DTC C1278, C1956

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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. (See STEERING GEAR AND LINKAGE DISASSEMBLY.) (See STEERING GEAR AND LINKAGE ASSEMBLY.)
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. (See STEERING GEAR AND LINKAGE DISASSEMBLY.) (See STEERING GEAR AND LINKAGE ASSEMBLY.)
7 | VERIFY THAT THE SAME DTC IS NOT PRESENT • Reconnect all disconnected connectors. • Clear the DTC from the memory. (See Clearing DTCs Procedure.) • Is the same DTC present? | Yes | • Repeat the inspection from Step 1. • If the malfunction recurs, replace the electric power steering oil pump. (See ELECTRIC POWER STEERING OIL PUMP (LF) REMOVAL/INSTALLATION.)
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.