DTC C1278, C1956

B3E060201038W09

DTC

C1278, C1956

P/S angle sensor

DETECTION CONDITION

• C1278
- The EHPAS control module detects that the monitor voltage from the P/S angle sensor is more than 4.25 V or less than 0.5 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.
• C1956
- The EHPAS control module detects that the power supply voltage of the P/S angle sensor is more than 5.5 V.
- The EHPAS control module detects that the power supply voltage of the P/S angle sensor is less than 4.5 V.

POSSIBLE CAUSE

• Short to power supply, open circuit, or short to ground in wiring harness between EHPAS control module terminal 3B and P/S angle sensor D
• Short to power supply, open circuit, or short to ground in wiring harness between EHPAS control module terminal 3D and P/S angle sensor terminal B
• Open circuit or short to ground in wiring harness between EHPAS control module terminal 3C and P/S angle sensor terminal C
• Open circuit in wiring harness between EHPAS control module terminal 3A and P/S angle sensor terminal A
• Short circuit in wiring harness between P/S angle sensor terminal B and D
• P/S angle sensor ring has fallen off.
• Power supply voltage of P/S angle sensor is more than the specified value.

Diagnostic procedure

STEP

INSPECTION

ACTION

1
INSPECT POWER SUPPLY VOLTAGE OF P/S ANGLE SENSOR
• Turn the ignition switch to the ON position (Engine off).
• Measure the voltage between P/S angle sensor terminal C and ground.
• Is the voltage 4.5-5.5 V?
Yes
Go to the next step.
No
Repair or replace the wiring harness between EHPAS control module terminal 3C and P/S angle sensor terminal C, then go to the step 7.
2
INSPECT GROUND CIRCUIT OF P/S ANGLE SENSOR FOR OPEN CIRCUIT
• Turn the ignition switch off.
• Disconnect the EHPAS control module and P/S angle sensor connectors.
• Inspect for continuity between EHPAS control module terminal 3A and P/S angle sensor terminal A.
• Is there continuity?
Yes
Go to the next step.
No
Repair or replace the wiring harness between EHPAS control module terminal 3A and P/S angle sensor terminal A, then go to the step 7.
3
INSPECT P/S 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 P/S angle sensor, then go to the step 7.
No
Go to next step.
4
INSPECT P/S 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 P/S angle sensor, then go to the step 7.
No
Go to the next step.
5
INSPECT SENSORS 1 AND 2 OF THE P/S ANGLE SENSOR FOR CONTINUITY
• Turn the ignition switch off.
• Disconnect the EHPAS control module and P/S angle sensor connectors.
• Inspect for continuity between P/S angle sensor terminals B and D.
• Is there continuity?
Yes
Replace the P/S angle sensor, then go to the step 7.
No
Go to the next step.
6
INSPECT PID FOR P/S ANGLE SENSOR RING MALFUNCTION USING WDS OR EQUIVALENT
• Turn the ignition switch off.
• Connect the WDS or equivalent to the DLC-2.
• Select the "STEER_RATE" PID.
• Verify that the WDS display changes correctly according to steering wheel operation.
• Does it change correctly?
Yes
Go to the next step.
No
Replace the P/S angle sensor ring (built into the steering gear valve housing), then go to the next step.
7
VERIFY THAT THE SAME DTC IS NOT PRESENT
• Reconnect all disconnected connectors.
• Clear the DTC from the memory.
• Is the same DTC present?
Yes
• Repeat the inspection from Step 1.
• If the malfunction recurs, replace the electric power steering oil pump.
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 DTC Table.)
No
DTC troubleshooting completed.