C1603 Derating (EPS Thermal Protection) - Automotive Repair Guides & Equipment

COMPONENT LOCATION

GENERAL DESCRIPTION

EPS uses an electric motor to provide directional contol to the driver. An electric mortor consumes much current during operating. It can be overheat under excessive use, at that time EPS CM restricts motor current for protecting EPS from unexpected problem.

DTC DESCRIPTION

EPS CM sets this code If temperature of EPS CM is higher than 85°C (185°F) due to excessive use.

EPS CM restricts assist steering function to decrease motor current.

EPS CM inhibits assist steering if temperature of EPS CM is higher than 120°C (248°F).

DTC DETECTING CONDITION

Item

Detecting Condition

Possible cause

DTC Strategy

Check motor temperature

Continous Steering operation

Enable conditions

IG ON & Engine ON

Threshold value

Temperature of EPS CM > 85°C (185°F).

Fail Safe

The power of EPS is restricted.

Restoration conditions

Temperature of EPS CM < 85°C (185°F).

MONITOR SCANTOOL DATA

1.	Connect scantool to Data Link Connector(DLC)

2.	Ignition “ON” & Engine “ON”.

Monitor the “MOTOR TEMPERATURE” parameters on the Scantool.

Less than 85°C (185°F)

Fig.1) Normal data (IG ON & ENG ON)

Is the measured “Motor Temperature” within specifications?

	▶ Fault is intermittent and caused either by poor contact in connectors or wiring harness, or it has been repaired and EPS CM memory is not cleared yet.
	▶ Wait till the EPS motor cool down sufficiently. 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.	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
	▶ The DTC code can be set by excessive EPS control in normal system status. Go to “Verification of Vehicle Repair” procedure.

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