C1259
C1259Component Location:
General Description
The Steering wheel angle sensor uses two sensors (A-sensor and B-sensor) to determine the direction of the rotation. The main components of each sensor are LED, photo transistor and slit plate. The slit plate, which has 45 holes, is installed between LED and photo transistor, and generates signals if slit plate rotates according to the steering wheel rotation. The sensor signals are generated by photo transistor which is driven whenever the light passes through the holes. The HECU detects operating speed and direction of the steering wheel by this input signal, and this signal is used as input signal for anti-roll control.
DTC Description
The conformance of the yaw rate, lateral acceleration and steering angle signals dynamic is monitored by comparison of the signal shifts during curves. The function is started when a curve is detected after driving straight ahead for at least 1 s. A curve is detected if 2 of the 3 signals exceed the following thresholds : (1. [Filtered yaw rate] > 4.0 °/ s, 2. [Filtered lateral accel.] > 0.15 g, 3. [Filtered steering angle] > 1.0 °) Due to the varying timing of signal changes, integrators are used to accumulate the signal's deviations from straight ahead driving. The signal changes are integrated separately. The integrated values are compared after a settling time of 2 s.
DTC Detecting Condition:
Schematic Diagram:
Monitor Scantool Data
1. Connect scantool to Data Link Connector (DLC)
2. Engine "ON".
3. Turn the steering wheel to the left or right.
4. Monitor the "STEERING SNSR" parameters on the Scantool.
5. Whenever steering wheel is turned, is the steering sensor's scantool data changed HIGH/LOW?
YES - Fault is intermittent caused by poor connection in steering wheel sensor harness and/or HECU's connector or was repaired and HECU memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.
NO - Go to "W/Harness Inspection" procedure.
Terminal and Connector Inspection
1. Many malfunctions in the electrical system are caused by poor harness (es) and terminal condition. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?
YES - Repair as necessary and then go to "Verification of Vehicle Repair" procedure.
NO - Go to "Power Circuit Inspection" procedure.
Power Supply Circuit Inspection
1. Ignition "ON" & Engine "OFF".
2. Measure voltage between terminal "2" of the steering wheel angle sensor harness connector and chassis ground.
Specification : Approx. B+
3. Is the measured voltage within specifications?
YES - Go to "Ground Circuit Inspection" procedure.
NO - Check for open or short to GND in steering angle sensor harness between terminal "7" of the HECU harness connector and terminal "2" of the steering angle sensor harness connector. Repair as necessary and then go to "Verification of vehicle Repair" procedure.
Ground Circuit inspection
1. Ignition "OFF".
2. Disconnect steering wheel angle sensor connector.
3. Measure resistance between terminal "3" of the steering wheel angle sensor harness connector and chassis ground.
Specification : Approx. below 1 ohm
4. Is the measured resistance within specifications?
YES - Go to "Signal Circuit Inspection" procedure.
NO - Check for open or short in steering wheel angle sensor harness between terminal "3" of the steering wheel angle sensor harness connector and terminal "5" of the HECU harness connector. Repair as necessary and then go to "Verification of vehicle Repair" procedure.
Signal Circuit Inspection
1. Ignition "ON" & Engine "ON".
2. Turn the steering wheel to the left or right.
3. Measure signal waveform between terminal "3,28,30" of the HECU harness connector and chassis ground.
Specification : High : 2.7-4.4 V, Low : 1.1-2.3 V
4. Is the measured signal waveform within specifications?
YES - Substitute with a known-good HECU and check for proper operation. If problem is corrected, replace HECU and then go to "Verification of Vehicle Repair" procedure.
NO
- Check for open or short in steering wheel angle sensor harness between terminal "1,4,5" of the steering wheel angle sensor harness connector and terminal "3,30,28" of the HECU harness connector. Repair as necessary and then go to "Verification of vehicle Repair" procedure.
- If OK, Go to "Component Inspection" procedure.
Component Inspection
1. Ignition "ON" & Engine "ON".
2. Turn the steering wheel to the left or right.
3. Measure signal waveform between terminal "1,4,5" of the steering wheel angle sensor harness connector and chassis ground.
Specification : High : 2.7-4.4 V, Low :1.1-2.3 V
4. Is the measured signal waveform within specifications?
YES - Fault is intermittent caused by poor connection in steering sensor harness and/or HECU's connector or was repaired and HECU memory was not cleared. Go to "Verification of Vehicle Repair" procedure.
NO - Substitute with a known-good steering wheel angle sensor and check for proper operation. If problem is corrected, replace steering wheel angle sensor and then go to "Verification of Vehicle Repair" procedure.
Verification of Vehicle Repair
After a repair, it is essential to verify that the fault has been corrected.
1. Connect scan tool and select "Diagnostic Trouble Codes (DTCs)" mode
2. Using a Scantool, Clear DTC.
3. Operate the vehicle within DTC Detecting Condition in General Information.
4. Are any DTCs present?
YES - Go to the applicable troubleshooting procedure.
NO - System performing to specification at this time.