C1103 Ignition Voltage Fault - Automotive Repair Guides & Equipment

COMPONENT LOCATION

GENERAL DESCRIPTION

EPS CM receives vehicle speed and engine RPM signal from EMS(Engine Management System) via CAN line and controls motor current accurately according to driver’s steering intention. EPS CM monitors that operating voltage supplied as IG S/W is too high or too low on “power supply terminal”. If excessive high voltage or low voltage is detected, EPS CM stops current supply to solenoid to prevent unexpected operation or damage.

DTC DESCRIPTION

EPS is designed to operate only at engine “ON” because it’s current attrition rate is high. It decides whether engine operates or not from vehicle speed and engine RPM. EPS CM sets this code and turns on warning lamp if IG S/W turns off when engine is operating.

DTC DETECTING CONDITION

Item

Detecting Condition

Possible cause

DTC Strategy

Voltage Monitoring

Faulty ground circuit

Poor connection in ground circuit

Open in IG circuit

Enable conditions

Engine RPM > 500 & Vehicle speed > 2.7Km/h

Threshold value

IG S/W Off

Fail Safe

EPS warning lamp “ON”

(Back up function maintained for 310sec)

Restoration conditions

IG On

SPECIFICATION

Bat. Voltage	IG Key ON	ENG. ON
Bat. Voltage	Approx. 11.8 [V]~12.5 [V]	Approx. 12.5 [V] ~ 14.5 [V]

DIAGNOSTIC CIRCUIT DIAGRAM

MONITOR SCANTOOL DATA

1.	Connect scantool to Data Link Connector(DLC).

2.	Start engine and turn the headlight on.

3.	Monitor the “BATTERY VOLTAGE” parameter on the scantool.

Maintaining ENG. RPM at 2,500RPM(idle) over 2 minutes.

Battery Voltage

Is parameter 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. Thoroughly check all connectors (and connections) for looseness, bending, corrosion, contamination, deterioration, and/or damage. ▶ Repair or replace as necessary
	▶ Go to “W/Harness Inspection” procedure.

ERMINAL AND CONNECTOR INSPECTION

1.	Many malfunctions in the electrical system are caused by poor harness and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.

2.	Thoroughly check all connectors (and connections) for looseness, bending, corrosion, contamination, deterioration, and/or damage.

Has a problem been found?

	▶ Repair as necessary
	▶ Go to “Power Circuit Inspection” procedure.

POWER CIRCUIT INSPECTION

■ Open or Short Check

1.	Ignition “OFF”

2.	Disconnect EPS CM connector.

3.	Ignition “ON” & Engine “OFF”.

Measure voltage between ON/START INPUT terminal of EPS CM harness connector and chassis ground.

Battery Voltage

Is the measured voltage within specifications?

	▶ Go to “Ground Circuit Inspection” procedure.
	▶ Check for open or blown fuse referring to “Circuit Diagram”. Repair open or short in power circuit between battery and EPS CM harness connector and then go to “Verification of vehicle Repair” procedure.

GROUND CIRCUIT INSPECTION

■ Open or Short Check

1.	Ignition “OFF”.

2.	Disconnect EPS CM connector.

Measure resistance between ground terminal of EPS CM harness connector and chassis ground.

Approx. 1.0 Ω

Is the measured resistance within specifications?

	▶ Substitute with a known-good steering column & EPS unit assembly and check for proper operation. If the problem is corrected, replace steering column & EPS unit assembly .
	▶ Check for open or contact resistance in ground harness. Repair as necessary

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