DTC C1278 [ELECTRO HYDRAULIC POWER ASSIST STEERING (EHPAS)]

id0602b1801000

DTC

C1278

Steering angle sensor

DETECTION CONDITION

•  The EHPAS control module detects that the monitor voltage from the steering angle sensor is more than 4.9 V or less than 0.8 V

•  The EHPAS control module detects that the two monitor voltages modulate at the same phase a specified amount of phases or more.

•  The EHPAS control module detects that the EHPAS sensor signal dose not change.

POSSIBLE CAUSE

•  Short to power supply, open circuit, or short to ground in wiring harness between EHPAS control module terminal 3B and steering angle sensor B

•  Short to power supply, open circuit, or short to ground in wiring harness between EHPAS control module terminal 3D and steering angle sensor terminal C

•  Open circuit in wiring harness between EHPAS control module terminal 3A and steering angle sensor terminal D (without DSC)

•  Open circuit in wiring harness between DSC HU/CM terminal AH and steering angle sensor terminal D (with DSC)

•  Short circuit in wiring harness between steering angle sensor terminal A and D

•  Steering angle sensor malfunction.

•  Steering angle sensor ring has fallen off.

Diagnostic procedure

STEP	INSPECTION		ACTION
1	INSPECT PID FOR STEERING ANGLE SENSOR MALFUNCTION USING M-MDS • Turn the ignition switch off. • Connect the M-MDS to the DLC-2. • Select the “STEER_RATE” PID. • Verify that the M-MDS display changes correctly according to steering wheel operation. • Does it change correctly?	Yes	Go to the next step.
1		No	Replace the steering angle sensor. (See CLOCK SPRING REMOVAL/INSTALLATION.)
2	INSPECT POWER SUPPLY VOLTAGE OF STEERING ANGLE SENSOR • Turn the ignition switch to the ON position (Engine off). • Measure the voltage between steering angle sensor terminal A and ground. • Is the voltage B+?	Yes	Go to the next step.
2		No	Without DSC • Repair or replace the wiring harness between ignition switch and steering angle sensor terminal A, then go to the step 7. With DSC • Repair or replace the wiring harness between DSC HU/CM terminal AB and steering angle sensor terminal A, then go to the step 7.
3	INSPECT GROUND CIRCUIT OF STEERING ANGLE SENSOR FOR OPEN CIRCUIT • Turn the ignition switch off. • Disconnect the EHPAS control module (without DSC) or DSC HU/CM (with DSC) and steering angle sensor connectors. • Inspect for continuity between EHPAS control module terminal 3A (without DSC) or DSC HU/CM terminal AH (with DSC) and steering angle sensor terminal D. • Is there continuity?	Yes	Go to the next step.
3		No	Repair or replace the wiring harness between EHPAS control module terminal 3A (without DSC) or DSC HU/CM terminal AH (with DSC) and steering angle sensor terminal D, then go to the step 7.
4	INSPECT STEERING ANGLE SENSOR SIGNAL CIRCUIT FOR SHORT TO POWER • Turn ignition key to ON (engine OFF). • Measure the voltage between the EHPAS control module and body ground at the following: ― Sensor 1: EHPAS control module terminal 3B and body ground ― Sensor 2: EHPAS control module terminal 3D and body ground • Is voltage B+?	Yes	Repair or replace the related wiring harnesses between the EHPAS control module and steering angle sensor, then go to the step 7.
4		No	Go to next step.
5	INSPECT STEERING ANGLE SENSOR SIGNAL CIRCUIT FOR SHORT TO GROUND • Turn the ignition switch off. • Inspect continuity between the EHPAS control module and body ground at the following: ― Sensor 1: EHPAS control module terminal 3B and body ground ― Sensor 2: EHPAS control module terminal 3D and body ground • Is there continuity?	Yes	Repair or replace the related wiring harnesses between the EHPAS control module and steering angle sensor, then go to the step 7.
5		No	Go to the next step.
6	INSPECT SENSORS 1 AND 2 OF THE STEERING ANGLE SENSOR FOR CONTINUITY • Turn the ignition switch off. • Disconnect the EHPAS control module and steering angle sensor connectors. • Inspect for continuity between steering angle sensor terminals B and C. • Is there continuity?	Yes	Replace the steering angle sensor, then go to the step 7. (See CLOCK SPRING REMOVAL/INSTALLATION.)
6		No	Go to the next step.
7	VERIFY THAT THE SAME DTC IS NOT PRESENT • Reconnect all disconnected connectors. • Clear the DTC from the memory. (See ON-BOARD DIAGNOSIS [ELECTRO HYDRAULIC POWER ASSIST STEERING (EHPAS)].) • Is the same DTC present?	Yes	• Repeat the inspection from Step 1. • If the malfunction recurs, replace the electric power steering oil pump component. (See ELECTRIC POWER STEERING OIL PUMP COMPONENT REMOVAL/INSTALLATION [ZY, LF, L3, MZ-CD 1.6 (Y6)].)
7		No	Go to the next step.
8	VERIFY THAT NO OTHER DTCS ARE PRESENT • Are any other DTCs output?	Yes	Go to the applicable DTC inspection. (See ON-BOARD DIAGNOSIS [ELECTRO HYDRAULIC POWER ASSIST STEERING (EHPAS)].)
8		No	DTC troubleshooting completed.

DTC	C1278		Steering angle sensor
DETECTION CONDITION		• The EHPAS control module detects that the monitor voltage from the steering angle sensor is more than 4.9 V or less than 0.8 V • The EHPAS control module detects that the two monitor voltages modulate at the same phase a specified amount of phases or more. • The EHPAS control module detects that the EHPAS sensor signal dose not change.
POSSIBLE CAUSE		• Short to power supply, open circuit, or short to ground in wiring harness between EHPAS control module terminal 3B and steering angle sensor B • Short to power supply, open circuit, or short to ground in wiring harness between EHPAS control module terminal 3D and steering angle sensor terminal C • Open circuit in wiring harness between EHPAS control module terminal 3A and steering angle sensor terminal D (without DSC) • Open circuit in wiring harness between DSC HU/CM terminal AH and steering angle sensor terminal D (with DSC) • Short circuit in wiring harness between steering angle sensor terminal A and D • Steering angle sensor malfunction. • Steering angle sensor ring has fallen off.