Motor Driven Power Steering

Description and Operation

Description

The MDPS (Motor Driven Power Steering) system uses an electric motor to assist steering effort, and steering operates independently of engine operation. The MDPS ECU controls motor operation according to information received from each sensor and the CAN (Controller Area Network). This results in more precise and timely control of the steering assist than conventional engine-driven hydraulic systems. The MDPS components (angle sensor, torque sensor, fail-safe relay, etc.) are located inside the steering column. The MDPS assembly, steering column, and MDPS unit must not be disassembled for inspection. Replace them if necessary.

Components and Component Location

Components

1. Steering column 2. Universal joint

3. MDPS motor 4. MDPS ECU

Circuit Diagrams

Schematic Diagrams

Harness Connector

Type	Pin No.	Description
Battery	1	Battery +
	2	Battery -
VSS	1	IGN
	2	-
	3	-
	4	-
	5	-
	6	-
	7	HIGH CAN
	8	LOW CAN

Repair Procedures

Airbag System Repair Procedures

MDPS A/S Work Flow

① Connector and Wiring Inspection

1. Connector and Wiring Inspection. Check each connector and wiring for damage, binding, or improper connection.
   1. Check the wiring on the vehicle side.
      • Check for open/short circuit due to improper connection, damage, or foreign material.

        

   2. Check the wiring on the ECU side (motor 3-phase power).
      • Check for open/short circuit due to improper connection, damage, or foreign material.

        

   3. Check the motor connector.
      • Terminal expansion and damage.

        

   4. Check the motor wiring.

      

② DTC Troubleshooting Items

Item	Trouble Code	Description	Inspection	Service Action
CAN line	C1611	MAY EXCLUDE EMC	1. Check GDS. 2. Check connector tightening. 3. Inspect the ECU CAN connector. 4. Check the MDPS vehicle ground condition.	Check the EMS CAN line
	C1616	CAN BUS OFF		Check whether the chassis line
	C1622	Vehicle speed signal error		Check EMS (Engine Control Module)
Torque Sensor	C1290	Torque sensor signal error	Check after DTC clear. Check connector tightening.	Replace the column and housing if the symptom persists
	C1112	Torque sensor power supply voltage error	Check the torque sensor and ECU connector.	Replace the ECU if the problem persists
ECU	C1604	ECU hardware error	Inspect the ECU connector after clearing the DTC.	Replace the ECU if the problem persists
ECU	C1705	EPS module precharge circuit malfunction	Inspect the ECU connector after clearing the DTC.	Replace the ECU if the problem persists
Motor	C2400	Motor signal error	Check the motor connector after clearing the DTC.	Replace the motor if the problem persists
Motor	C2401	Motor position sensor error	Check the motor connector after clearing the DTC.	Replace the motor if the problem persists
ECU / motor	C2412	Motor current error	Check the motor/ECU connector after clearing the DTC.	Replace the ECU first. Replace the motor if the problem persists
Steering Wheel Angle Sensor	C1259	Steering Wheel Angle Sensor Malfunction	Steering wheel angle reset after DTC clear Check connector tightening.	Replace the column and housing if the symptom persists
Battery	C1102	Low Battery Voltage	Check the battery voltage condition	Battery charging voltage
Coordinated control	C1696	SPAS signal error	SPAS Inspection	Clear the diagnostic trouble code.
	C1697
Coordinated control	C1612	TCU signal error	GTS Inspection	Clear the diagnostic trouble code.
	C1646
Coordinated control	C1628	Cluster signal error	Cluster Inspection	Clear the diagnostic trouble code.
	C1656
Coordinated control	C1692	VSM signal error	VSM Inspection	Clear the diagnostic trouble code.
	C1693
ABS	C1260	Steering Wheel Angle Signal Error	Check after steering wheel angle reset If code C1259 does not appear, check the CAN line.	Angle reset Clear the trouble code.

Noise/Malfunction Repair Procedures

③ Noise/Malfunction Inspection

Symptom	Malfunction Description and Inspection Method	Countermeasure
Noise/Rattle	1. Noise generated near the MDPS column and housing. Remove the surrounding parts and check whether the same noise occurs.	Replace the partial column and housing component Replace the motor if noise occurs
Noise/Rattle	1. Check the steering wheel and surrounding fasteners. Check the DAB, DAB, clock spring, multifunction switch circuit, etc.	Check the noise of the corresponding part Perform a separate inspection.
	2. Check where the C-MDPS is installed. Loosen the column cover mounting bolt and reassemble. (including the through bolt of the lower MDPS mounting)	Check cover installation
	3. Check the universal joint bolt mounting area. Fully remove the universal joint and check whether the noise occurs after reinstallation.	Secure with a new bolt if the universal joint bolt is worn
	4. Check steering column free play while steering with the vehicle stationary. Check the main wiring connected to the MDPS and the rack/interference around the cover/friction.	Maintain clearance between surrounding parts Check free play around the wiring and column and inspect for interference.

④ Service Precautions

Precautions when handling MDPS (Motor Driven Power Steering)

1. 1
   Malfunction caused by internal damage from dropping and impact, and excessive external force on the new partial component. → Be careful not to strike the partial component, and replace any damaged part (due to dropping, etc.) with a new one.
2. 2
   When installing the steering wheel, excessive impact may twist the center point of the torque sensor.
3. 3
   When removing/installing the connector, wiring may be damaged (deformed) by excessive external force.
4. 4
   Be careful when storing and replacing individual components under abnormal temperature and humidity conditions.