor determines the following parameters:

• Direction of rotation of the steering wheel
• Torque applied by the driver on the steering wheel

The absolute steering wheel angle sensor is used on vehicles that have ESP (*).
The electric power steering then has the job of sending the steering wheel angle information on the CAN once the engine is started.

Funtion

(1) Pinion stem.
(2) Upper rotor.
(3) Lower rotor.
(4) Hall effect sensors support.
(5) Geneva wheel (*).
(6) Steering wheel angle sensor magnet.
(7) gear.
(8) Torsion bar.

The Hall effect torque sensor has no contact.
The torque sensor located on the pinion shaft is used for measuring, in real time, the torque applied to the steering wheel by the driver (Value of the torque between + 10 Nm and -10 Nm).
The pinion stem (1) is linked to the pinion (7) via a torsion bar (8).

Each rotor consists of an opposition of South/North magnetic poles:

• The upper rotor (2) is solid with the pinion stem (1)
• The lower rotor (3) is solid with the pinion (7)

The torque applied on the pinion stem (1) by the driver creates a torsioning of the torsion bar (8), leading to an angular offsetting of the 2 rotors.
The angular offset of the 2 rotors produces a variation in the magnetic flow which is converted into an electric signal by 2 Hall effect sensors.

For vehicles that have ESP, the torque sensor is complemented by the following specific components:

• Geneva wheel (5)
• 2 Additional Hall effect sensors

The magnetic ring (6) measures the rotation of the lower rotor (3) via 2 specific Hall effect sensors: In this case, the steering wheel angle sensor continuously measures the value of the steering wheel angle during driving, relative to the steering wheel angle on starting the engine (Value of the angle varying from + 360° to - 360).
The Geneva wheel (5) gears onto the tracks of the lower rotor (3) in such a way that it turns 1/10th of a rotation for every 180° of rotation of the upper rotor (2).
The Geneva wheel (5) measures the steering wheel angle on starting.

Calibration
The steering wheel angle sensor must be calibrated in the following cases:

• Adjustment of the tracking
• Change of direction
• Work carried out on the steering column or mounting
• Appearance of the fault "steering wheel angle sensor fault": "calibration of the sensor incorrect", or "sensor never calibrated"

[Intercress]

That is awesome! Marc, you are an absolute lifesaver! I was starting to tear my hair out over this car, and you have just solved it for me. I'm so glad I asked on here now, Thanks again ... Tim

[GiveMeABreak]

No worries.

[Cinncoff]

No worries.

Hello, Mark!

I'm sorry to bother you, but I wonder if you could help us with a similar problem. The VIN number of our car is VF7**************[VIN obfuscated, can be read by forum staff]. Does it use the same steering system, meaning, is the Steering Angle Sensor located on the steering rack itself or does it come with the steering column switch that's underneath the steering wheel?

We've had C1135 Steering Angle Sensor errors ever since our steering rack was repaired and the repair service insists that we need to replace the sensor itself and that it is located under the steering wheel. But your schemes seem to say that the sensor is fixed to the steering rack. Which means it could've been damaged during the repairs in the first place.

Any insight, really, would be greatly appreciated.

[GiveMeABreak]

Hi

It all depends on the vehicle and the type of power steering / engines fitted etc. I have included the specific info as it relates to your DS3 below as there are some differences:

In your case the Steering Wheel Angle Sensor is located in the electric power steering system fitted on the steering rack itself.

If the rack is removed and refitted, the steering wheel angle sensor must be calibrated.

"a" Power steering electric motor.
"b" Steering wheel torque and angle sensor (Absolute steering wheel angle) (*).
"c" Electric power steering ECU.
"d" Steering rack.

In Detail

(1) Pinion stem.
(2) Upper rotor.
(3) Lower rotor.
(4) Hall effect sensors support.
(5) Geneva wheel (*).
(6) Steering wheel angle sensor magnet.
(7) gear.
(8) Torsion bar.
The Hall effect torque sensor has no contact.
The torque sensor located on the pinion shaft is used for measuring, in real time, the torque applied to the steering wheel by the driver (Value of the torque between + 10 Nm and -10 Nm).
The pinion stem (1) is linked to the pinion (7) via a torsion bar (8).
Each rotor consists of an opposition of South/North magnetic poles :
The upper rotor (2) is solid with the pinion stem (1)
The lower rotor (3) is solid with the pinion (7)
The torque applied on the pinion stem (1) by the driver creates a torsioning of the torsion bar (8), leading to an angular offsetting of the 2 rotors.
The angular offset of the 2 rotors produces a variation in the magnetic flow which is converted into an electric signal by 2 Hall effect sensors.
For vehicles that have ESP, the torque sensor is complemented by the following specific components :
Geneva wheel (5)
2 Additional Hall effect sensors
The magnetic ring (6) measures the rotation of the lower rotor (3) via 2 specific Hall effect sensors : In this case, the steering wheel angle sensor continuously measures the value of the steering wheel angle during driving, relative to the steering wheel angle on starting the engine (Value of the angle varying from + 360° to - 360).
The Geneva wheel (5) gears onto the tracks of the lower rotor (3) in such a way that it turns 1/10th of a rotation for every 180° of rotation of the upper rotor (2).
The Geneva wheel (5) measures the steering wheel angle on starting.
N.B. : (*) According to version.

The steering wheel angle sensor must be calibrated in the following cases:

• Adjustment of the tracking
• Change of direction
• Work carried out on the steering column or mounting
• Appearance of the fault "steering wheel angle sensor fault": "calibration of the sensor incorrect", or "sensor never calibrated"

Fault Code

Fault Code:	C1135
Description of Fault:	Steering wheel angle sensor signal fault. Steering wheel position sensor fault. At least one of the following conditions must be fulfilled: - Vehicle stopped (The ignition is on and the engine is not running) - Vehicle in motion
Conditions for Fault to clear:	Ignition switched off and on again
Downgrade Modes whilst Fault is active:	Reduced performance Deactivation of the function for return of the steering wheel on a bend, as well as of the function for detection of the full locks (Driveability strategies)
Symptoms:	Deactivation of the function ESP Possible noise at full lock Sticking sensation
Suspect Areas:	Steering wheel’s angle sensor (Internal to the electric power steering)

[Cinncoff]

In your case the Steering Wheel Angle Sensor is located in the electric power steering system fitted on the steering rack itself.

Thanks a lot, this is extremely helpful! You're simply the best!

[Duffy]

Hi we're having this issue too
Would you mind checking my vin number too please
VF7**************[VIN obfuscated, can be read by forum staff]
Would be really appreciated