C1260 Steering Angle Sensor Circuit-Signal - Automotive Repair Guides & Equipment

COMPONENT 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 the signal is used to input signal for anti-roll control.

DTC DESCRIPTION

The HECU monitors signals of the steering angle sensor and if the measured angle from the sensor differs with the calculated angle, the ECU detects the failure and sets this code.

DTC DETECTING CONDITION

Item

Detecting Condition

Possible cause

DTC Strategy

Signal Monitoring

Faulty steering angle sensor

Incorrect installation of the sensor

Enable Conditions

When the difference between calculated angle rate and measured angle rate of the SAS sensor is lager than predetermined value, failure is detected

During straight driving, if the steering wheel angle is larger than 55 degree ECU detects the failure.

When the steering wheel angle is larger than ±780 degrees, ECU detects the failure.

When the difference between estimated angle and measured angle of the SAS sensor is larger than 50 deg/s, failure is detected.

In case that diagnostic signal fault of SAS was happened.

Fail Safe

Inhibit the ESP control and allow the ABS/EBD control.

The ESP warning lamp is activated.

DIAGNOSTIC CIRCUIT DIAGRAM

SIGNAL WAVEFORM & DATA

Fig 1) Normal waveform at turning the steering wheel

MONITOR SCANTOOL DATA

1.	Connect scantool to Data Link Connector(DLC).

2.	Ignition “ON” & Engine “ON”.

3.	Turn the steering wheel to the left or right.

Monitor the “STEERING ANGLE SNSR” parameters on the Scantool.

If the parameters are changed according to wheel position during steering the wheel, it is normal condition.

Fig 1) Normal data at turning the steering wheel into the left

Whenever steering wheel is turned, is the steering sensor’s scantool data changed?

	▶ 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. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary
	▶ Go to “Terminal and Connector 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.

Has a problem been found?

	▶ Repair as necessary .
	▶ Go to “Component Inspection” procedure.

COMPONENT INSPECTION

■ Steering Angel Sensor Check

1.	Ignition “ON” & Engine “ON”.

2.	Turn the steering wheel to the left or right.

Measure waveform between signal terminal of the steering angle sensor harness connector and chassis ground with osciloscope.

Specification : Check if the voltage of signal waveform is normal.

(HIGH : 2.9±0.1V ~ 4.4±0.1V, LOW : 1.2±0.1V ~ 2.1±0.1V)

Check if normal signal waveform comes up while turning the steering wheel.

Is the measured waveform normal?

	▶ Fault is intermittent caused by poor connection in steering sensor harness and/or HECU’s connector.
	▶ Check for improper installation of steering angle sensor. Repair as necessary . If sensor mounting state is normal, Substitute with a known-good steering angle sensor and check for proper operation. If problem is corrected, replace steering angle sensor

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