Saturn Saturn ASTRA Specifications download pdf (Page 22)

Chassis Specialist : Electric Power Steering

Page 19

Koyo System Initialization

On the Koyo system, the PSCM is serviced separately, all other components are serviced as an

assembly.

If the vehicle comes in with a steering complaint refer to the Delphi chart above for information with

the following exception: To test the Koyo system for a clunk, rattle noise or vibration at low speeds,

remove the 60 amp EPS fuse—usually located in the under hood junction block. Drive the vehicle in

the same manner to try and duplicate the concern. If the noise is still evident, the cause of the

customer’s concern is in the steering column. By removing the EPS fuse the motor has no power so the

noise heard can only be from the steering column or intermediate shaft. If the concern is only detected

every 90 degree of steering rotation, then the intermediate shaft is binding.

Whenever the PSCM or steering column is replaced the torque sensor and/or the steering position must

be calibrated. While it is not necessary to calibrate the sensors after an alignment, a customer may

complain about poor “on centre feel”.

Torque Sensor Calibration

As there is no steering assist when performing this procedure it is recommended to slightly raise the

vehicle off the ground.

1. Install a scan tool

2. Turn ON the ignition with the engine OFF

3. Build the vehicle and from the steering system select the special function menu

4. Highlight and select the Steering Position/Torque Sensor Calibration and press the enter button

5. Centre the steering wheel

6. Now turn OFF the ignition and remove the ignition key from the cylinder

7. Wait 29 seconds before inserting the key and turning the ignition ON with the engine OFF

8. Turn the steering wheel 180 degrees to the left of centre and hold it there briefly

9. Now turn the steering wheel 180 degrees to the right of centre and hold the steering wheel

briefly

10. Return the steering wheel to the centre position. Verify the steering wheel is centred and there is

no force being applied to the vehicle’s suspension and steering system

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Saturn Saturn ASTRA Specifications Page 22