C1290 Torque sensor main signal fail

COMPONENT LOCATION

GENERAL DESCRIPTION

EPS CM receives torque and rotation speed of steering wheel from torque sensor.

The EPS CM uses a torque sensor as it’s main input for determining the amount of steering assists. The input and output shafts are separated by a torsion bar, where the torque sensor is located. The sensor consists of a two detecting plates. Detecting plate 1 is fixed to the output shaft, detecting plate 2 is fixed to the input shaft. As torque is applied to the steering column shaft the alignment of the teeth between detecting plate 1 and 2 changes. The EPS CM recognizes this change.

DTC DESCRIPTION

The EPS CM sets this code if torque sensor can’t calculate torque and rotation speed normally due to open or short in torque sensor circuit or discordance between 2 sensing element signal.

The EPS CM turns on warning lamp and stops assist control.

DTC DETECTING CONDITION

Item

Detecting Condition

Possible cause

DTC Strategy

Check signal & Compare 2 sensing element signal

Poor connection in torque sensor

Improper installation of torque sensor

Enable conditions

IG ON

Threshold value

Signal error or discordance between 2 sensing element signal

Fail Safe

EPS warning lamp “ON”, EPS control is inhibited

Restoration conditions

Normal condition after IG on → off

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.

4.	Monitor the “Torque Sensor” parameters on the Scantool.

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

	▶ Fault is intermittent and caused either by poor contact in Torque sensor or wiring harness, or it has been repaired and EPS CM memory is not cleared yet. Repair or replace as necessary.
	▶ Go to “Component Inspection” procedure

TERMINAL AND CONNECTOR INSPECTION

1.	Many malfunctions in the electrical system are caused by poor harness and terminal s. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.

2.	Thoroughly check all connectors (and connections) for looseness, bending, corrosion, contamination, deterioration, and/or damage.

Has a problem been found ?

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

COMPONENT INSPECTION

1.	Ignition “OFF”.

2.	Ignition “ON” & Engine “OFF”.

3.	Connect scantool and select “Diagnostic Trouble Codes(DTCs)” mode

4.	Using a scantool, Clear DTC.

5.	Operate the vehicle within DTC Detecting Condition in General Information. (turn right and left at least 1 time)

6.	Select “Diagnostic Trouble Codes(DTCs)” mode again.

Are any DTCs present ?

	▶ Substitute with a known-good steering column & EPS unit assembly check for proper operation. If problem is corrected, replace steering column & EPS unit assembly
	▶ Fault is intermittent caused by faulty EPS CM or was repaired and EPS CM memory was not cleared.

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